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AP/HP Pôle 5

- Centre de Génétique Médicale Jean Frézal -

Réponses affichées : 667

RAB23 mutation in a large family from Comoros Islands with Carpenter syndrome

ALESSANDRI JL, DAGONEAU N, LAVILLE JM, BARUTEAU J, HEBERT JC, CORMIER-DAIRE V

2010 - Am J Med Genet A 152A(4):982-6

We report here on a RAB23 mutation (c.86dupA) present in the homozygote state in four relatives of Comorian origin with Carpenter syndrome. All children presented with acrocephaly and polysyndactyly. However, intrafamilial variability was observed with variable severity of craniosynostosis ranging from cloverleaf skull to predominant involvement of the metopic ridge. All children also presented with a combination of brachydactyly with agenesis of the middle phalanges, syndactyly, broad thumbs, and postaxial polydactyly (2/4) in the hands, and preaxial polydactyly (3) and syndactyly (4) in the toes. Mental development was normal in all four children but the eldest one presented with impaired motor development as a result of orthopedic complications. Brain imaging showed hydrocephalus in 2/4 and additional features included genu valgum (2/4), abnormal genitalia (3/4), corneal anomaly (2/4), umbilical hernia (1/4), severe cyphoscoliosis (1), patent ductus arteriosus (1/4), and accessory spleen (1). In contrast to previous reports, growth was below average except for one patient and the eldest one became moderately overweight with time. We conclude from the report of this large unique family with four affected children that Carpenter syndrome is a genetically homogenous but a clinically variable condition.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

New ocular phenotype associated with a mutation in the PAX2 gene

BEBY F, ROCHE O, COCHAT P, RANCHIN B, KOHLER R, BONIFAS C, CORDIER MP, ATTIE-BITACH T, BURILLON C, DENIS P

2010 - Eye (Lond) 24(7):1293-4

Unité(s) : Centre de Génétique Médicale Jean Frézal, Ophtalmologie, U781

In vitro readthrough of termination codons by gentamycin in the Stuve-Wiedemann Syndrome

BELLAIS S, LE GOFF C, DAGONEAU N, MUNNICH A, CORMIER-DAIRE V

2010 - Eur J Hum Genet 18(1):130-32

The Stuve-Wiedemann Syndrome (SWS) is a frequently lethal chondrodysplasia caused by null mutations in the leukemia inhibitory factor receptor gene (LIFR) responsible for an impaired activation of the JAK-STAT pathway after LIF stimulation. Most LIFR mutations are nonsense mutations, thus prompting us to investigate the impact of aminoglycosides on the readthrough of premature termination codons (PTCs). Culturing skin fibroblasts from three SWS patients and controls for 48 h in the presence of gentamycin (200-500 mug/ml) partially restored the JAK-STAT3 pathway when stimulated by LIF. Consistently, quantitative RT-PCR analysis showed that gentamycin stabilized LIFR mRNAs carrying UGA premature termination codons. We conclude that high gentamycin concentrations can partially restore functional LIFR protein synthesis in vitro, prompting us to investigate PTC readthrough using less toxic and more efficient drugs in this presently untreatable lethal condition.European Journal of Human Genetics advance online publication, 15 July 2009; doi:10.1038/ejhg.2009.122.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Hereditary nephrotic syndrome: a systematic approach for genetic testing and a review of associated podocyte gene mutations

BENOIT G, MACHUCA E, ANTIGNAC C

2010 - Pediatr Nephrol 25(9):1621-32

Several genes have been implicated in genetic forms of nephrotic syndrome occurring in children. It is now known that the phenotypes associated with mutations in these genes display significant variability, rendering genetic testing and counselling a more complex task. This review will focus on the recent clinical findings associated with those genes known to be involved in isolated steroid-resistant nephrotic syndrome in children and, thereby, propose an approach for appropriate mutational screening. The recurrence of proteinuria after transplantation in patients with hereditary forms of nephrotic syndrome will also be discussed.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U983

Analysis of recessive CD2AP and ACTN4 mutations in steroid-resistant nephrotic syndrome

BENOIT G, MACHUCA E, NEVO F, GRIBOUVAL O, LEPAGE D, ANTIGNAC C

2010 - Pediatr Nephrol 25(3):445-51

Mutations in podocyte genes have been identified in patients with steroid-resistant nephrotic syndrome (SRNS). Point mutations in the ACTN4 gene cause an autosomal dominant form of human focal segmental glomerular sclerosis (FSGS); however, reports of CD2AP mutations remain scarce. Based on the phenotype of Actn4 and Cd2ap null mice, we aimed to define the role of recessive CD2AP and ACTN4 mutations in a cohort of children with SRNS for which NPHS1, NPHS2, and PLCE1 mutations had been previously excluded. CD2AP and ACTN4 mutational analysis was performed in 42 children from 35 unrelated families. The median age of disease onset was 20 (range 0-102) months. Sixteen patients reached end-stage kidney disease at a median age of 84 (range 4-161) months. Renal histology showed FSGS lesions and minimal glomerular changes in 49% and 20% of patients, respectively. Microsatellite marker analysis excluded linkage to the CD2AP locus in 26 families and to the ACTN4 locus in 31 families. No disease-causing mutations were identified in the remaining families. Recessive CD2AP and ACTN4 mutations are rare in children with SRNS. The absence of mutations in this study suggests that there are other genetic causes of SRNS that still need to be identified.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U983

Pediatric Mastocytosis Is a Clonal Disease Associated with D(816)V and Other Activating c-KIT Mutations

BODEMER C, HERMINE O, PALMERINI F, YANG Y, GRANDPEIX-GUYODO C, LEVENTHAL PS, HADJ-RABIA S, NASCA L, GEORGIN-LAVIALLE S, COHEN-AKENINE A, LAUNAY JM, BARETE S, FEGER F, AROCK M, CATTEAU B, SANS B, STALDER JF, SKOWRON F, THOMAS L, LORETTE G, PLANTIN P, BORDIGONI P, LORTHOLARY O, PROST Y, MOUSSY A, SOBOL H, DUBREUIL P

2010 - J Invest Dermatol 130(3):804-15

Adult mastocytosis is an incurable clonal disease associated with c-KIT mutations, mostly in exon 17 (D(816)V). In contrast, pediatric mastocytosis often spontaneously regresses and is considered a reactive disease. Previous studies on childhood mastocytosis assessed only a few patients and focused primarily on codon 816 mutations, with various results. In this study, we analyzed the entire c-KIT sequence from cutaneous biopsies of 50 children with mastocytosis (ages 0-16 years). A mutation of codon 816 (exon 17) was found in 42% of cases, and mutations outside exon 17 were observed in 44%. Unexpectedly, half of the mutations were located in the fifth Ig loop of c-KIT's extracellular domain, which is encoded by exons 8 and 9. All mutations identified in this study were somatic and caused a constitutive activation of c-KIT. There was no clear phenotype-genotype correlation, no clear relationship between the mutations and familial versus spontaneous disease, and no significant change in the relative expression of the c-KIT GNNK+ and GNNK isoforms. These findings strongly support the idea that, although pediatric mastocytosis can spontaneously regress, it is a clonal disease most commonly associated with activating mutations in c-KIT.JID JOURNAL CLUB ARTICLE: For questions and answers about this article, please go to http://www.nature.com/jid/journalclub.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Dermatologie, Maladies Infectieuses, UMR 8147

Elastase 2 is expressed in human and mouse epidermis and impairs skin barrier function in Netherton syndrome through filaggrin and lipid misprocessing

BONNART C, DERAISON C, LACROIX M, UCHIDA Y, BESSON C, ROBIN A, BRIOT A, GONTHIER M, LAMANT L, DUBUS P, MONSARRAT B, HOVNANIAN A

2010 - J Clin Invest 120(3):871-82

The human epidermis serves 2 crucial barrier functions: it protects against water loss and prevents penetration of infectious agents and allergens. The physiology of the epidermis is maintained by a balance of protease and antiprotease activities, as illustrated by the rare genetic skin disease Netherton syndrome (NS), in which impaired inhibition of serine proteases causes severe skin erythema and scaling. Here, utilizing mass spectrometry, we have identified elastase 2 (ELA2), which we believe to be a new epidermal protease that is specifically expressed in the most differentiated layer of living human and mouse epidermis. ELA2 localized to keratohyalin granules, where it was found to directly participate in (pro-)filaggrin processing. Consistent with the observation that ELA2 was hyperactive in skin from NS patients, transgenic mice overexpressing ELA2 in the granular layer of the epidermis displayed abnormal (pro-)filaggrin processing and impaired lipid lamellae structure, which are both observed in NS patients. These anomalies led to dehydration, implicating ELA2 in the skin barrier defect seen in NS patients. Thus, our work identifies ELA2 as a major new epidermal protease involved in essential pathways for skin barrier function. These results highlight the importance of the control of epidermal protease activity in skin homeostasis and designate ELA2 as a major protease driving the pathogenesis of NS.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Microdeletion at chromosome 4q21 defines a new emerging syndrome with marked growth restriction, mental retardation and absent or severely delayed speech

BONNET C, ANDRIEUX J, BERI-DEXHEIMER M, LEHEUP B, BOUTE O, MANOUVRIER S, DELOBEL B, COPIN H, RECEVEUR A, MATHIEU M, THIRIEZ G, LE CAIGNEC C, DAVID A, DE BLOIS MC, MALAN V, PHILIPPE A, CORMIER-DAIRE V, COLLEAUX L, FLORI E, DOLLFUS H, PELLETIER V, THAUVIN-ROBINET C, MASUREL-PAULET A, FAIVRE L, TARDIEU M, BAHI-BUISSON N, CALLIER P, MUGNERET F, EDERY P, JONVEAUX P, SANLAVILLE D

2010 - J Med Genet 47(6):377-84

Background Genome-wide screening of large patient cohorts with mental retardation using microarray-based comparative genomic hybridisation (array-CGH) has recently led to identification several novel microdeletion and microduplication syndromes. Methods Owing to the national array-CGH network funded by the French Ministry of Health, shared information about patients with rare disease helped to define critical intervals and evaluate their gene content, and finally determine the phenotypic consequences of genomic array findings. Results In this study, nine unrelated patients with overlapping de novo interstitial microdeletions involving 4q21 are reported. Several major features are common to all patients, including neonatal muscular hypotonia, severe psychomotor retardation, marked progressive growth restriction, distinctive facial features and absent or severely delayed speech. The boundaries and the sizes of the nine deletions are different, but an overlapping region of 1.37 Mb is defined; this region contains five RefSeq genes: PRKG2, RASGEF1B, HNRNPD, HNRPDL and ENOPH1. Discussion Adding new individuals with similar clinical features and 4q21 deletion allowed us to reduce the critical genomic region encompassing two genes, PRKG2 and RASGEF1B. PRKG2 encodes cGMP-dependent protein kinase type II, which is expressed in brain and in cartilage. Information from genetically modified animal models is pertinent to the clinical phenotype. RASGEF1B is a guanine nucleotide exchange factor for Ras family proteins, and several members have been reported as key regulators of actin and microtubule dynamics during both dendrite and spine structural plasticity. Conclusion Clinical and molecular delineation of 4q21 deletion supports a novel microdeletion syndrome and suggests a major contribution of PRKG2 and RASGEF1B haploinsufficiency to the core phenotype.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Histo-Embryologie - Cytogénétique, Neurologie, U781

Mutational analysis of the PLCE1 gene in steroid resistant nephrotic syndrome

BOYER O, BENOIT G, GRIBOUVAL O, NEVO F, PAWTOWSKI A, BILGE I, BIRCAN Z, DESCHENES G, GUAY-WOODFORD LM, HALL M, MACHER MA, SOULAMI K, STEFANIDIS CJ, WEISS R, LOIRAT C, GUBLER MC, ANTIGNAC C

2010 - J Med Genet 47(7):445-52

Background Mutations in the PLCE1 gene encoding phospholipase C epsilon 1 (PLCepsilon1) have been recently described in patients with early onset nephrotic syndrome (NS) and diffuse mesangial sclerosis (DMS). In addition, two cases of PLCE1 mutations associated with focal segmental glomerulosclerosis (FSGS) and later NS onset have been reported. Method In order to better assess the spectrum of phenotypes associated with PLCE1 mutations, mutational analysis was performed in a worldwide cohort of 139 patients (95 familial cases belonging to 68 families and 44 sporadic cases) with steroid resistant NS presenting at a median age of 23.0 months (range 0-373). Results Homozygous or compound heterozygous mutations were identified in 33% (8/24) of DMS cases. PLCE1 mutations were found in 8% (6/78) of FSGS cases without NPHS2 mutations. Nine were novel mutations. No clear genotype-phenotype correlation was observed, with either truncating or missense mutations detected in both DMS and FSGS, and leading to a similar renal evolution. Surprisingly, three unaffected and unrelated individuals were also found to carry the homozygous mutations identified in their respective families. Conclusion PLCE1 is a major gene of DMS and is mutated in a non-negligible proportion of FSGS cases without NPHS2 mutations. Although additional variants in 19 candidate genes (16 other PLC genes, BRAF,IQGAP1 and NPHS1) were not identified, it is speculated that other modifier genes or environmental factors may play a role in the renal phenotype variability observed in individuals bearing PLCE1 mutations. This observation needs to be considered in the genetic counselling offered to patients.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Neurochirurgie Pédiatrique, U983

Single-sperm analysis for recurrence risk assessment of spinal muscular atrophy

BURLET P, GIGAREL N, MAGEN M, DRUNAT S, BENACHI A, HESTERS L, MUNNICH A, BONNEFONT JP, STEFFANN J

2010 - Eur J Hum Genet 18(4):505-08

With the detection of a homozygous deletion of the survival motor neuron 1 gene (SMN1), prenatal and preimplantation genetic diagnosis (PGD) for spinal muscular atrophy has become feasible and widely applied. The finding of a de novo rearrangement, resulting in the loss of the SMN1 gene, reduces the recurrence risk from 25% to a lower percentage, the residual risk arising from recurrent de novo mutation or germline mosaicism. In a couple referred to our PGD center because their first child was affected with SMA, the male partner was shown to carry two SMN1 copies. An analysis of the SMN1 gene and two flanking markers was performed on 12 single spermatozoa, to determine whether the father carried a CIS duplication of the SMN1 gene on one chromosome and was a carrier, or if the deletion has occurred de novo. We showed that all spermatozoa that were carriers of the 'at-risk haplotype' were deleted for the SMN1 gene, confirming the carrier status of the father. We provide an original application of single germ cell studies to recessive disorders using coamplification of the gene and its linked markers. This efficient and easy procedure might be useful to elucidate complex genetic situations when samples from other family members are not available.European Journal of Human Genetics advance online publication, 11 November 2009; doi:10.1038/ejhg.2009.198.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781, Obstétrique

Strong medicine for French research

BUTLER D, MUNNICH A

2010 - Nature 466(7302):20

Unité(s) : Centre de Génétique Médicale Jean Frézal

Late-Onset Central Hypoventilation Presenting as Extubation Failure

COHEN-CYMBERKNOH M, SHOSEYOV D, GOLDBERG S, GROSS E, AMIEL J, KEREM E

2010 - Isr. Med. Assoc. J. 12(4):249-250

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

[Malformation syndromes associated with childhood cancer: An update.]

DE PONTUAL L, LYONNET S, AMIEL J

2010 - Arch Pediatr 17(8):1220-1227

Biology, genetics and environment of childhood solid tumours set them apart from adult solid tumours. The nature of the progenitor cells from which these tumours arise, and their immature tissue environment, allows childhood solid tumours to develop with fewer defects in cell regulatory processes. Constitutional molecular defects are known to play a role in childhood solid tumours, as shown by the increased incidence of embryonic cancers in children carrying malformations associated with childhood cancer. These rare diagnoses are commonly missed. In this article, we reviewed the spectrum of these tumour predisposition syndromes.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Search for the best indicators for the presence of a VPS13B gene mutation and confirmation of diagnostic criteria in a series of 34 patients genotyped for suspected Cohen syndrome

EL CHEHADEH S, ARAL B, GIGOT N, THAUVIN-ROBINET C, DONZEL A, DELRUE MA, LACOMBE D, DAVID A, BURGLEN L, PHILIP N, MONCLA A, CORMIER-DAIRE V, RIO M, EDERY P, VERLOES A, BONNEAU D, AFENJAR A, JACQUETTE A, HERON D, SARDA P, PINSON L, DORAY B, VIGNERON J, LEHEUP B, FRANCES-GUIDET AM, DIENNE G, HOLDER M, MASUREL-PAULET A, HUET F, TEYSSIER JR, FAIVRE L

2010 - J Med Genet 47(8):549-53

Background Cohen syndrome is a rare autosomal recessive inherited disorder that results from mutations of the VPS13B gene. Clinical features consist of a combination of mental retardation, facial dysmorphism, postnatal microcephaly, truncal obesity, slender extremities, joint hyperextensibility, myopia, progressive chorioretinal dystrophy, and intermittent neutropenia. Patients and methods The aim of the study was to determine which of the above clinical features were the best indicators for the presence of VPS13B gene mutations in a series of 34 patients with suspected Cohen syndrome referred for molecular analysis of VPS13B. Results 14 VPS13B gene mutations were identified in 12 patients, and no mutation was found in 22 patients. The presence of chorioretinal dystrophy (92% vs 32%, p=0.0023), intermittent neutropenia (92% vs 5%, p<0.001), and postnatal microcephaly (100% vs 48%, p=0.0045) was significantly higher in the group of patients with a VPS13B gene mutation compared to the group of patients without a mutation. All patients with VPS13B mutations had chorioretinal dystrophy and/or intermittent neutropenia. The Kolehmainen diagnostic criteria provided 100% sensibility and 77% specificity when applied to this series. Conclusion From this study and a review of more than 160 genotyped cases from the literature, it is concluded that, given the large size of the gene, VPS13B screening is not indicated in the absence of chorioretinal dystrophy or neutropenia in patients aged over 5 years. The follow-up of young patients could be a satisfactory alternative unless there are some reproductive issues.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Epileptic phenotypes in children with respiratory chain disorders

EL SABBAGH S, LEBRE AS, BAHI-BUISSON N, DELONLAY P, SOUFFLET C, BODDAERT N, RIO M, ROTIG A, DULAC O, MUNNICH A, DESGUERRE I

2010 - Epilepsia 51(7):1225-35

Summary Purpose: Epilepsy is a commonly reported but rarely described clinical hallmark of mitochondrial respiratory chain defects (RCDs) with encephalopathy. Methods: From 1990-2006 we collected data about 56 children with RCD (single, n = 24 or multiple, n = 20 mitochondrial complex deficiencies; mtDNA mutation, n = 11; mtDNA depletion n = 10 of 21; and nuclear gene mutation n = 11). Epileptic features were reviewed retrospectively. Results: First seizures were frequently (47 patients, 82.5%) preceded by failure to thrive, psychomotor delay, ataxia, or multisystemic dysfunction. Sixty percent of the patients had several seizure types. Six age-related epilepsy phenotypes could be identified: status epilepticus complicating neonatal multivisceral deficiency (2 patients), neonatal myoclonic encephalopathy (3 patients), infantile spasms (8 patients), refractory or recurrent status epilepticus (21 patients), epilepsia partialis continua (4 patients), and myoclonic epilepsy (18 patients). Except for infantile spasms, epilepsy was difficult to control in most patients (95%). Valproate was administered to 25 patients, one of whom developed acute liver failure 6 days later. Twenty-two patients (45%) died, half of them within 9 months from the onset of epilepsy. Discussion: In RCD, epilepsy is not only difficult to control but its occurrence often indicates a severe turn in the course of the disease. For one-third of the patients, classical biochemical measures failed to reveal any abnormality and RCD could be detected in the liver only.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Explorations Fonctionnelles, Métabolisme, Neurologie, Radiologie Pédiatrique, U663, U781

Differential contributions of rare and common, coding and noncoding Ret mutations to multifactorial Hirschsprung disease liability

EMISON ES, GARCIA-BARCELO M, GRICE EA, LANTIERI F, AMIEL J, BURZYNSKI G, FERNANDEZ RM, HAO L, KASHUK C, WEST K, MIAO X, TAM PK, GRISERI P, CECCHERINI I, PELET A, JANNOT AS, DE PONTUAL L, HENRION-CAUDE A, LYONNET S, VERHEIJ JB, HOFSTRA RM, ANTINOLO G, BORREGO S, MCCALLION AS, CHAKRAVARTI A

2010 - Am J Hum Genet 87(1):60-74

The major gene for Hirschsprung disease (HSCR) encodes the receptor tyrosine kinase RET. In a study of 690 European- and 192 Chinese-descent probands and their parents or controls, we demonstrate the ubiquity of a >4-fold susceptibility from a C-->T allele (rs2435357: p = 3.9 x 10(-43) in European ancestry; p = 1.1 x 10(-21) in Chinese samples) that probably arose once within the intronic RET enhancer MCS+9.7. With in vitro assays, we now show that the T variant disrupts a SOX10 binding site within MCS+9.7 that compromises RET transactivation. The T allele, with a control frequency of 20%-30%/47% and case frequency of 54%-62%/88% in European/Chinese-ancestry individuals, is involved in all forms of HSCR. It is marginally associated with proband gender (p = 0.13) and significantly so with length of aganglionosis (p = 7.6 x 10(-5)) and familiality (p = 6.2 x 10(-4)). The enhancer variant is more frequent in the common forms of male, short-segment, and simplex families whereas multiple, rare, coding mutations are the norm in the less common and more severe forms of female, long-segment, and multiplex families. The T variant also increases penetrance in patients with rare RET coding mutations. Thus, both rare and common mutations, individually and together, make contributions to the risk of HSCR. The distribution of RET variants in diverse HSCR patients suggests a "cellular-recessive" genetic model where both RET alleles' function is compromised. The RET allelic series, and its genotype-phenotype correlations, shows that success in variant identification in complex disorders may strongly depend on which patients are studied.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Compared effects of missense mutations in Very-Long-Chain Acyl-CoA Dehydrogenase deficiency: Combined analysis by structural, functional and pharmacological approaches

GOBIN-LIMBALLE S, MCANDREW RP, DJOUADI F, KIM JJ, BASTIN J

2010 - Biochim Biophys Acta 1802(5):478-484

Very-Long-Chain Acyl-CoA Dehydrogenase deficiency (VLCADD) is an autosomal recessive disorder considered as one of the more common ss-oxidation defects, possibly associated with neonatal cardiomyopathy, infantile hepatic coma, or adult-onset myopathy. Numerous gene missense mutations have been described in these VLCADD phenotypes, but only few of them have been structurally and functionally analyzed, and the molecular basis of disease variability is still poorly understood. To address this question, we first analyzed fourteen disease-causing amino acid changes using the recently described crystal structure of VLCAD. The predicted effects varied from the replacement of amino acid residues lining the substrate binding cavity, involved in holoenzyme-FAD interactions or in enzyme dimerisation, predicted to have severe functional consequences, up to amino acid substitutions outside key enzyme domains or lying on near enzyme surface, with predicted milder consequences. These data were combined with functional analysis of residual fatty acid oxidation (FAO) and VLCAD protein levels in patient cells harboring these mutations, before and after pharmacological stimulation by bezafibrate. Mutations identified as detrimental to the protein structure in the 3-D model were generally associated to profound FAO and VLCAD protein deficiencies in the patient cells, however, some mutations affecting FAD binding or monomer-monomer interactions allowed a partial response to bezafibrate. On the other hand, bezafibrate restored near-normal FAO rates in some mutations predicted to have milder consequences on enzyme structure. Overall, combination of structural, biochemical, and pharmacological analysis allowed assessment of the relative severity of individual mutations, with possible applications for disease management and therapeutic approach.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Renin-angiotensin system in kidney development: renal tubular dysgenesis

GUBLER MC, ANTIGNAC C

2010 - Kidney Int 77(5):400-6

Autosomal recessive renal tubular dysgenesis (RTD) is a severe disorder of renal tubular development characterized by early onset and persistent fetal anuria leading to oligohydramnios and the Potter sequence. At birth, blood pressure is dramatically low and perinatal death occurs in most cases. Skull ossification defects are frequently associated with RTD. The disease is genetically heterogeneous and linked to mutations in the genes encoding any of the components of the renin-angiotensin system (RAS). An intense stimulation of renin production is noted in the kidneys of patients with mutations in the genes encoding angiotensinogen, angiotensin-converting enzyme, or AT1 receptor, whereas absence or increased renin production is associated with REN defects depending on the type of mutation. The severity of the disease underlines the importance of a functional RAS in the maintenance of blood pressure and renal blood flow during fetal life. The absence or poor development of proximal tubules, as well as renal vascular changes, may be attributable to renal hypoperfusion rather than to a morphogenic property of the RAS. The less severe phenotype in mice devoid of RAS may be linked to differences between mice and humans in the time of nephrogenesis and maturation of the RAS. The identification of the disease on the basis of precise clinical and histological analyses and the characterization of the genetic defects allow genetic counseling and early prenatal diagnosis.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Néphrologie Pédiatrique, U983

Spectrum of HNF1B mutations in a large cohort of patients who harbor renal diseases

HEIDET L, DECRAMER S, PAWTOWSKI A, MORINIERE V, BANDIN F, KNEBELMANN B, LEBRE AS, FAGUER S, GUIGONIS V, ANTIGNAC C, SALOMON R

2010 - Clin J Am Soc Nephrol 5(6):1079-90

BACKGROUND AND OBJECTIVES: Hepatocyte nuclear factor 1beta (HNF1beta) is a transcription factor that is critical for the development of kidney and pancreas. In humans, mutations in HNF1B lead to congenital anomalies of the kidney and urinary tract, pancreas atrophy, and maturity-onset diabetes of the young type 5 and genital malformations. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We report HNF1B screening in a cohort of 377 unrelated cases with various kidney phenotypes (hyperechogenic kidneys with size not more than +3 SD, multicystic kidney disease, renal agenesis, renal hypoplasia, cystic dysplasia, or hyperuricemic tubulointerstitial nephropathy not associated with UMOD mutation). RESULTS: We found a heterozygous mutation in 75 (19.9%) index cases, consisting of a deletion of the whole gene in 42, deletion of one exon in one, and small mutations in 32. Eighteen mutations were novel. De novo mutations accounted for 66% of deletions and 40% of small mutations. In patients who carried HNF1B mutation and for whom we were able to study prenatal ultrasonography (56 probands), isolated hyperechogenic kidneys with normal or slightly enhanced size were the more frequent (34 of 56) phenotype before birth. Various other prenatal renal phenotypes were associated with HNF1B mutations, at a lesser frequency. Diabetes developed in four probands. Hyperuricemia and hypomagnesemia, although not systematically investigated, were frequently associated. CONCLUSIONS: This large series showed that the severity of the renal disease associated with HNF1B mutations was extremely variable (from prenatal renal failure to normal renal function in adulthood) and was not correlated with the genotype.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Néphrologie Adulte, Néphrologie Pédiatrique, U983

Retrospective French nationwide survey of childhood aggressive vascular anomalies of bone, 1988-2009

HERITIER S, LE MERRER M, JAUBERT F, BIGORRE M, GILLIBERT-YVERT M, DE COURTIVRON B, ZIADE M, BERTRAND Y, CARRIE C, CHASTAGNER P, BOST-BRU C, LEONARD JC, OUACHE M, BOCCON-GIBOD L, MARY P, DE BLIC J, PIN I, WENDLING D, REVILLON Y, HOUDOIN V, FORIN V, LEPOINTE HD, LANGUEPIN J, WAGNON J, EPAUD R, FAUROUX B, DONADIEU J

2010 - Orphanet J Rare Dis 5(.):3

OBJECTIVE: To document the epidemiological, clinical, histological and radiological characteristics of aggressive vascular abnormalities of bone in children. STUDY DESIGN: Correspondents of the French Society of Childhood Malignancies were asked to notify all cases of aggressive vascular abnormalities of bone diagnosed between January 1988 and September 2009. RESULTS: 21 cases were identified; 62% of the patients were boys. No familial cases were observed, and the disease appeared to be sporadic. Mean age at diagnosis was 8.0 years [0.8-16.9 years]. Median follow-up was 3 years [0.3-17 years]. The main presenting signs were bone fracture (n = 4) and respiratory distress (n = 7), but more indolent onset was observed in 8 cases. Lung involvement, with lymphangiectasies and pleural effusion, was the most frequent form of extraosseous involvement (10/21). Bisphosphonates, alpha interferon and radiotherapy were used as potentially curative treatments. High-dose radiotherapy appeared to be effective on pleural effusion but caused major late sequelae, whereas antiangiogenic drugs like alpha interferon and zoledrenate have had a limited impact on the course of pulmonary complications. The impact of bisphosphonates and alpha interferon on bone lesions was also difficult to assess, owing to insufficient follow-up in most cases, but it was occasionally positive. Six deaths were observed and the overall 10-year mortality rate was about 30%. The prognosis depended mainly on pulmonary and spinal complications. CONCLUSION: Aggressive vascular abnormalities of bone are extremely rare in childhood but are lifethreatening. The impact of anti-angiogenic drugs on pulmonary complications seems to be limited, but they may improve bone lesions.

Unité(s) : Anatomie Pathologique, Centre de Génétique Médicale Jean Frézal, Chirurgie Viscérale Pédiatrique, Pneumologie et Asthmologie Pédiatriques

Stickler syndrome caused by COL2A1 mutations: genotype-phenotype correlation in a series of 100 patients

HOORNAERT KP, VEREECKE I, DEWINTER C, ROSENBERG T, BEEMER FA, LEROY JG, BENDIX L, BJORCK E, BONDUELLE M, BOUTE O, CORMIER-DAIRE V, DE DIE-SMULDERS C, DIEUX-COESLIER A, DOLLFUS H, ELTING M, GREEN A, GUERCI VI, HENNEKAM RC, HILHORTS-HOFSTEE Y, HOLDER M, HOYNG C, JONES KJ, JOSIFOVA D, KAITILA I, KJAERGAARD S, KROES YH, LAGERSTEDT K, LEES M, LE MERRER M, MAGNANI C, MARCELIS C, MARTORELL L, MATHIEU M, MCENTAGART M, MENDICINO A, MORTON J, ORAZIO G, PAQUIS V, REISH O, SIMOLA KO, SMITHSON SF, TEMPLE KI, VAN AKEN E, VAN BEVER Y, VAN DEN ENDE J, VAN HAGEN JM, ZELANTE L, ZORDANIA R, DE PAEPE A, LEROY BP, DE BUYZERE M, COUCKE PJ, MORTIER GR

2010 - Eur J Hum Genet 18(8):872-80

Stickler syndrome is an autosomal dominant connective tissue disorder caused by mutations in different collagen genes. The aim of our study was to define more precisely the phenotype and genotype of Stickler syndrome type 1 by investigating a large series of patients with a heterozygous mutation in COL2A1. In 188 probands with the clinical diagnosis of Stickler syndrome, the COL2A1 gene was analyzed by either a mutation scanning technique or bidirectional fluorescent DNA sequencing. The effect of splice site alterations was investigated by analyzing mRNA. Multiplex ligation-dependent amplification analysis was used for the detection of intragenic deletions. We identified 77 different COL2A1 mutations in 100 affected individuals. Analysis of the splice site mutations showed unusual RNA isoforms, most of which contained a premature stop codon. Vitreous anomalies and retinal detachments were found more frequently in patients with a COL2A1 mutation compared with the mutation-negative group (P<0.01). Overall, 20 of 23 sporadic patients with a COL2A1 mutation had either a cleft palate or retinal detachment with vitreous anomalies. The presence of vitreous anomalies, retinal tears or detachments, cleft palate and a positive family history were shown to be good indicators for a COL2A1 defect. In conclusion, we confirm that Stickler syndrome type 1 is predominantly caused by loss-of-function mutations in the COL2A1 gene as >90% of the mutations were predicted to result in nonsense-mediated decay. On the basis of binary regression analysis, we developed a scoring system that may be useful when evaluating patients with Stickler syndrome.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Erratum to: Stickler syndrome caused by COL2A1 mutations: genotype-phenotype correlation in a series of 100 patients

2010 - Eur J Hum Genet 18(8):881

Unité(s) : Centre de Génétique Médicale Jean Frézal

Modifier genes in pseudoxanthoma elasticum: novel insights from the Ggcx mouse model

HOVNANIAN A

2010 - J Mol Med 88(2):149-53

Unité(s) : Centre de Génétique Médicale Jean Frézal

OBSL1 mutations in 3-M syndrome are associated with a modulation of IGFBP2 and IGFBP5 expression levels

HUBER C, FRADIN M, EDOUARD T, LE MERRER M, ALANAY Y, DA SILVA DB, DAVID A, HAMAMY H, VAN HEST L, LUND AM, MICHAUD J, OLEY C, PATEL C, RAJAB A, SKIDMORE DL, STEWART H, TAUBER M, MUNNICH A, CORMIER-DAIRE V

2010 - Hum Mutat 31(1):20-26

3-M syndrome is an autosomal recessive disorder characterized by severe pre- and postnatal growth retardation and minor skeletal changes. We have previously identified CUL7 as a disease-causing gene but we have also provided evidence of genetic heterogeneity in the 3-M syndrome. By homozygosity mapping in two inbred families, we found a second disease locus on chromosome 2q35-36.1 in a 5.2-Mb interval that encompasses 60 genes. To select candidate genes, we performed microarray analysis of cultured skin fibroblast RNA from one patient, looking for genes with altered expression; we found decreased expression of IGFBP2 and increased expression of IGFBP5. However, direct sequencing of these two genes failed to detect any anomaly. We then considered other candidate genes by their function/location and found nine distinct mutations in the OBSL1 gene in 13 families including eight nonsense and one missense mutations. To further understand the links between OBSL1, CUL7, and insulin-like growth factor binding proteins (IGFBPs), we performed real-time quantitative PCR (RT-PCR) analysis for OBSL1, CUL7, IGFBP2, and IGFBP5, using cultured fibroblast RNAs from two patients with distinct OBSL1 mutations (p.F697G; p.H814RfsX15). We found normal CUL7 mRNA levels but abnormal IGFBP2 and IGFBP5 mRNA levels in the two patients, suggesting that OBSL1 modulates the expression of IGFBP proteins. Hum Mutat 30:1-7, 2009. (c) 2009 Wiley-Liss, Inc.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Novel TMEM67 mutations and genotype-phenotype correlates in meckelin-related ciliopathies

IANNICELLI M, BRANCATI F, MOUGOU-ZERELLI S, MAZZOTTA A, THOMAS S, ELKHARTOUFI N, TRAVAGLINI L, GOMES C, LUIGI ARDISSINO G, BERTINI E, BOLTSHAUSER E, CASTORINA P, D'ARRIGO S, FISCHETTO R, LEROY B, LOGET P, BONNIERE M, STARCK L, TANTAU J, GENTILIN B, MAJORE S, SWISTUN D, FLORI E, LALATTA F, PANTALEONI C, PENZIEN J, GRAMMATICO P, THE INTERNATIONAL JSG, DALLAPICCOLA B, GLEESON JG, ATTIE-BITACH T, VALENTE EM

2010 - Hum Mutat 31(5):E1319-31

Human ciliopathies are hereditary conditions caused by defects of proteins expressed at the primary cilium. Among ciliopathies, Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS) and nephronophthisis (NPH) present clinical and genetic overlap, being allelic at several loci. One of the most interesting gene is TMEM67, encoding the transmembrane protein meckelin. We performed mutation analysis of TMEM67 in 341 probands, including 265 JSRD representative of all clinical subgroups and 76 MKS fetuses. We identified 33 distinct mutations, of which 20 were novel, in 8/10 (80%) JS with liver involvement (COACH phenotype) and 12/76 (16%) MKS fetuses. No mutations were found in other JSRD subtypes, confirming the strong association between TMEM67 mutations and liver involvement. Literature review of all published TMEM67mutated cases was performed to delineate genotype-phenotype correlates. In particular, comparison of the types of mutations and their distribution along the gene in lethal versus non lethal phenotypes showed in MKS patients a significant enrichment of missense mutations falling in TMEM67 exons 8 to 15, especially when in combination with a truncating mutation. These exons encode for a region of unknown function in the extracellular domain of meckelin. (c) 2010 Wiley-Liss, Inc.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Clinical variability of familial tumoral calcinosis caused by novel GALNT3 mutations

ICHIKAWA S, BAUJAT G, SEYAHI A, GAROUFALI AG, IMEL EA, PADGETT LR, AUSTIN AM, SORENSON AH, PEJIN Z, TOPOUCHIAN V, QUARTIER P, CORMIER-DAIRE V, DECHAUX M, MALANDRINOU F, SINGHELLAKIS PN, LE MERRER M, ECONS MJ

2010 - Am J Med Genet A 152A(4):896-903

The GALNT3 gene encodes GalNAc-T3, which prevents degradation of the phosphaturic hormone, fibroblast growth factor 23 (FGF23). Biallelic mutations in either GALNT3 or FGF23 result in hyperphosphatemic familial tumoral calcinosis or its variant, hyperostosis-hyperphosphatemia syndrome. Tumoral calcinosis is characterized by the presence of ectopic calcifications around major joints, whereas hyperostosis-hyperphosphatemia syndrome is characterized by recurrent long bone lesions with hyperostosis. Here we investigated four patients with hyperphosphatemia and clinical manifestations including tumoral calcinosis and/or hyperostosis-hyperphosphatemia syndrome to determine underlying genetic cause and delineate phenotypic heterogeneity of these disorders. Mutational analysis of FGF23 and GALNT3 in these patients revealed novel homozygous mutations in GALNT3. Although the presence of massive calcifications, cortical hyperostosis, or dental anomalies was not shared by all patients, all had persistent hyperphosphatemia. Three of the patients also had inappropriately normal 1,25-dihyroxyvitamin D [1,25(OH)(2)D] and confirmed low circulating intact FGF23 concentrations. The four novel GALNT3 mutations invariably resulted in hyperphosphatemia as a result of low intact FGF23, but other clinical manifestations were variable. Therefore, tumoral calcinosis and hyperostosis-hyperphosphatemia syndrome represent a continuous spectrum of the same disease caused by increased phosphate levels, rather than two distinct disorders.

Unité(s) : Centre de Génétique Médicale Jean Frézal,Explorations Fonctionnelles,Immunologie-Hématologie Pédiatriques,Traumatologie et Orthopédie Pédiatriques

Axial spondylometaphyseal dysplasia: Confirmation and further delineation of a new SMD with retinal dystrophy

ISIDOR B, BARON S, KHAU VAN KIEN P, BERTRAND AM, DAVID A, LE MERRER M

2010 - Am J Med Genet A 152A(6):1550-4

This report describes two unrelated boys presenting with short stature, femoral metaphyseal abnormalities, platyspondyly, and retinitis pigmentosa. Patients share similar findings with cases described by Ehara et al. [Ehara et al. (1997); Eur J Pediatr 156:627-630] described as axial spondylometaphyseal dysplasia. The presence of consanguinity in one of our patients further supports an autosomal recessive mode of inheritance of what, we believe, constitutes a separate and distinct entity.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Rubinstein-Taybi syndrome and Hirschsprung disease in a patient harboring an intragenic deletion of the CREBBP gene

ISIDOR B, PODEVIN G, CAMBY C, MOSNIER JF, CHAUTY A, LYET JM, FERGELOT P, LACOMBE D, ARVEILER B, PELET A, AMIEL J, DAVID A

2010 - Am J Med Genet A 152A(7):1847-8

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Heterozygous FIC1 Deficiency: A New Genetic Predisposition to Transient Neonatal Cholestasis

JACQUEMIN E, MALAN V, RIO M, DAVIT-SPRAUL A, COHEN J, LANDRIEU P, BERNARD O

2010 - J Pediatr Gastroenterol Nutr 50(4):447-49

Unité(s) : Centre de Génétique Médicale Jean Frézal

Stüve–Wiedemann syndrome: long-term follow-up and genetic heterogeneity

JUNG C, DAGONEAU N, BAUJAT G, LE MERRER M, DAVID A, DI ROCCO M, HAMEL B, MEGARBANE A, SUPERTI-FURGA A, UNGER S, MUNNICH A, CORMIER-DAIRE V

2010 - Clin. Genet. 77(3):266-272

Stüve–Wiedemann syndrome (SWS, OMIM 601559) is a severe autosomal recessive condition caused by mutations in the leukemia inhibitory receptor (LIFR) gene. The main characteristic features are bowing of the long bones, neonatal respiratory distress, swallowing/sucking difficulties and dysautonomia symptoms including temperature instability often leading to death in the first years of life. We report here four patients with SWS who have survived beyond 36 months of age with no LIFR mutation. These patients have been compared with six unreported SWS survivors carrying null LIFR mutations. We provide evidence of clinical homogeneity of the syndrome in spite of the genetic heterogeneity.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Mutation update for the CSB/ERCC6 and CSA/ERCC8 genes involved in Cockayne syndrome

LAUGEL V, DALLOZ C, DURAND M, SAUVANAUD F, KRISTENSEN U, VINCENT MC, PASQUIER L, ODENT S, CORMIER-DAIRE V, GENER B, TOBIAS ES, TOLMIE JL, MARTIN-COIGNARD D, DROUIN-GARRAUD V, HERON D, JOURNEL H, RAFFO E, VIGNERON J, LYONNET S, MURDAY V, GUBSER-MERCATI D, FUNALOT B, BRUETON L, SANCHEZ-DEL POZO J, MUNOZ E, GENNERY AR, SALIH M, NORUZINIA M, PRESCOTT K, RAMOS L, STARK Z, FIEGGEN K, CHABROL B, SARDA P, EDERY P, BLOCH-ZUPAN A, FAWCETT H, PHAM D, EGLY JM, LEHMANN AR, SARASIN A, DOLLFUS H

2010 - Hum Mutat 31(2):113-26

Cockayne syndrome is an autosomal recessive multisystem disorder characterized principally by neurological and sensory impairment, cachectic dwarfism, and photosensitivity. This rare disease is linked to mutations in the CSB/ERCC6 and CSA/ERCC8 genes encoding proteins involved in the transcription-coupled DNA repair pathway. The clinical spectrum of Cockayne syndrome encompasses a wide range of severity from severe prenatal forms to mild and late-onset presentations. We have reviewed the 45 published mutations in CSA and CSB to date and we report 43 new mutations in these genes together with the corresponding clinical data. Among the 84 reported kindreds, 52 (62%) have mutations in the CSB gene. Many types of mutations are scattered along the whole coding sequence of both genes, but clusters of missense mutations can be recognized and highlight the role of particular motifs in the proteins. Genotype-phenotype correlation hypotheses are considered with regard to these new molecular and clinical data. Additional cases of molecular prenatal diagnosis are reported and the strategy for prenatal testing is discussed. Two web-based locus-specific databases have been created to list all identified variants and to allow the inclusion of future reports (www.umd.be/CSA/ and www.umd.be/CSB/).

Unité(s) : Centre de Génétique Médicale Jean Frézal

Genotype-Phenotype Correlations in Non-Finnish Congenital Nephrotic Syndrome

MACHUCA E, BENOIT G, NEVO F, TETE MJ, GRIBOUVAL O, PAWTOWSKI A, BRANDSTROM P, LOIRAT C, NIAUDET P, GUBLER MC, ANTIGNAC C

2010 - J Am Soc Nephrol 27(7):1209-17

Mutations in NPHS1, which encodes nephrin, are the main causes of congenital nephrotic syndrome (CNS) in Finnish patients, whereas mutations in NPHS2, which encodes podocin, are typically responsible for childhood-onset steroid-resistant nephrotic syndrome in European populations. Genotype-phenotype correlations are not well understood in non-Finnish patients. We evaluated the clinical presentation, kidney histology, and disease progression in non-Finnish CNS cases by mutational screening in 107 families (117 cases) by sequencing the entire coding regions of NPHS1, NPHS2, PLCE1, WT1, LAMB2, PDSS2, COQ2, and NEPH1. We found that CNS describes a heterogeneous group of disorders in non-Finnish populations. We identified nephrin and podocin mutations in most families and only rarely found mutations in genes implicated in other hereditary forms of NS. In approximately 20% of cases, we could not identify the underlying genetic cause. Consistent with the major role of nephrin at the slit diaphragm, NPHS1 mutations associated with an earlier onset of disease and worse renal outcomes than NPHS2 mutations. Milder cases resulting from mutant NPHS1 had either two mutations in the cytoplasmic tail or two missense mutations in the extracellular domain, including at least one that preserved structure and function. In addition, we extend the spectrum of known NPHS1 mutations by describing long NPHS1 deletions. In summary, these data demonstrate that CNS is not a distinct clinical entity in non-Finnish populations but rather a clinically and genetically heterogeneous group of disorders.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Néphrologie Pédiatrique, U983

Array-based comparative genomic hybridization identifies a high frequency of copy number variations in patients with syndromic overgrowth

MALAN V, CHEVALLIER S, SOLER G, COUBES C, LACOMBE D, PASQUIER L, SOULIER J, MORICHON-DELVALLEZ N, TURLEAU C, MUNNICH A, ROMANA S, VEKEMANS M, CORMIER-DAIRE V, COLLEAUX L

2010 - Eur J Hum Genet 18(2):227-32

Overgrowth syndromes are a heterogeneous group of conditions including endocrine hormone disorders, several genetic syndromes and other disorders with unknown etiopathogenesis. Among genetic causes, chromosomal deletions and duplications such as dup(4)(p16.3), dup(15)(q26qter), del(9)(q22.32q22.33), del(22)(q13) and del(5)(q35) have been identified in patients with overgrowth. Most of them, however, remain undetectable using banding karyotype analysis. In this study, we report on the analysis using a 1-Mb resolution array-based comparative genomic hybridization (CGH) of 93 patients with either a recognizable overgrowth condition (ie, Sotos syndrome or Weaver syndrome) or an unclassified overgrowth syndrome. Five clinically relevant imbalances (three duplications and two deletions) were identified and the pathogenicity of two additional anomalies (one duplication and one deletion) is discussed. Altered segments ranged in size from 0.32 to 18.2 Mb, and no recurrent abnormality was identified. These results show that array-CGH provides a high diagnostic yield in patients with overgrowth syndromes and point to novel chromosomal regions associated with these conditions. Although chromosomal deletions are usually associated with growth retardation, we found that the majority of the imbalances detected in our patients are duplications. Besides their importance for diagnosis and genetic counseling, our results may allow to delineate new contiguous gene syndromes associated with overgrowth, pointing to new genes, the deregulation of which may be responsible for growth defect.

Unité(s) : U781, Centre de Génétique Médicale Jean Frézal

Fourth case of cerebral, ocular, dental, auricular, skeletal syndrome (CODAS), description of new features and molecular analysis

MARLIN S, DUCOU-LE POINTE H, LE MERRER M, PORTNOI MF, CHANTOT S, JONARD L, MANTEL-GUIOCHON A, SIFFROI JP, GARABEDIAN EN, DENOYELLE F

2010 - Am J Med Genet A 152A(6):1510-4

Cerebral, ocular, dental, auricular, skeletal syndrome (CODAS, OMIM 600373) is a very rare congenital malformation syndrome. This clinical entity is highly distinctive and associates mental retardation, cataract, enamel abnormalities, malformations of the helix, epiphyseal and vertebral malformations, and characteristic dysmorphic features. Since 1991, only three affected children have been reported. The etiology and pattern of inheritance of CODAS syndrome still remain unknown. We describe a new sporadic case presenting with all the characteristic features of CODAS syndrome associated with previously unreported malformations of the heart, larynx, and liver. All investigations such as karyotype, metabolic screening and array CGH were normal.

Unité(s) : Centre de Génétique Médicale Jean Frézal

PAX2 mutations in fetal renal hypodysplasia

MARTINOVIC-BOURIEL J, BENACHI A, BONNIERE M, BRAHIMI N, ESCULPAVIT C, MORICHON N, VEKEMANS M, ANTIGNAC C, SALOMON R, ENCHA-RAZAVI F, ATTIE-BITACH T, GUBLER MC

2010 - Am J Med Genet A 152A(4):830-5

Papillorenal syndrome also known as renal-coloboma syndrome (OMIM 120330) is an autosomal dominant condition comprising optic nerve anomaly and renal oligomeganephronic hypoplasia. This reduced number of nephron generations with compensatory glomerular hypertrophy leads towards chronic insufficiency with renal failure. We report on two fetuses with PAX2 mutations presenting at 24 and 18 weeks' gestation, respectively, born into two different sibships. In our first patient, termination of pregnancy was elected for anhydramnios and suspicion of renal agenesis in the healthy couple with an unremarkable previous clinical history. This fetus had bilateral asymmetric kidney anomalies including a small multicystic left kidney, and an extremely hypoplastic right kidney. Histology showed dysplastic lesions in the left kidney, contrasting with rather normal organization in the hypoplastic right kidney. Ocular examination disclosed bilateral optic nerve coloboma. The association of these anomalies, highly suggestive of the papillorenal syndrome, led us to perform the molecular study of the PAX2 gene. Direct sequencing of the PAX2 coding sequence identified a de novo single G deletion of nucleotide 935 in exon 3 of the PAX2 resulting in a frameshift mutation (c.392delG, p.Ser131Thrfs*28). In the second family, the presence of a maternally inherited PAX2 mutation led to a decision for termination of pregnancy. The 18-week gestation fetus presented the papillorenal syndrome including hypoplastic kidneys and optic nerve coloboma. In order to address the PAX2 involvement in isolated renal "disease," 18 fetuses fulfilling criteria were screened: 10/18 had uni- or bilateral agenesis, 6/18 had bilateral multicystic dysplasia with enlarged kidneys, and 2/18 presented bilateral severe hypodysplasia confirmed on fetopathological examination. To the best of our knowledge, our first patient represents an unreported fetal diagnosis of papillorenal syndrome, and another example of the impact of oriented fetopathological examination in genetic counseling of the parents.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Histo-Embryologie - Cytogénétique, Néphrologie Pédiatrique, Obstétrique, U983, U781

Identification of 28 novel mutations in the Bardet-Biedl syndrome genes: the burden of private mutations in an extensively heterogeneous disease

MULLER J, STOETZEL C, VINCENT MC, LEITCH CC, LAURIER V, DANSE JM, HELLE S, MARION V, BENNOUNA-GREENE V, VICAIRE S, MEGARBANE A, KAPLAN J, DROUIN-GARRAUD V, HAMDANI M, SIGAUDY S, FRANCANNET C, ROUME J, BITOUN P, GOLDENBERG A, PHILIP N, ODENT S, GREEN J, COSSEE M, DAVIS EE, KATSANIS N, BONNEAU D, VERLOES A, POCH O, MANDEL JL, DOLLFUS H

2010 - Hum Genet 127(5):583-93

Bardet-Biedl syndrome (BBS), an emblematic disease in the rapidly evolving field of ciliopathies, is characterized by pleiotropic clinical features and extensive genetic heterogeneity. To date, 14 BBS genes have been identified, 3 of which have been found mutated only in a single BBS family each (BBS11/TRIM32, BBS13/MKS1 and BBS14/MKS4/NPHP6). Previous reports of systematic mutation detection in large cohorts of BBS families (n > 90) have dealt only with a single gene, or at most small subsets of the known BBS genes. Here we report extensive analysis of a cohort of 174 BBS families for 12/14 genes, leading to the identification of 28 novel mutations. Two pathogenic mutations in a single gene have been found in 117 families, and a single heterozygous mutation in 17 families (of which 8 involve the BBS1 recurrent mutation, M390R). We confirm that BBS1 and BBS10 are the most frequently mutated genes, followed by BBS12. No mutations have been found in BBS11/TRIM32, the identification of which as a BBS gene only relies on a single missense mutation in a single consanguineous family. While a third variant allele has been observed in a few families, they are in most cases missenses of uncertain pathogenicity, contrasting with the type of mutations observed as two alleles in a single gene. We discuss the various strategies for diagnostic mutation detection, including homozygosity mapping and targeted arrays for the detection of previously reported mutations.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Renal phenotype of the cystinosis mouse model is dependent upon genetic background

NEVO N, CHOL M, BAILLEUX A, KALATZIS V, MORISSET L, DEVUYST O, GUBLER MC, ANTIGNAC C

2010 - Nephrol Dial Transplant 25(4):1059-66

BACKGROUND: Cystinosis is caused by mutations in CTNS that encodes cystinosin, the lysosomal cystine transporter. The most severe and frequent form is characterized by a proximal tubulopathy that appears around 6 to 12 months of age. In the absence of treatment, end-stage renal disease is reached by 10 years. Ctns(-/-) mice of a mixed 129Sv x C57BL/6 genetic background show elevated renal cystine levels; however, proximal tubulopathy or end-stage renal disease is not observed. METHODS: As renal phenotype can be influenced by genetic background, we generated congenic C57BL/6 and FVB/N Ctns(-/-) mice and assayed renal lesions and function by histological and biochemical studies. RESULTS: C57BL/6 Ctns(-/-) mice showed significantly higher renal cystine levels than the FVB/N strain. Moreover, C57BL/6 mice presented with pronounced histological lesions of the proximal tubules as well as a tubulopathy and progressively developed chronic renal failure. In contrast, renal dysfunction was not observed in the FVB/N strain. CONCLUSIONS: Thus, the C57BL/6 strain represents the first Ctns(-/-) mouse model to show clear renal defects. In addition to highlighting the influence of genetic background on phenotype, the C57BL/6 Ctns(-/-) mice represent a useful model for further understanding cystinosin function in the kidney and, specifically, in the proximal tubules.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U983

Individuals with mutations in XPNPEP3, which encodes a mitochondrial protein, develop a nephronophthisis-like nephropathy

O'TOOLE JF, LIU Y, DAVIS EE, WESTLAKE CJ, ATTANASIO M, OTTO EA, SEELOW D, NURNBERG G, BECKER C, NUUTINEN M, KARPPA M, IGNATIUS J, UUSIMAA J, PAKANEN S, JAAKKOLA E, VAN DEN HEUVEL LP, FEHRENBACH H, WIGGINS R, GOYAL M, ZHOU W, WOLF MT, WISE E, HELOU J, ALLEN SJ, MURGA-ZAMALLOA CA, ASHRAF S, CHAKI M, HEERINGA S, CHERNIN G, HOSKINS BE, CHAIB H, GLEESON J, KUSAKABE T, SUZUKI T, ISAAC RE, QUARMBY LM, TENNANT B, FUJIOKA H, TUOMINEN H, HASSINEN I, LOHI H, VAN HOUTEN JL, ROTIG A, SAYER JA, ROLINSKI B, FREISINGER P, MADHAVAN SM, HERZER M, MADIGNIER F, PROKISCH H, NURNBERG P, JACKSON P, KHANNA H, KATSANIS N, HILDEBRANDT F

2010 - J Clin Invest 120(3):791-802

The autosomal recessive kidney disease nephronophthisis (NPHP) constitutes the most frequent genetic cause of terminal renal failure in the first 3 decades of life. Ten causative genes (NPHP1-NPHP9 and NPHP11), whose products localize to the primary cilia-centrosome complex, support the unifying concept that cystic kidney diseases are "ciliopathies". Using genome-wide homozygosity mapping, we report here what we believe to be a new locus (NPHP-like 1 [NPHPL1]) for an NPHP-like nephropathy. In 2 families with an NPHP-like phenotype, we detected homozygous frameshift and splice-site mutations, respectively, in the X-prolyl aminopeptidase 3 (XPNPEP3) gene. In contrast to all known NPHP proteins, XPNPEP3 localizes to mitochondria of renal cells. However, in vivo analyses also revealed a likely cilia-related function; suppression of zebrafish xpnpep3 phenocopied the developmental phenotypes of ciliopathy morphants, and this effect was rescued by human XPNPEP3 that was devoid of a mitochondrial localization signal. Consistent with a role for XPNPEP3 in ciliary function, several ciliary cystogenic proteins were found to be XPNPEP3 substrates, for which resistance to N-terminal proline cleavage resulted in attenuated protein function in vivo in zebrafish. Our data highlight an emerging link between mitochondria and ciliary dysfunction, and suggest that further understanding the enzymatic activity and substrates of XPNPEP3 will illuminate novel cystogenic pathways.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Gestational age-related reference values for amniotic fluid organic acids

OTTOLENGHI C, ABERMIL N, LESCOAT A, AUPETIT J, BEAUGENDRE O, MORICHON-DELVALLEZ N, RICQUIER D, CHADEFAUX-VEKEMANS B, RABIER D

2010 - Prenat Diagn 30(1):43-48

BACKGROUND: Normative data for amniotic fluid (AF) levels of organic acids at different gestational ages are lacking. They can provide a useful framework to investigate the accuracy of prenatal diagnosis for organic acidemias. METHODS: We report on the concentration of 21 organic acids in AF obtained by gas chromatography/mass spectrometry between the 12th and 34th weeks of gestation from 92 pregnancies that were not at risk for organic acidurias. RESULTS: We infer normal reference values that can be compared with 134 pregnancies at risk for several metabolic conditions, that is, propionic acidemia, methylmalonic acidemia (methylmalonyl-CoA mutase deficiency or defects in cobalamin metabolism), 4-hydroxybutyric acidemia, glutaric acidemia and pyroglutamic acidemia. CONCLUSION: Most of the metabolites tested did not show conspicuous variations across gestational ages in normal fetuses, with ranges that were consistently similar to available reference values from pooled samples in previous reports. With rare exceptions, knowledge of pathological versus normal values for relevant metabolites leads to clear-cut differentiation of affected versus unaffected fetuses. Nevertheless, it is strongly recommended that mutational analysis and/or additional biochemical approaches complement organic acid analysis for an adequate diagnostic workup. Copyright (c) 2009 John Wiley & Sons, Ltd.

Unité(s) : Biochimie Métabolique, Centre de Génétique Médicale Jean Frézal

Immune reactivity to type VII collagen: implications for gene therapy of recessive dystrophic epidermolysis bullosa

PENDARIES V, GASC G, TITEUX M, LEROUX C, VITEZICA ZG, MEJIA JE, DECHA A, LOISEAU P, BODEMER C, PROST-SQUARCIONI C, HOVNANIAN A

2010 - Gene Ther 17(7):930-37

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe genodermatosis caused by loss-of-function mutations in COL7A1 encoding type VII collagen, the component of anchoring fibrils. As exogenous type VII collagen may elicit a deleterious immune response in RDEB patients during upcoming clinical trials of gene therapies or protein replacement therapies, we developed enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunosorbent spot (ELISPOT) assays to analyze B- and T-cell responses, to the full-length type VII collagen. The ELISA was highly sensitive and specific when tested against sera from 41 patients with epidermolysis bullosa acquisita (EBA), and the IFN-gamma ELISPOT detected a cellular response that correlated with ongoing EBA manifestations. Both tests were next applied to assess the risk of an immune response to type VII collagen in seven RDEB patients with a range of type VII collagen expression profiles. Immune responses against type VII collagen were dependent on the expression of type VII collagen protein, and consequently on the nature and position of the respective COL7A1 mutations. These immunologic tests will be helpful for the selection of RDEB patients for future clinical trials aiming at restoring type VII collagen expression, and in monitoring their immune response to type VII collagen after treatment.Gene Therapy advance online publication, 8 April 2010; doi:10.1038/gt.2010.36.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Dermatologie

A murine model of denys-drash syndrome reveals novel transcriptional targets of WT1 in podocytes

RATELADE J, ARRONDEL C, HAMARD G, GARBAY S, HARVEY S, BIEBUYCK N, SCHULZ H, HASTIE N, PONTOGLIO M, GUBLER MC, ANTIGNAC C, HEIDET L

2010 - Hum Mol Genet 19(1):1-15

The Wilms tumor-suppressor gene WT1, a key player in renal development, also has a crucial role in maintenance of the glomerulus in the mature kidney. However, molecular pathways orchestrated by WT1 in podocytes, where it is highly expressed, remain unknown. Their defects are thought to modify the cross-talk between podocytes and other glomerular cells and ultimately lead to glomerular sclerosis, as observed in diffuse mesangial sclerosis (DMS) a nephropathy associated with WT1 mutations. To identify podocyte WT1 targets, we generated a novel DMS mouse line, performed gene expression profiling in isolated glomeruli, and identified excellent candidates that may modify podocyte differentiation and growth factor signalling in glomeruli. Scel, encoding sciellin, a protein of the cornified envelope in the skin, and sulf1, encoding a 6-O endosulfatase, are shown to be expressed in wild type podocytes and to be strongly down-regulated in mutants. Co-expression of Wt1, Scel and Sulf1 was also found in a mesonephric cell line, and siRNA-mediated knockdown of WT1 decreased Scel and Sulf1 mRNAs and proteins. By ChIP we show that Scel and Sulf1 are direct WT1 targets. Cyp26a1, encoding an enzyme involved in the degradation of retinoic acid, is shown to be up-regulated in mutant podocytes. Cyp26a1 may play a role in the development of glomerular lesions but does not seem to be regulated by WT1. These results provide novel clues in our understanding of normal glomerular function and early events involved in glomerulosclerosis.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U983

Additional clinical and molecular analyses of TFAP2A in patients with the branchio-oculo-facial syndrome

REIBER J, SZNAJER Y, POSTEGUILLO EG, MULLER D, LYONNET S, BAUMANN C, JUST W

2010 - Am J Med Genet A 152A(4):994-9

The branchio-oculo-facial syndrome (BOFS) is a rare disorder with approximately 50 sporadic and familial cases in the literature. We report on the clinical and molecular analyses of five additional patients with BOFS (two familial and three sporadic). DNA analysis of the TFAP2A gene associated with BOFS using DNA sequencing detected a mutation [c.763A>G (p.Arg255Gly)] in two unrelated patients. This mutation had been reported in another patient and indicates a probable mutational hotspot in the TFAP2A gene. We also detected three new mutations which are restricted to exons 4-6. These gene regions are almost free of any single nucleotide polymorphisms. An evolutionary sequence comparison showed a high degree of sequence conservation from humans to the honey bee (Apis mellifera) in exon 6 showing that this part of the protein is probably essential. Our study represents the second group of BOFS patients with molecular confirmation, expanding the phenotype and spectrum of mutations and limiting it to a restricted part of the gene.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Mitochondrial ND5 mutations mimicking brainstem tectal glioma

RIO M, LEBRE AS, DE LONLAY P, VALAYANNOPOULOS V, DESGUERRE I, DUFIER JL, GREVENT D, ZILBOVICIUS M, TREGUIER C, BRUNELLE F, DE BARACE C, KAPLAN J, ESPINASE-BERROD MA, SAINTE-ROSE C, PUGET S, ROTIG A, MUNNICH A, BODDAERT N

2010 - Neurology 75(1):93

Unité(s) : Centre de Génétique Médicale Jean Frézal, Métabolisme, Neurochirurgie Pédiatrique, Neurologie, Ophtalmologie, Radiologie Pédiatrique

Familial interstitial Xq27.3q28 duplication encompassing the FMR1 gene but not the MECP2 gene causes a new syndromic mental retardation condition

RIO M, MALAN V, BOISSEL S, TOUTAIN A, ROYER G, GOBIN S, MORICHON-DELVALLEZ N, TURLEAU C, BONNEFONT JP, MUNNICH A, VEKEMANS M, COLLEAUX L

2010 - Eur J Hum Genet 18(3):285-290

X-linked mental retardation is a common disorder that accounts for 5-10% of cases of mental retardation in males. Fragile X syndrome is the most common form resulting from a loss of expression of the FMR1 gene. On the other hand, partial duplication of the long arm of the X chromosome is uncommon. It leads to functional disomy of the corresponding genes and has been reported in several cases of mental retardation in males. In this study, we report on the clinical and genetic characterization of a new X-linked mental retardation syndrome characterized by short stature, hypogonadism and facial dysmorphism, and show that this syndrome is caused by a small Xq27.3q28 interstitial duplication encompassing the FMR1 gene. This family broadens the phenotypic spectrum of FMR1 anomalies in an unexpected manner, and we suggest that this condition may represent the fragile X syndrome <>.European Journal of Human Genetics advance online publication, 21 October 2009; doi:10.1038/ejhg.2009.159.

Unité(s) : U781, Centre de Génétique Médicale Jean Frézal

Germline mosaicism in keratitis-ichthyosis-deafness syndrome: pre-natal diagnosis in a familial lethal form

SBIDIAN E, FELDMANN D, BENGOA J, FRAITAG S, ABADIE V, DE PROST Y, BODEMER C, HADJ-RABIA S

2010 - Clin Genet 77(6):587-92

Sbidian E, Feldmann D, Bengoa J, Fraitag S, Abadie V, de Prost Y, Bodemer C, Hadj-Rabia S. Germline mosaicism in keratitis-ichthyosis-deafness syndrome: pre-natal diagnosis in a familial lethal form. Keratitis-ichthyosis-deafness (KID) syndrome is an autosomal dominant congenital ectodermal defect characterized by the association of skin lesions, hearing loss and keratitis. Most of the cases appear to be sporadic. KID syndrome is mostly related to mutations of GJB2 gene encoding connexin-26. Recently, a lethal form of the disease during the first year of life has been reported in two unrelated Caucasian patients. This rare lethal form is caused by the G45E mutation of GJB2 gene. We here report the first pre-natal molecular genetic diagnosis of the lethal form of KID syndrome relating to a G45E mutation. In the same family, the occurrence of this condition in three other siblings born to African non-consanguineous healthy parents lead to perform pre-natal diagnosis for this last pregnancy. Molecular analysis confirms the diagnosis of the lethal form of KID for the fetus. These results establish the role of germline mosaicism in KID syndrome and warrant careful genetic counseling. Furthermore, analysis of our cases and the literature allowed us to define a characteristic severe neonatal phenotype including facial dysmorphy, severe cornification with massive focal hyperkeratosis of the skin with erythroderma, dystrophic nails, complete atrichia and absence of foreskin.

Unité(s) : Anatomie Pathologique, Centre de Génétique Médicale Jean Frézal, Dermatologie, Pédiatrie Générale

Postnatal growth retardation, facial dysmorphism, spondylocarpal synostosis, cardiac defect, and inner ear malformation (cardiospondylocarpofacial syndrome?)-A distinct syndrome?

SOUSA SB, BAUJAT G, ABADIE V, BONNET D, SIDI D, MUNNICH A, KRAKOW D, CORMIER-DAIRE V

2010 - Am J Med Genet A 152A(3):539-546

We report on two unrelated cases born to nonconsanguineous parents with a similar clinical presentation: hypotonia since the neonatal period, severe failure to thrive, postnatal growth retardation, facial dysmorphism, congenital cardiac defects (septal defect and non progressive multiple valve dysplasia), shortened extremities, carpal/tarsal and extensive vertebral synostosis, delayed carpal bone age, deafness, and inner ear malformations. Presently, both patients present with normal psychomotor development. Additional abnormal findings include extra oral frenulum, nasal speech, and vesico-ureteral reflux. Molecular analysis in one patient excluded the Noggin gene and Filamin B (FLNB) was excluded in the other patient. Although some features are similar to spondylocarpotarsal synostosis syndrome, the exclusion of FLNB and this constellation of findings suggest a new entity, closely similar to an autosomal dominant condition reported by Forney et al. 1966 in a unique family. Identification of similarly affected patients should aid in the further elucidation of this syndrome. (c) 2010 Wiley-Liss, Inc.

Unité(s) : Cardiologie Pédiatrique, Centre de Génétique Médicale Jean Frézal, Pédiatrie Générale, U781

Gene therapy for recessive dystrophic epidermolysis bullosa

TITEUX M, PENDARIES V, HOVNANIAN A

2010 - Dermatol Clin 28(2):361-6

Among the severe genetic disorders of the skin that are suitable for gene and cell therapy, most efforts have been made in the treatment of blistering diseases including dystrophic epidermolysis bullosa. This condition can be recessively or dominantly inherited, depending on the nature and position of the mutation or mutations in the gene encoding type VII collagen. At present, there is no specific treatment for recessive dystrophic epidermolysis bullosa, and gene and cell therapy approaches hold great promise. This article discusses the different gene therapy approaches that have been used for the treatment of this disease and the new perspectives that they open.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Dermatologie

[Trisomy 21: fifty years between medicine and science.]

TURLEAU C, VEKEMANS M

2010 - Med Sci (Paris) 26(3):267-72

Fifty years after the discovery of the etiology of Down syndrome, trisomy 21 remains the model of choice for studying human diseases resulting from the presence of a chromosome or a chromosome segment in excess. In this review, mechanisms of aneuploidy occurrence and consequences of genomic imbalances will be mainly discussed. The study of genetic markers showed that trisomy 21 results in 90% of cases from an error during maternal meiosis. Approximately 8% of cases result from an error during paternal meiosis and in 2% of cases there is a postzygotic mitotic nondisjunction. The biological basis of the effect of maternal age remains largely unknown. The absence of genetic recombination between homologous chromosomes or the presence of an exchange in telomeric position are two risk factors of non-disjunction observed in young women. Non-disjunctions associated with pericentromeric exchanges are observed with an increase in maternal age. The study of mouse models and patients with partial trisomy 21, combined with advances in knowledge of the physical map and the transcriptome, identified genes directly or indirectly involved in the pathogenesis of Down syndrome. The recent description of metabolic pathways controlled by RCAN1 and DYRK1A genes which may be involved in many biological processes and phenotypes associated with trisomy 21 allows to consider new therapeutic strategies.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Histo-Embryologie - Cytogénétique

Cognitive and neuroradiological improvement in three patients with attenuated MPS I treated by laronidase

VALAYANNOPOULOS V, BODDAERT N, BARBIER V, LE MERRER M, CAILLAUD C, DE LONLAY P

2010 - Mol Genet Metab 100(1):20-23

Stem cell transplantation is not appropriate first-line treatment for attenuated phenotypes of mucopolysaccharidosis type I (MPS I). In three patients with attenuated MPSA I treated by laronidase, Patients 2 and 3 displayed significant cognitive improvement within 2years; Patients 1 and 3 displayed improvement on MRI scans of the brain.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Métabolisme, Radiologie Pédiatrique

New SUCLG1 patients expanding the phenotypic spectrum of this rare cause of mild methylmalonic aciduria

VALAYANNOPOULOS V, HAUDRY C, SERRE V, BARTH M, BODDAERT N, ARNOUX JB, CORMIER-DAIRE V, RIO M, RABIER D, VASSAULT A, MUNNICH A, BONNEFONT JP, DE LONLAY P, ROTIG A, LEBRE AS

2010 - Mitochondrion 10(4):335-41

Deficiencies in two subunits of the succinyl-coenzyme A synthetase (SCS) have been involved in patients with encephalomyopathy and mild methylmalonic aciduria (MMA). In this study, we described three new SUCLG1 patients and performed a meta-analysis of the literature. Our report enlarges the phenotypic spectrum of SUCLG1 mutations and confirms that a characteristic metabolic profile (presence of MMA and C4-DC carnitine in urines) and basal ganglia MRI lesions are the hallmarks of SCS defects. As mitochondrial DNA depletion in muscle is not a constant finding in SUCLG1 patients, this may suggest that diagnosis should not be based on it, but also that alternative physiopathological mechanisms may be considered to explain the combined respiratory chain deficiency observed in SCS patients.

Unité(s) : Biochimie Métabolique, Centre de Génétique Médicale Jean Frézal, Métabolisme, Radiologie Pédiatrique, U781

Mutations in TMEM216 perturb ciliogenesis and cause Joubert, Meckel and related syndromes

VALENTE EM, LOGAN CV, MOUGOU-ZERELLI S, LEE JH, SILHAVY JL, BRANCATI F, IANNICELLI M, TRAVAGLINI L, ROMANI S, ILLI B, ADAMS M, SZYMANSKA K, MAZZOTTA A, LEE JE, TOLENTINO JC, SWISTUN D, SALPIETRO CD, FEDE C, GABRIEL S, RUSS C, CIBULSKIS K, SOUGNEZ C, HILDEBRANDT F, OTTO EA, HELD S, DIPLAS BH, DAVIS EE, MIKULA M, STROM CM, BEN-ZEEV B, LEV D, SAGIE TL, MICHELSON M, YARON Y, KRAUSE A, BOLTSHAUSER E, ELKHARTOUFI N, ROUME J, SHALEV S, MUNNICH A, SAUNIER S, INGLEHEARN C, SAAD A, ALKINDY A, THOMAS S, VEKEMANS M, DALLAPICCOLA B, KATSANIS N, JOHNSON CA, ATTIE-BITACH T, GLEESON JG

2010 - Nat Genet 42(7):619-25

Joubert syndrome (JBTS), related disorders (JSRDs) and Meckel syndrome (MKS) are ciliopathies. We now report that MKS2 and CORS2 (JBTS2) loci are allelic and caused by mutations in TMEM216, which encodes an uncharacterized tetraspan transmembrane protein. Individuals with CORS2 frequently had nephronophthisis and polydactyly, and two affected individuals conformed to the oro-facio-digital type VI phenotype, whereas skeletal dysplasia was common in fetuses affected by MKS. A single G218T mutation (R73L in the protein) was identified in all cases of Ashkenazi Jewish descent (n = 10). TMEM216 localized to the base of primary cilia, and loss of TMEM216 in mutant fibroblasts or after knockdown caused defective ciliogenesis and centrosomal docking, with concomitant hyperactivation of RhoA and Dishevelled. TMEM216 formed a complex with Meckelin, which is encoded by a gene also mutated in JSRDs and MKS. Disruption of tmem216 expression in zebrafish caused gastrulation defects similar to those in other ciliary morphants. These data implicate a new family of proteins in the ciliopathies and further support allelism between ciliopathy disorders.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U983, U781

Successful treatment of generalized pustular psoriasis with the interleukin-1-receptor antagonist anakinra: lack of correlation with IL1RN mutations

VIGUIER M, GUIGUE P, PAGES C, SMAHI A, BACHELEZ H

2010 - Ann. Intern. Med. 153(1):66-67

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

A new highly penetrant form of obesity due to deletions on chromosome 16p11.2

WALTERS RG, JACQUEMONT S, VALSESIA A, DE SMITH AJ, MARTINET D, ANDERSSON J, FALCHI M, CHEN F, ANDRIEUX J, LOBBENS S, DELOBEL B, STUTZMANN F, EL-SAYED MOUSTAFA JS, CHEVRE JC, LECOEUR C, VATIN V, BOUQUILLON S, BUXTON JL, BOUTE O, HOLDER-ESPINASSE M, CUISSET JM, LEMAITRE MP, AMBRESIN AE, BRIOSCHI A, GAILLARD M, GIUSTI V, FELLMANN F, FERRARINI A, HADJIKHANI N, CAMPION D, GUILMATRE A, GOLDENBERG A, CALMELS N, MANDEL JL, LE CAIGNEC C, DAVID A, ISIDOR B, CORDIER MP, DUPUIS-GIROD S, LABALME A, SANLAVILLE D, BERI-DEXHEIMER M, JONVEAUX P, LEHEUP B, OUNAP K, BOCHUKOVA EG, HENNING E, KEOGH J, ELLIS RJ, MACDERMOT KD, VAN HAELST MM, VINCENT-DELORME C, PLESSIS G, TOURAINE R, PHILIPPE A, MALAN V, MATHIEU-DRAMARD M, CHIESA J, BLAUMEISER B, KOOY RF, CAIAZZO R, PIGEYRE M, BALKAU B, SLADEK R, BERGMANN S, MOOSER V, WATERWORTH D, REYMOND A, VOLLENWEIDER P, WAEBER G, KURG A, PALTA P, ESKO T, METSPALU A, NELIS M, ELLIOTT P, HARTIKAINEN AL, MCCARTHY MI, PELTONEN L, CARLSSON L, JACOBSON P, SJOSTROM L, HUANG N, HURLES ME, O'RAHILLY S, FAROOQI IS, MANNIK K, JARVELIN MR, PATTOU F, MEYRE D, WALLEY AJ, COIN LJ, BLAKEMORE AI, FROGUEL P, BECKMANN JS

2010 - Nature 463(7281):671-5

Obesity has become a major worldwide challenge to public health, owing to an interaction between the Western 'obesogenic' environment and a strong genetic contribution. Recent extensive genome-wide association studies (GWASs) have identified numerous single nucleotide polymorphisms associated with obesity, but these loci together account for only a small fraction of the known heritable component. Thus, the 'common disease, common variant' hypothesis is increasingly coming under challenge. Here we report a highly penetrant form of obesity, initially observed in 31 subjects who were heterozygous for deletions of at least 593 kilobases at 16p11.2 and whose ascertainment included cognitive deficits. Nineteen similar deletions were identified from GWAS data in 16,053 individuals from eight European cohorts. These deletions were absent from healthy non-obese controls and accounted for 0.7% of our morbid obesity cases (body mass index (BMI) >/= 40 kg m(-2) or BMI standard deviation score >/= 4; P = 6.4 x 10(-8), odds ratio 43.0), demonstrating the potential importance in common disease of rare variants with strong effects. This highlights a promising strategy for identifying missing heritability in obesity and other complex traits: cohorts with extreme phenotypes are likely to be enriched for rare variants, thereby improving power for their discovery. Subsequent analysis of the loci so identified may well reveal additional rare variants that further contribute to the missing heritability, as recently reported for SIM1 (ref. 3). The most productive approach may therefore be to combine the 'power of the extreme' in small, well-phenotyped cohorts, with targeted follow-up in case-control and population cohorts.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Association of metalloproteinase gene polymorphisms with systemic sclerosis in the European caucasian population

WIPFF J, DIEUDE P, AVOUAC J, TIEV K, HACHULLA E, CRACOWSKI JL, DIOT E, SIBILIA J, MOUTHON L, MEYER O, KAHAN A, BOILEAU C, ALLANORE Y

2010 - J Rheumatol 37(3):599-602

OBJECTIVE: Systemic sclerosis (SSc) is classified among the complex genetic disorders and is characterized by massive extracellular matrix deposits. These may be due to overactivation of transforming growth factor ss that may be in part a result of abnormal remodeling of extracellular matrix and microfibrils. Metalloproteinases (MMP) are a family of proteolytic enzymes, and MMP 2, 9, and 14 contribute to the degradation of microfibrils. Our aim was to determine whether polymorphisms of the MMP2, MMP9, and MMP14 genes confer susceptibility to SSc in a large population. METHODS: A case-control study was performed in 659 SSc patients and 511 healthy matched controls from a European Caucasian population. Six Tag single-nucleotide polymorphisms (SNP) of the MMP2 gene and 2 SNP of MMP9 and MMP14 genes were genotyped. RESULTS: All SNP were in Hardy-Weinberg equilibrium in the control population. There was no association between the MMP2, MMP9, and MMP14 variants we investigated and SSc for allelic and genotype frequencies. No association was observed for the different subphenotypes of SSc patients. CONCLUSION: Our results in a large cohort of European Caucasian SSc patients do not support that MMP2, MMP9, and MMP14 genes are involved in the genetic background of SSc.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Mutations and polymorphisms in the proprotein convertase subtilisin kexin 9 (PCSK9) gene in cholesterol metabolism and disease

ABI-FADEL M, RABES JP, DEVILLERS M, MUNNICH A, ERLICH D, JUNIEN C, VARRET M, BOILEAU C

2009 - Hum Mutat 30(4):520-529

Hypercholesterolemia is one of the major causes of coronary heart disease (CHD). The genes encoding the low-density lipoprotein receptor and its ligand apolipoprotein B, have been the two genes classically implicated in autosomal dominant hypercholesterolemia (ADH). Our discovery in 2003 of the first mutations of the proprotein convertase subtilisin kexin 9 gene (PCSK9) causing ADH shed light on an unknown actor in cholesterol metabolism that since then has been extensively investigated. Several PCSK9 variants have been identified, some of them are gain-of-function mutations causing hypercholesterolemia by a reduction of low-density lipoprotein (LDL) receptor levels; while others are loss-of-function variants associated with a reduction of LDL-cholesterol (LDL-C) levels and a decreased risk of CHD. In this review, we focus on reported variants, and their biological, clinical, and functional relevance. We also highlight the spectrum of hypercholesterolemia or hypobetalipoproteinemia phenotypes that are already associated with mutations in PCSK9. Finally, we present future prospects concerning this therapeutic target that might constitute a new approach to reduce cholesterol levels and CHD, and enhance the effectiveness of other lipid-lowering drugs. Hum Mutat 0, 1-11, 2008. (c) 2008 Wiley-Liss, Inc.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

The molecular basis of familial hypercholesterolemia in Lebanon: spectrum of LDLR mutations and role of PCSK9 as a modifier gene

ABIFADEL M, RABES JP, JAMBART S, HALABY G, GANNAGE-YARED MH, SARKIS A, BEAINO G, VARRET M, SALEM N, CORBANI S, AYDENIAN H, JUNIEN C, MUNNICH A, BOILEAU C

2009 - Hum Mutat 30(7):E682-91

Autosomal dominant hypercholesterolemia (ADH), a major risk for coronary heart disease, is associated with mutations in the genes encoding the low-density lipoproteins receptor (LDLR), its ligand apolipoprotein B (APOB) or PCSK9 (Proprotein Convertase Subtilin Kexin 9). Familial hypercholesterolemia (FH) caused by mutation in the LDLR gene is the most frequent form of ADH. The incidence of FH is particularly high in the Lebanese population presumably as a result of a founder effect. In this study we characterize the spectrum of the mutations causing FH in Lebanon: we confirm the very high frequency of the LDLR p.Cys681X mutation that accounts for 81.5 % of the FH Lebanese probands recruited and identify other less frequent mutations in the LDLR. Finally, we show that the p.Leu21dup, an in frame insertion of one leucine to the stretch of 9 leucines in exon 1 of PCSK9, known to be associated with lower LDL-cholesterol levels in general populations, is also associated with a reduction of LDL-cholesterol levels in FH patients sharing the p.C681X mutation in the LDLR. Thus, by studying for the first time the impact of PCSK9 polymorphism on LDL-cholesterol levels of FH patients carrying a same LDLR mutation, we show that PCSK9 might constitute a modifier gene in familial hypercholesterolemia.

Unité(s) : U781, Centre de Génétique Médicale Jean Frézal

Pamidronate treatment of children with moderate-to-severe osteogenesis imperfecta: a note of caution

ALHARBI M, PINTO G, FINIDORI G, SOUBERBIELLE JC, GUILLOU F, GAUBICHER S, LE MERRER M, POLAK M

2009 - Horm. Res. 71(1):38-44

BACKGROUND/AIMS: Bisphosphonates have been reported to decrease fractures related to osteogenesis imperfecta (OI). We assessed the efficacy and long-term safety of pamidronate therapy in patients with moderate-to-severe OI. METHODS: We conducted an open-label uncontrolled study in 14 boys and 13 girls whose mean age was 6.8 years at baseline. Intravenous pamidronate, 1 mg/kg/day, was given for 3 consecutive days every 4 months for 2-6 years, with physical therapy and orthopedic surgery as appropriate. Mobility score, fracture rate, height, bone mineral density (BMD) and bone healing were evaluated throughout follow-up. RESULTS: In 24 (89%) patients, the fracture rate decreased to 6 months) occurred in 8 (29.6%) patients; their BMD gains, baseline age and treatment duration were not significantly different from those in the other patients. Tolerance was good. CONCLUSION: Pamidronate with physiotherapy and orthopedic management improved outcomes without delaying fracture healing in 19 (70%) of 27 patients. Delayed fracture healing occurred in 8/27 patients. Pamidronate should be reserved for severe OI with multiple fractures and/or flattened vertebras.

Unité(s) : Endocrinologie Pédiatrique et Gynécologie, Explorations Fonctionnelles, Centre de Génétique Médicale Jean Frézal, Traumatologie et Orthopédie Pédiatriques

PHOX2B in respiratory control: lessons from congenital central hypoventilation syndrome and its mouse models

AMIEL J, DUBREUIL V, RAMANANTSOA N, FORTIN G, GALLEGO J, BRUNET JF, GORIDIS C

2009 - Respir Physiol Neurobiol 168(1-2):125-32

Phox2b is a master regulator of visceral reflex circuits. Its role in the control of respiration has been highlighted by the identification of heterozygous PHOX2B mutations as the cause of Central Congenital Hypoventilation Syndrome (CCHS), a rare disease defined by the lack of CO(2) responsiveness and of breathing automaticity in sleep. Phox2b(27Ala/+) mice that bear a frequent CCHS-causing mutation do not respond to hypercapnia and die in the first hour after birth from central apnoea. They are therefore a reliable animal model for CCHS. Neurons of the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) were found severely depleted in these mice and no other neuronal loss could be identified. Physiological experiments show that RTN/pFRG neurons are crucial to driving proper breathing at birth and are necessary for central chemoreception and the generation of a normal respiratory rhythm. To date, the reason for the selective vulnerability of RTN/pFRG neurons to PHOX2B protein dysfunction remains unexplained.

Unité(s) : CENtre de Génétique Médicale Jean Frézal, U781

Genotype-phenotype correlation in four 15q24 deleted patients identified by array-CGH

ANDRIEUX J, DUBOURG C, RIO M, ATTIE-BITACH T, DELABY E, MATHIEU M, JOURNEL H, COPIN H, BLONDEEL E, DOCO-FENZY M, LANDAIS E, DELOBEL B, ODENT S, MANOUVRIER-HANU S, HOLDER-ESPINASSE M

2009 - Am J Med Genet A 149A(12):2813-9

Microdeletion 15q24 is an emerging syndrome recently described, mainly due to increased use of array-CGH. Clinical features associate mild to moderate developmental delay, typical facial characteristics (high forehead and frontal hairline, broad eyebrows, downslanting palpebral features, long philtrum), hands (particularly proximal implanted thumbs) and genital anomalies (micropenis, hypospadias). We report here on four de novo cases having 2.5-6.1 Mb deletions involving 15q24: one 15q23q24.2 (Patient 1) and three 15q24.1q24.2 deletions (Patients 2-4). We correlate phenotype to genotype according to molecular boundaries of these deletions. Since bilateral iris coloboma and severe ano-rectal malformation were only present in Patient 1, we could link these anomalies to haploinsufficiency of 15q23 genes. Neither hypospadias nor micropenis were present in Patient 3 bearing the smallest deletion, therefore we could define 500 kb 15q24.1 region linked to these anomalies.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Interaction between a chromosome 10 RET enhancer and chromosome 21 in the Down syndrome-Hirschsprung disease association

ARNOLD S, PELET A, AMIEL J, BORREGO S, HOFSTRA R, TAM P, CECCHERINI I, LYONNET S, SHERMAN S, CHAKRAVARTI A

2009 - Hum Mutat 30(5):771-5

Individuals with Down syndrome (DS) display a 40-fold greater risk of Hirschsprung disease (HSCR) than the general population of newborns implicating chromosome 21 in HSCR etiology. Here we demonstrate that the RET enhancer polymorphism RET+9.7 (rs2435357:C>T) at chromosome 10q11.2 is associated with HSCR in DS individuals both by transmission disequilibrium (P=0.0015) and case-control (P=0.0115) analysis of matched cases. Interestingly, the RET+9.7 T allele frequency is significantly different between individuals with DS alone (0.26+/-0.04), HSCR alone (0.61+/-0.04), and those with HSCR and DS (0.41+/-0.04), demonstrating an association and interaction between RET and chromosome 21 gene dosage. This is the first report of a genetic interaction between a common functional variant (rs2435357) and a not infrequent copy number error (chromosome 21 dosage) in two human developmental disorders.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Comparison of clinical presentations and outcomes between patients with TGFBR2 and FBN1 mutations in Marfan syndrome and related disorders

ATTIAS D, STHENEUR C, ROY C, COLLOD-BEROUD G, DETAINT D, FAIVRE L, DELRUE MA, COHEN L, FRANCANNET C, BEROUD C, CLAUSTRES M, ISERIN F, KIEN PK, LACOMBE D, LE MERRER M, LYONNET S, ODENT S, PLAUCHU H, RIO M, ROSSI A, SIDI D, STEG PG, RAVAUD P, BOILEAU C, JONDEAU G

2009 - Circulation 120(25):2541-9

BACKGROUND: TGFBR2 mutations were recognized recently among patients with a Marfan-like phenotype. The associated clinical and prognostic spectra remain unclear. METHODS AND RESULTS: Clinical features and outcomes of 71 patients with a TGFBR2 mutation (TGFBR2 group) were compared with 50 age- and sex-matched unaffected family members (control subjects) and 243 patients harboring FBN1 mutations (FBN1 group). Aortic dilatation was present in a similar proportion of patients in both the TGFBR2 and FBN1 groups (78% versus 79%, respectively) but was highly variable. The incidence and average age for thoracic aortic surgery (31% versus 27% and 35+/-16 versus 39+/-13 years, respectively) and aortic dissection (14% versus 10% and 38+/-12 versus 39+/-9 years) were also similar in the 2 groups. Mitral valve involvement (myxomatous, prolapse, mitral regurgitation) was less frequent in the TGFBR2 than in the FBN1 group (all P<0.05). Aortic dilatation, dissection, or sudden death was the index event leading to genetic diagnosis in 65% of families with TGFBR2 mutations, versus 32% with FBN1 mutations (P=0.002). The rate of death was greater in TGFBR2 families before diagnosis but similar once the disease had been recognized. Most pregnancies were uneventful (without death or aortic dissection) in both TGFBR2 and FBN1 families (38 of 39 versus 213 of 217; P=1). Seven patients (10%) with a TGFBR2 mutation fulfilled international criteria for Marfan syndrome, 3 of whom presented with features specific for Loeys-Dietz syndrome. CONCLUSIONS: Clinical outcomes appear similar between treated patients with TGFBR2 mutations and individuals with FBN1 mutations. Prognosis depends on clinical disease expression and treatment rather than simply the presence of a TGFBR2 gene mutation.

Unité(s) : Cardiologie Pédiatrique, Centre de Génétique Médicale Jean Frézal, U781

Mutations in DDR2 gene cause SMED with short limbs and abnormal calcifications

BARGAL R, CORMIER-DAIRE V, BEN-NERIAH Z, LE MERRER M, SOSNA J, MELKI J, ZANGEN DH, SMITHSON SF, BOROCHOWITZ Z, BELOSTOTSKY R, RAAS-ROTHSCHILD A

2009 - Am J Hum Genet 84(1):80-4

The spondylo-meta-epiphyseal dysplasia [SMED] short limb-hand type [SMED-SL] is a rare autosomal-recessive disease, first reported by Borochowitz et al. in 1993.(1) Since then, 14 affected patients have been reported.(2-5) We diagnosed 6 patients from 5 different consanguineous Arab Muslim families from the Jerusalem area with SMED-SL. Additionally, we studied two patients from Algerian and Pakistani ancestry and the parents of the first Jewish patients reported.(1) Using a homozygosity mapping strategy, we located a candidate region on chromosome 1q23 spanning 2.4 Mb. The position of the Discoidin Domain Receptor 2 (DDR2) gene within the candidate region and the similarity of the ddr2 knockout mouse to the SMED patients' phenotype prompted us to study this gene(6). We identified three missense mutations c.2254 C > T [R752C], c. 2177 T > G [I726R], c.2138C > T [T713I] and one splice site mutation [IVS17+1g > a] in the conserved sequence encoding the tyrosine kinase domain of the DDR2 gene. The results of this study will permit an accurate early prenatal diagnosis and carrier screening for families at risk.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Preimplantation genetic diagnosis: state of the art

BASILLE C, FRYDMAN R, EL ALY A, HESTERS L, FANCHIN R, TACHDJIAN G, STEFFANN J, LELORC'H M, ACHOUR-FRYDMAN N

2009 - Eur J Obstet Gynecol Reprod Biol 145(1):9-13

Preimplantation genetic diagnosis (PGD) is used to analyze embryos genetically before their transfer into the uterus. It was developed first in England in 1990, as part of progress in reproductive medicine, genetic and molecular biology. PGD offers couples at risk the chance to have an unaffected child, without facing termination of pregnancy. Embryos are obtained by in vitro fertilization with intracytoplasmic sperm injection (ICSI), and are biopsied mostly on day 3; blastocyst biopsy is mentioned as a possible alternative. The genetic analysis is performed on one or two blastomeres, by fluorescent in situ hybridization (FISH) for cytogenetic diagnosis, or polymerase chain reaction (PCR) for molecular diagnosis. Genetic analysis of the first or second polar body can be used to study maternal genetic contribution. Only unaffected embryos are transferred into the uterus. To improve the accuracy of the diagnosis, new technologies are emerging, with comparative genomic hybridization (CGH) and microarrays. In Europe, depending on national regulations, PGD is either prohibited, or allowed, or practiced in the absence of recommendations. The indications are chromosomal abnormalities, X-linked diseases or single gene disorders. The number of disorders being tested increases. In Europe, data collection from the year 2004 reports that globally 69.6% of cycles lead to embryo transfer and implantation rate is 17%. European results from the year 2004 show a clinical pregnancy rate of 18% per oocyte retrieval and 25% per embryo transfer, leading to 528 babies born. The cohort studies concerning the paediatric follow-up of PGD babies show developmental outcomes similar to children conceived after IVF-ICSI. Recent advances include human leucocyte antigen (HLA) typing for PGD embryos, when an elder sibling is affected with a genetic disorder and needs stem cell transplantation. The HLA-matched offspring resulting can give cord blood at birth. Preimplantation genetic screening (PGS) consists in euploid embryo selection; it could be used for advanced maternal age, repeated implantation failure, single embryo transfer or idiopathic recurrent pregnancy loss. These applications are controversial. PGD for inherited cancer predispositions is discussed and social sexing remains prohibited in Europe. PGD requires a close collaboration between obstetricians, fertility specialists, IVF laboratory and human geneticists. It needs intensive effort, expensive techniques and is demanding for the patients, but it offers tremendous opportunity for couples whose previous child has exhibited genetic abnormalities. The debate on certain indications is ongoing.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Prenatal diagnosis of brachytelephalangic chondrodysplasia punctata: case report

BENAICHA A, DOMMERGUES M, JOUANNIC JM, JACQUETTE A, ALEXANDRE M, LE MERRER M, DUCOU-LE POINTE H, GAREL C

2009 - Ultrasound Obstet. Gynecol. 34(6):724-726

Brachytelephalangic chondrodysplasia punctata is a rare congenital skeletal dysplasia. Within the heterogeneous group of chondrodysplasia punctata, the brachytelephalangic type is noteworthy because it has a better prognosis than do the other types. We report a case of brachytelephalangic chondrodysplasia punctata diagnosed by ultrasound imaging at 30 weeks' gestation; it was associated with polyhydramnios and a normal cervical spinal canal. Imaging features are described and differential diagnosis with other forms of chondrodysplasia punctata is discussed.

Unité(s) : Centre de Génétique Médicale Jean Frézal

SOS1 and PTPN11 mutations in five cases of Noonan syndrome with multiple giant cell lesions

BENETEAU C, CAVE H, MONCLA A, DORISON N, MUNNICH A, VERLOES A, LEHEUP B

2009 - Eur J Hum Genet 17(10):1216-1221

We report five cases of multiple giant cell lesions in patients with typical Noonan syndrome. Such association has frequently been referred to as Noonan-like/multiple giant cell (NL/MGCL) syndrome before the molecular definition of Noonan syndrome. Two patients show mutations in PTPN11 (p.Tyr62Asp and p.Asn308Asp) and three in SOS1 (p.Arg552Ser and p.Arg552Thr). The latter are the first SOS1 mutations reported outside PTPN11 in NL/MGCL syndrome. MGCL lesions were observed in jaws ('cherubism') and joints ('pigmented villonodular synovitis'). We show through those patients that both types of MGCL are not PTPN11-specific, but rather represent a low penetrant (or perhaps overlooked) complication of the dysregulated RAS/MAPK signaling pathway. We recommend discarding NL/MGCL syndrome from the nosology, as this presentation is neither gene-nor allele-specific of Noonan syndrome; these patients should be described as Noonan syndrome with MGCL (of the mandible, the long bone...). The term cherubism should be used only when multiple giant cell lesions occur without any other clinical and molecular evidence of Noonan syndrome, with or without mutations of the SH3BP2 gene.European Journal of Human Genetics advance online publication, 8 April 2009; doi:10.1038/ejhg.2009.44.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Highly conserved non-coding elements on either side of SOX9 associated with Pierre Robin sequence

BENKO S, FANTES JA, AMIEL J, KLEINJAN DJ, THOMAS S, RAMSAY J, JAMSHIDI N, ESSAFI A, HEANEY S, GORDON CT, MCBRIDE D, GOLZIO C, FISHER M, PERRY P, ABADIE V, AYUSO C, HOLDER-ESPINASSE M, KILPATRICK N, LEES MM, PICARD A, TEMPLE IK, THOMAS P, VAZQUEZ MP, VEKEMANS M, CROLLIUS HR, HASTIE ND, MUNNICH A, ETCHEVERS HC, PELET A, FARLIE PG, FITZPATRICK DR, LYONNET S

2009 - Nat Genet 41(3):359-64

Pierre Robin sequence (PRS) is an important subgroup of cleft palate. We report several lines of evidence for the existence of a 17q24 locus underlying PRS, including linkage analysis results, a clustering of translocation breakpoints 1.06-1.23 Mb upstream of SOX9, and microdeletions both approximately 1.5 Mb centromeric and approximately 1.5 Mb telomeric of SOX9. We have also identified a heterozygous point mutation in an evolutionarily conserved region of DNA with in vitro and in vivo features of a developmental enhancer. This enhancer is centromeric to the breakpoint cluster and maps within one of the microdeletion regions. The mutation abrogates the in vitro enhancer function and alters binding of the transcription factor MSX1 as compared to the wild-type sequence. In the developing mouse mandible, the 3-Mb region bounded by the microdeletions shows a regionally specific chromatin decompaction in cells expressing Sox9. Some cases of PRS may thus result from developmental misexpression of SOX9 due to disruption of very-long-range cis-regulatory elements.

Unité(s) : Pédiatrie Générale, Centre de Génétique Médicale Jean Frézal, U781

Sporadic case of unusual facies, cerebral vascular anomalies and developmental delay

BERTOLI M, BODDAERT N, RAOUL O, AMIEL J, LYONNET S

2009 - Clin Dysmorphol 18(2):110-111

Unité(s) : Radiologie Pédiatrique, Centre de Génétique Médicale Jean Frézal, U781

MRI findings in 77 children with non-syndromic autistic disorder

BODDAERT N, ZILBOVICIUS M, PHILIPE A, ROBEL L, BOURGEOIS M, BARTHELEMY C, SEIDENWURM D, MERESSE I, LAURIER L, DESGUERRE I, BAHI-BUISSON N, BRUNELLE F, MUNNICH A, SAMSON Y, MOUREN MC, CHABANE N

2009 - PLoS ONE 4(2):e4415

BACKGROUND: The clinical relevance of MR scanning in children with autism is still an open question and must be considered in light of the evolution of this technology. MRI was judged to be of insufficient value to be included in the standard clinical evaluation of autism according to the guidelines of the American Academy of Neurology and Child Neurology Society in 2000. However, this statement was based on results obtained from small samples of patients and, more importantly, included mostly insufficient MRI sequences. Our main objective was to evaluate the prevalence of brain abnormalities in a large group of children with a non-syndromic autistic disorder (AD) using T1, T2 and FLAIR MRI sequences. METHODOLOGY: MRI inspection of 77 children and adolescents with non-syndromic AD (mean age 7.4+/-3.6) was performed. All met the DSM-IV and ADI -R criteria for autism. Based on recommended clinical and biological screenings, we excluded patients with infectious, metabolic or genetic diseases, seizures or any other neurological symptoms. Identical MRI inspections of 77 children (mean age 7.0+/-4.2) without AD, developmental or neurological disorders were also performed. All MRIs were acquired with a 1.5-T Signa GE (3-D T1-FSPGR, T2, FLAIR coronal and axial sequences). Two neuroradiologists independently inspected cortical and sub-cortical regions. MRIs were reported to be normal, abnormal or uninterpretable. PRINCIPAL FINDINGS: MRIs were judged as uninterpretable in 10% (8/77) of the cases. In 48% of the children (33/69 patients), abnormalities were reported. Three predominant abnormalities were observed, including white matter signal abnormalities (19/69), major dilated Virchow-Robin spaces (12/69) and temporal lobe abnormalities (20/69). In all, 52% of the MRIs were interpreted as normal (36/69 patients). CONCLUSIONS: An unexpectedly high rate of MRI abnormalities was found in the first large series of clinical MRI investigations in non-syndromic autism. These results could contribute to further etiopathogenetic research into autism.

Unité(s) : Neurologie, Pédo-Psychiatrie, Radiologie pédiatrique, Centre de Génétique Médicale Jean Frézal, U781

Loss-of-Function Mutation in the Dioxygenase-Encoding FTO Gene Causes Severe Growth Retardation and Multiple Malformations

BOISSEL S, REISH O, PROULX K, KAWAGOE-TAKAKI H, SEDGWICK B, YEO GS, MEYRE D, GOLZIO C, MOLINARI F, KADHOM N, ETCHEVERS HC, SAUDEK V, FAROOQI IS, FROGUEL P, LINDAHL T, O'RAHILLY S, MUNNICH A, COLLEAUX L

2009 - Am J Hum Genet 85(1):106-111

FTO is a nuclear protein belonging to the AlkB-related non-haem iron- and 2-oxoglutarate-dependent dioxygenase family. Although polymorphisms within the first intron of the FTO gene have been associated with obesity, the physiological role of FTO remains unknown. Here we show that a R316Q mutation, inactivating FTO enzymatic activity, is responsible for an autosomal-recessive lethal syndrome. Cultured skin fibroblasts from affected subjects showed impaired proliferation and accelerated senescence. These findings indicate that FTO is essential for normal development of the central nervous and cardiovascular systems in human and establish that a mutation in a human member of the AlkB-related dioxygenase family results in a severe polymalformation syndrome.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Cholinergic switch associated with morphological differentiation in neuroblastoma

BOURDEAUT F, JANOUEIX-LEROSEY I, LUCCHESI C, PARIS R, RIBEIRO A, DE PONTUAL L, AMIEL J, LYONNET S, PIERRON G, MICHON J, PEUCHMAUR M, DELATTRE O

2009 - J Pathol 219(4):463-72

The morphology of malignant cells distinguishes between undifferentiated, poorly differentiated and differentiating neuroblastomas and constitutes a strong prognostic factor. Spontaneous or treatment-induced maturation characterizes a subset of neuroblastomas. It constitutes the basis of retinoic acid treatment to improve survival in aggressive neuroblastomas. However, the molecular events that drive differentiation are poorly understood. In the present study we have investigated the relationships between gene expression profiles and differentiation criteria in stroma-poor neuroblastomas. This study included three undifferentiated (UN), 20 poorly differentiated (PDN) and 11 differentiating (DN) neuroblastomas. These groups could be clearly separated using unsupervised clustering methods, which further enabled a major classification impact of genes involved in neural development, differentiation and function to be identified. UNs are characterized by high ASCL1, high PHOX2B, low GATA2, low TH and low DBH expressions. Most PDNs harbour a clear adrenergic phenotype, even in the presence of missense PHOX2B mutations. Finally, all DN tumours demonstrate cholinergic features. Depending upon their association with adrenergic characteristics, this enables dual 'cholinergic/adrenergic' and 'fully cholinergic' neuroblastomas to be defined. This suggests that the cholinergic switch, a final specification process that occurs physiologically in a minority of sympathetic neurons, is a critical step of differentiation in some neuroblastic tumours. This switch is associated with a down regulation of DBH that is apparently not strictly dependent upon PHOX2B. Conversely, GATA2 and TFAP2B may play critical roles in maintaining adrenergic features in poorly differentiated tumours.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

[Steroid-resistant nephrotic syndrome: recent genetic aspects.]

BOYER O, MACHUCA E, ESQUIVEL E, ANTIGNAC C

2009 - Arch Pediatr 16(6):796-798

Unité(s) : Centre de Génétique Médicale Jean Frézal, U574, Néphrologie Pédiatrique

The first founder DGUOK mutation associated with hepatocerebral mitochondrial DNA depletion syndrome

BRAHIMI N, JAMBOU M, SARZI E, SERRE V, BODDAERT N, ROMANO S, DE LONLAY P, SLAMA A, MUNNICH A, ROTIG A, BONNEFONT JP, LEBRE AS

2009 - Mol Genet Metab 97(3):221-6

Deoxyguanosine kinase (dGK) deficiency is a frequent cause of mitochondrial DNA depletion associated with a hepatocerebral phenotype. In this study, we describe a new splice site mutation in the DGUOK gene and the clinical, radiologic, and genetic features of these DGUOK patients. This new DGUOK homozygous mutation (c.444-62C>A) was identified in three patients from two North-African consanguineous families with combined respiratory chain deficiencies and mitochondrial DNA depletion in the liver. Brain MRIs are normal in DGUOK patients in the literature. Interestingly, we found subtentorial abnormal myelination and moderate hyperintensity in the bilateral pallidi in our patients. This new mutation creates a cryptic splice site in intron 3 (in position -62) and is predicted to result in a larger protein with an in-frame insertion of 20 amino acids. In silico analysis of the putative impact of the insertion shows serious clashes in protein conformation: this insertion disrupts the alpha5 helix of the dGK kinase domain, rendering the protein unable to bind purine deoxyribonucleosides. In addition, a common haplotype that segregated with the disease in both families was detected by haplotype reconstruction with 10 markers (microsatellites and SNPs), which span 4.6Mb of DNA covering the DGUOK locus. In conclusion, we report a new DGUOK splice site mutation that provide insight into a critical protein domain (dGK kinase domain) and the first founder mutation in a North-African population.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Phenotypic spectrum of STRA6 mutations: from Matthew-Wood syndrome to non-lethal anophthalmia

CHASSAING N, GOLZIO C, ODENT S, LEQUEUX L, VIGOUROUX A, MARTINOVIC-BOURIEL J, TIZIANO FD, MASINI L, PIRO F, MARAGLIANO G, DELEZOIDE AL, ATTIE-BITACH T, MANOUVRIER-HANU S, ETCHEVERS HC, CALVAS P

2009 - Hum Mutat 30(5):E673-81

Matthew-Wood, Spear, PDAC or MCOPS9 syndrome are alternative names used to refer to combinations of microphthalmia/anophthalmia, malformative cardiac defects, pulmonary dysgenesis, and diaphragmatic hernia. Recently, mutations in STRA6, encoding a membrane receptor for vitamin A-bearing plasma retinol binding protein, have been identified in such patients. We performed STRA6 molecular analysis in three fetuses and one child diagnosed with Matthew-Wood syndrome and in three siblings where two adult living brothers are affected with combinations of clinical anophthalmia, tetralogy of Fallot, and mental retardation. Among these patients, six novel mutations were identified, bringing the current total of known STRA6 mutations to seventeen. We extensively reviewed clinical data pertaining to all twenty-one reported patients with STRA6 mutations (the seven of this report and fourteen described elsewhere) and discuss additional features that may be part of the syndrome. The clinical spectrum associated with STRA6 deficiency is even more variable than initially described.

Unité(s) : U781, Centre de Génétique Médicale Jean Frézal

Xq28 duplication presenting with intestinal and bladder dysfunction and a distinctive facial appearance

CLAYTON-SMITH J, WALTERS S, HOBSON E, BURKITT-WRIGHT E, SMITH R, TOUTAIN A, AMIEL J, LYONNET S, MANSOUR S, FITZPATRICK D, CICCONE R, RICCA I, ZUFFARDI O, DONNAI D

2009 - Eur J Hum Genet 17(4):434-43

Xq28 duplications encompassing MECP2 have been described in male patients with a severe neurodevelopmental disorder associated with hypotonia and spasticity, severe learning disability and recurrent pneumonia. We identified an Xq28 duplication in three families where several male patients had presented with intestinal pseudo-obstruction or bladder distension. The affected boys had similar dysmorphic facial appearances. Subsequently, we ascertained seven further families where the proband presented with similar features. We demonstrated duplications of the Xq28 region in five of these additional families. In addition to MECP2, these duplications encompassed several other genes already known to be associated with diseases including SLC6A8, L1CAM and Filamin A (FLNA). The two remaining families were shown to have intragenic duplications of FLNA only. We discuss which elements of the Xq28 duplication phenotype may be associated with the various genes in the duplication. We propose that duplication of FLNA may contribute to the bowel and bladder phenotype seen in these seven families.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Sleep-disordered breathing in children

COHEN-GOGO S, DO NGOC THANH C, LEVY D, METREAU J, MORNAND P, PARISOT P, FAUROUX B

2009 - Archives Pédiatrie 16(2):123-131

Sleep-disordered breathing (SDB) in children comprises a wide spectrum of symptoms ranging from primary snoring to obstructive sleep apnea (OSA). Twelve percent of children present primary snoring and 1-2% OSA. Polysomnography is the gold standard for diagnosis of SDB allowing the analysis of sleep stages, respiratory movements, airflow, and gas exchange. However, this test remains highly technical, expensive, and difficult to conduct; other simpler diagnostic methods are under evaluation. Recent studies highlight the frequency and importance of cognitive and behavioral disorders in children with SDB; both the age and the severity of the SDB seem to modulate in the expression of neurocognitive consequences. Local and systemic inflammation plays a key role in the physiopathology of SDB and its complications: OSA is a cardiovascular risk factor in childhood that could favor atheromatous complications later in life. Adenoidotonsillectomy is the treatment of choice, but anti-inflammatory therapies such as leukotriene receptor antagonists or nasal corticoids may be beneficial in mild SDB or in residual OSA after adenotonsillectomy. In case of failure, noninvasive ventilation by means of nasal continuous positive pressure will be necessary, aided by specialists. SDB and OSA are a public health problem, underlining the pivotal role of the pediatrician in preventing, diagnosing, and treating these frequent disorders.

Unité(s) : Cardiologie Pédiatrique, Centre de Génétique Médicale Jean Frézal

WNT/beta-catenin pathway activation in Wilms tumors: A unifying mechanism with multiple entries?

CORBIN M, DE REYNIES A, RICKMAN DS, BERREBI D, BOCCON-GIBOD L, COHEN-GOGO S, FABRE M, JAUBERT F, FAUSSILLON M, YILMAZ F, SARNACKI S, LANDMAN-PARKER J, PATTE C, SCHLEIERMACHER G, ANTIGNAC C, JEANPIERRE C

2009 - Genes Chromosomes Cancer 48(9):816-827

Based on characterization of both genomic and expression status of WT1 and CTNNB1 (beta-catenin) in a series of 60 Wilms tumor samples, combined with genome-wide expression profiling of these tumors, normal mature and fetal kidney controls, we show that WT1/beta-catenin expression was a better classifier than WT1/CTNNB1 mutations. We present molecular data supporting that the WNT pathway is involved in both tumor classes, with and without WT1/beta-catenin alterations. In the tumor class with WT1/beta-catenin alterations, we identified overexpression of 14 previously unreported WNT target genes, including TWIST1. We show that the TWIST1 protein was specifically expressed in these tumors, where staining was restricted to the stromal, nuclear beta-catenin positive, component. By comparing the state of the WNT pathway in tumors without WT1/beta-catenin alterations and fetal kidneys we provide evidence that suggests that these tumors have a heightened level of pathway activation. We characterized mutations of the WNT pathway regulator gene WTX in 16% of this tumor class. Moreover, genome-transcriptome correlation analysis allowed us to identify three other WNT pathway regulator genes that could participate in the activation of the WNT pathway: BCL9 (1p36.2), CTNNBIP1 (1p36.2), and CBY1 (22q13.1). These genes thus represent new potential important actors in WT tumorigenesis. (c) 2009 Wiley-Liss, Inc.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Anatomie Pathologique, Chirurgie Viscérale Pédiatrique, U574, U781

Abnormal oral-pharyngeal swallowing as cause of morbidity and early death in Stuve-Wiedemann syndrome

CORONA-RIVERA JR, CORMIER-DAIRE V, DAGONEAU N, COELLO-RAMIREZ P, LOPEZ-MARURE E, ROMO-HUERTA CO, SILVA-BAEZ H, AGUIRRE-SALAS LM, ESTRADA-SOLORIO MI

2009 - Eur J Med Genet 52(4):242-6

Stuve-Wiedemann syndrome (SWS) is an autosomal recessive bone dysplasia (OMIM #601559) characterized by bowing of long bones, camptodactyly, respiratory insufficiency, hyperthermic episodes, and neonatal death from hyperthermia or apnea. We describe two female siblings with SWS born from consanguineous Gypsy parents. For a further delineation of SWS, we report hypothyroidism and ectopic thyroid as part of its phenotypic spectrum. Molecular study in the leukemia inhibitory factor receptor (LIFR) gene (OMIM *151 443) demonstrated the presence of a mutation. We observed that in one of our patients, oropharyngeal disruption in the swallowing process caused repetitive aspiration pneumonias, life-threatening events, and finally death. We emphasize that these features represent dysautonomic manifestations of SWS, and are probably related to pharyngoesophageal dyskinesia due to abnormal autonomic control of the anterior rami of cervical roots C1-C5.

Unité(s) : U781, Centre de Génétique Médicale Jean Frézal

DYNC2H1 mutations cause asphyxiating thoracic dystrophy and short rib-polydactyly syndrome, type III

DAGONEAU N, GOULET M, GENEVIEVE D, SZNAJER Y, MARTINOVIC J, SMITHSON S, HUBER C, BAUJAT G, FLORI E, TECCO L, CAVALCANTI D, DELEZOIDE AL, SERRE V, LE MERRER M, MUNNICH A, CORMIER-DAIRE V

2009 - Am J Hum Genet 84(5):706-11

Jeune asphyxiating thoracic dystrophy (ATD) is an autosomal-recessive chondrodysplasia characterized by short ribs and a narrow thorax, short long bones, inconstant polydactyly, and trident acetabular roof. ATD is closely related to the short rib polydactyly syndrome (SRP) type III, which is a more severe condition characterized by early prenatal expression and lethality and variable malformations. We first excluded IFT80 in a series of 26 fetuses and children belonging to 14 families diagnosed with either ATD or SRP type III. Studying a consanguineous family from Morocco, we mapped an ATD gene to chromosome 11q14.3-q23.1 in a 20.4 Mb region and identified homozygous mutations in the cytoplasmic dynein 2 heavy chain 1 (DYNC2H1) gene in the affected children. Compound heterozygosity for DYNC2H1 mutations was also identified in four additional families. Among the five families, 3/5 were diagnosed with ATD and 2/5 included pregnancies terminated for SRP type III. DYNC2H1 is a component of a cytoplasmic dynein complex and is directly involved in the generation and maintenance of cilia. From this study, we conclude that ATD and SRP type III are variants of a single disorder belonging to the ciliopathy group.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Contribution of three-dimensional computed tomography in prenatal diagnosis of lethal infantile cortical hyperostosis (Caffey disease)

DARMENCY V, THAUVIN-ROBINET C, ROUSSEAU T, MEJEAN N, CHARRA S, CORON F, CASSINI C, HUET F, LE MERRER M, CORMIER-DAIRE V, LAURENT N, SAGOT P, FAIVRE L

2009 - Prenat Diagn 29(9):892-4

Unité(s) : Centre de Génétique Médicale Jean Frézal

Novel B3GALTL mutation in Peters-plus Syndrome

DASSIE-AJDID J, CAUSSE A, POIDVIN A, GRANIER M, KAPLAN J, BURGLEN L, DOUMMAR D, TEISSEIRE P, VIGOUROUX A, MALECAZE F, CALVAS P, CHASSAING N

2009 - Clin Genet 76(5):490-2

Unité(s) : Centre de Génétique Médicale Jean Frézal

Mutational, functional, and expression studies of the TCF4 gene in Pitt-Hopkins syndrome

DE PONTUAL L, MATHIEU Y, GOLZIO C, RIO M, MALAN V, BODDAERT N, SOUFFLET C, PICARD C, DURANDY A, DOBBIE A, HERON D, ISIDOR B, MOTTE J, NEWBURRY-ECOB R, PASQUIER L, TARDIEU M, VIOT G, JAUBERT F, MUNNICH A, COLLEAUX L, VEKEMANS M, ETCHEVERS H, LYONNET S, AMIEL J

2009 - Hum Mutat 30(4):669-76

Pitt-Hopkins syndrome is a severe congenital encephalopathy recently ascribed to de novo heterozygous TCF4 gene mutations. We report a series of 13 novel PHS cases with a TCF4 mutation and show that EEG, brain magnetic resonance imagain (MRI), and immunological investigations provide valuable additional clues to the diagnosis. We confirm a mutational hot spot in the basic domain of the E-protein. Functional studies illustrate that heterodimerisation of mutant TCF4 proteins with a tissue-specific transcription factor is less effective than that homodimerisation in a luciferase reporter assay. We also show that the TCF4 expression pattern in human embryonic development is widespread but not ubiquitous. In summary, we further delineate an underdiagnosed mental retardation syndrome, highlighting TCF4 function during development and facilitating diagnosis within the first year of life.

Unité(s) : Anatomie Pathologique, Radiologie Pédiatrique, Centre de Génétique Médicale Jean Frézal, U663, U768, U781

Epistasis between RET and BBS mutations modulates enteric innervation and causes syndromic Hirschsprung disease

DE PONTUAL L, ZAGHLOUL NA, THOMAS S, DAVIS EE, MCGAUGHEY DM, DOLLFUS H, BAUMANN C, BESSLING SL, BABARIT C, PELET A, GASCUE C, BEALES P, MUNNICH A, LYONNET S, ETCHEVERS H, ATTIE-BITACH T, BADANO JL, MCCALLION AS, KATSANIS N, AMIEL J

2009 - Proc Natl Acad Sci U S A 106(33):13921-13926

Hirschsprung disease (HSCR) is a common, multigenic neurocristopathy characterized by incomplete innervation along a variable length of the gut. The pivotal gene in isolated HSCR cases, either sporadic or familial, is RET. HSCR also presents in various syndromes, including Shah-Waardenburg syndrome (WS), Down (DS), and Bardet-Biedl (BBS). Here, we report 3 families with BBS and HSCR with concomitant mutations in BBS genes and regulatory RET elements, whose functionality is tested in physiologically relevant assays. Our data suggest that BBS mutations can potentiate HSCR predisposing RET alleles, which by themselves are insufficient to cause disease. We also demonstrate that these genes interact genetically in vivo to modulate gut innervation, and that this interaction likely occurs through complementary, yet independent, pathways that converge on the same biological process.

Unité(s) : U781, Centre de Génétique Médicale Jean Frézal

Nephrocystin-1 and nephrocystin-4 are required for epithelial morphogenesis and associate with PALS1/PATJ and Par6

DELOUS M, HELLMAN NE, GAUDE HM, SILBERMANN F, LE BIVIC A, SALOMON R, ANTIGNAC C, SAUNIER S

2009 - Hum Mol Genet 18(24):4711-23

Nephronophthisis is an autosomal recessive disorder characterized by renal fibrosis, tubular basement membrane disruption and corticomedullary cyst formation leading to end-stage renal failure. The disease is caused by mutations in NPHP1-9 genes, which encode the nephrocystins, proteins localized to cell-cell junctions and centrosome/primary cilia. Here, we show that nephrocystin mRNA expression is dramatically increased during cell polarization, and shRNA-mediated knockdown of either NPHP1 or NPHP4 in MDCK cells resulted in delayed tight junction formation, abnormal cilia formation, and disorganized multi-lumen structures when grown in a three-dimensional collagen matrix. Some of these phenotypes are similar to those reported for cells depleted of the tight junction proteins PALS1 or Par3, and interestingly, we demonstrate a physical interaction between these nephrocystins and PALS1 as well as their partners PATJ and Par6, and show their partial colocalization in human renal tubules. Taken together, these results demonstrate that the nephrocystins play an essential role in epithelial cell organization, suggesting a plausible mechanism by which the in vivo histopathologic features of nephronophthisis might develop.

Unité(s) : U574, Centre de Génétique Médicale Jean Frézal, Néphrologie Pédiatrique

First fixed drug eruption due to teicoplanin with a peri-oral distribution

DUONG T, HAMEL D, BENLAHRECH S, LE-QUAN-SANG KH, SAUVE-MARTIN H, DE PROST Y, ROUJEAU JC, HADJ-RABIA S

2009 - J Eur Acad Dermatol Venereol 23(9):1107

Unité(s) : Centre de Génétique Médicale Jean Frézal, Dermatologie

Molecular screening of 980 cases of suspected hereditary optic neuropathy with a report on 77 novel OPA1 mutations

FERRE M, BONNEAU D, MILEA D, CHEVROLLIER A, VERNY C, DOLLFUS H, AYUSO C, DEFOORT S, VIGNAL C, ZANLONGHI X, CHARLIN JF, KAPLAN J, ODENT S, HAMEL CP, PROCACCIO V, REYNIER P, AMATI-BONNEAU P

2009 - Hum Mutat 30(7):E692-705

We report the results of molecular screening in 980 patients carried out as part of their work-up for suspected hereditary optic neuropathies. All the patients were investigated for Leber's hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (ADOA), by searching for the ten primary LHON-causing mtDNA mutations and examining the entire coding sequences of the OPA1 and OPA3 genes, the two genes currently identified in ADOA. Molecular defects were identified in 440 patients (45% of screened patients). Among these, 295 patients (67%) had an OPA1 mutation, 131 patients (30%) had an mtDNA mutation, and 14 patients (3%), belonging to three unrelated families, had an OPA3 mutation. Interestingly, OPA1 mutations were found in 157 (40%) of the 392 apparently sporadic cases of optic atrophy. The eOPA1 locus-specific database now contains a total of 204 OPA1 mutations, including 77 novel OPA1 mutations reported here. The statistical analysis of this large set of mutations has led us to propose a diagnostic strategy that should help with the molecular work-up of optic neuropathies. Our results highlight the importance of investigating LHON-causing mtDNA mutations as well as OPA1 and OPA3 mutations in cases of suspected hereditary optic neuropathy, even in absence of a family history of the disease.

Unité(s) : U781, Centre de Génétique Médicale Jean Frézal

Glutathione S-transferases related to P. aeruginosa lung infection in cystic fibrosis children: Preliminary study

FEUILLET-FIEUX MN, NGUYEN-KHOA T, LORIOT MA, KELLY M, DE VILLARTAY JP, SERMET-GAUDELUS I, VERRIER P, BONNEFONT JP, BEAUNE P, LENOIR G, LACOUR B

2009 - Clin. Biochem. 42(1-2):57-63

OBJECTIVES: In cystic fibrosis (CF) children, we investigated the predictive impact of glutathione S-transferases (GST) activity and genotypes P1, M1 and T1, and antioxidant levels on stage-severity of Pseudomonas aeruginosa lung infection. METHODS: GST activity was determined in whole blood by spectrophotometry, and GST genotypes by multiplex PCR RFLP for 36 CF and 9 control children. Levels of glutathione in erythrocyte and vitamins A, E and C in plasma were measured by HPLC. RESULTS: No difference in GST activity and no relationship between GST activity and antioxidant levels were observed in CF children as compared to controls. However, GST activity was lower in CF children with severe clinical status and infection, and the frequency of GSTP1 wild type genotype AA, prevalent in uninfected CF children (75%), decreased in infected ones (33%). CONCLUSION: GST activity and genotype could play an important role in modulating P. aeruginosa lung infection in CF patients.

Unité(s) : Biochimie Générale, Département de Pédiatrie, Génétique Médicale Pédiatrique

Sexual dimorphism in environmental epigenetic programming

GABORY A, ATTIG L, JUNIEN C

2009 - Mol Cell Endocrinol 304(1-2):8-18

The phenotype of an individual is the result of complex interactions between genotype and current, past and ancestral environment leading to a lifelong remodelling of our epigenomes. The vast majority of common diseases, including atherosclerosis, diabetes, osteoporosis, asthma, neuropsychological and autoimmune diseases, which often take root in early development, display some degree of sex bias, very marked in some cases. This bias could be explained by the role of sex chromosomes, the different regulatory pathways underlying sexual development of most organs and finally, lifelong fluctuating impact of sex hormones. A substantial proportion of dimorphic genes expression might be under the control of sex-specific epigenetic marks. Environmental factors such as social behaviour, nutrition or chemical compounds can influence, in a gender-related manner, these flexible epigenetic marks during particular spatiotemporal windows of life. Thus, finely tuned developmental program aspects, for each sex, may be more sensitive to specific environmental challenges, particularly during developmental programming and gametogenesis, but also throughout the individual's life under the influence of sex steroid hormones and/or sex chromosomes. An unfavourable programming could thus lead to various defects and different susceptibility to diseases between males and females. Recent studies suggest that this epigenetic programming could be sometimes transmitted to subsequent generations in a sex-specific manner and lead to transgenerational effects (TGEs). This review summarizes the current understanding in the field of epigenetic programming and highlights the importance of studying both sexes in epidemiological protocols or dietary interventions both in humans and in experimental animal models.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Hypertelorism-microtia-clefting syndrome (HMC syndrome): prenatal diagnosis in two siblings

GHOUMID J, ANSART-FRANQUET H, SUBTIL D, PASZ N, DEVISME L, AMIEL J, ANDRIEUX J, MANOUVRIER-HANU S, HOLDER-ESPINASSE M

2009 - Prenat Diagn 29(11):1064-5

Unité(s) : Centre de Génétique Médicale Jean Frézal

Misleading behavioural phenotype with adenylosuccinate lyase deficiency

GITIAUX C, CEBALLOS-PICOT I, MARIE S, VALAYANNOPOULOS V, RIO M, VERRIERES S, BENOIST JF, VINCENT MF, DESGUERRE I, BAHI-BUISSON N

2009 - Eur. J. Human Genet. 17(1):133-136

Adenylosuccinate lyase deficiency is a rare autosomal disorder of de novo purine synthesis, which results in the accumulation of succinylpurines in body fluids. Patients with adenylosuccinate lyase deficiency show a variable combination of mental retardation, epilepsy and autistic features and are usually discovered during screens for unexplained encephalopathy using the Bratton-Marshall assay that reveals the excretion of the succinylaminoimidazolecarboxamide riboside (SAICAr). Here, we report on two sisters aged 11 and 12 years presented with global developmental delay, motor apraxia, severe speech deficits, seizures and behavioural features, which combined excessive laughter, a very happy disposition, hyperactivity, a short attention span, the mouthing of objects, tantrums and stereotyped movements that gave a behavioural profile mimicking Angelman syndrome. Both patients had an increased succinyladenosine/SAICAr ratio of 1.6, and exhibited a novel homozygous missense mutation (c.674T>C; p.Met225Thr) in the exon 6 of the ADSL gene. We suggest that these clinical features might be a new presentation of adenylosuccinate lyase deficiency. On the basis of this observation, although adenylosuccinate lyase deficiency is a rare disorder, this diagnosis should be considered in patients with mental retardation and a behavioural profile suggestive of Angelman syndrome.European Journal of Human Genetics advance online publication, 1 October 2008; doi:10.1038/ejhg.2008.174.

Unité(s) : Biochimie Métabolique, Génétique Médicale Pédiatrique, Métabolisme, Neurologie

Genetic and molecular aspects of acromelic dysplasia

GOFF CL, CORMIER-DAIRE V

2009 - Pediatr Endocrinol Rev 6(3):418-23

The acromelic dysplasia group includes three rare disorders: Weill-Marchesani syndrome (WMS), Geleophysic dysplasia (GD) and Acromicric dysplasia (AD) all characterized by short stature, short hands and stiff joints. The clinical overlap between the three disorders is striking. Indeed, in addition to the diagnostic criteria, they all share common features including delayed bone age, cone shaped epiphyses, thick skin and heart disease. In contrast, a microspherophakic lens seems to be a characteristic feature of WMS whereas hepatomegaly and a severe outcome are encountered only in the most severe forms of GD. Finally, WMS is transmitted either by an autosomal dominant or an autosomal recessive (AR) mode of inheritance, GD by an autosomal recessive mode of inheritance and AD by an autosomal dominant mode of inheritance. Using genetic approaches, we have identified the molecular basis of WMS and GD which both involved the same superfamily of proteins, the ADAMTS [A Disintegrin-like And Metalloproteinase domain (reprolysin type) with ThromboSpondin type 1 repeats (TSR)]. We have found ADAMTS10 mutations in the recessive form of WMS and Fibrillin 1 mutations in the dominant form of WMS. More recently, we have identified ADAMTSL2 mutations in GD. The function of ADAMTS1 0 and AD AMTSL 2 are unknown. But the findings of FBN1 and ADAMTS10 mutations in WMS suggest a direct link between the two proteins. Using a yeast double hybrid screen, we have identified LTBP1 (Latent TGFbeta Binding protein 1) as a partner of ADAMTSL2. The combination of these findings suggests that ADAMTS10 and ADAMTSL2 are both involved in the microfibrillar network.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Long-range regulation at the SOX9 locus in development and disease

GORDON CT, TAN TY, BENKO S, FITZPATRICK D, LYONNET S, FARLIE PG

2009 - J Med Genet 46(10):649-56

The involvement of SOX9 in congenital skeletal malformation was demonstrated 15 years ago with the identification of mutations in and around the gene in patients with campomelic dysplasia (CD). Translocations upstream of the coding sequence suggested that altered expression of SOX9 was capable of severely impacting on skeletal development. Subsequent studies in humans and animal models pointed towards a complex regulatory region controlling SOX9 transcription, involving approximately 1 Mb of upstream sequence. Recent data indicate that this regulatory domain may extend substantially further, with identification of several disruptions greater than 1 Mb upstream of SOX9 associated with isolated Pierre Robin sequence (PRS), a craniofacial disorder that is frequently a component of CD. The translocation breakpoints upstream of SOX9 can now be clustered into three groups, with a trend towards less severe skeletal phenotypes as the distance of each cluster from SOX9 increases. In this review we discuss how the identification of novel lesions surrounding SOX9 support the existence of tissue specific enhancers acting over a large distance to regulate expression of the gene during craniofacial development, and we highlight the potential for discovery of additional regulatory elements within the extended SOX9 control region.

Unité(s) : U781, Centre de Génétique Médicale Jean Frézal

Mutations des genes du SRA et anomalies du developpement renal

GUBLER MC, GRIBOUVAL O, MORINIERE V, PAWTOWSKI A, ANTIGNAC C

2009 - J Soc Biol 203(4):311-318

La dysgenesie tubulaire renale (DTR) autosomique recessive est une anomalie severe du developpement renal. Elle se manifeste par une anurie foetale persistante responsable d'oligoamnios et, le plus souvent, de mort perinatale. Il s'y associe une hypotension refractaire observee chez les nouveau-nes survivants et un retard d'ossification de la voute cranienne. La nephropathie est caracterisee histologiquement par l'absence, ou la presence d'un nombre tres reduit de tubes proximaux differencies, associees constamment a une anomalie majeure de l'expression renale de renine. Nous avons recemment montre que cette nephropathie etait liee a des mutations des genes codant pour les differentes proteines du systeme renine-angiotensine (SRA). L'etude de 46 familles confirme le role majeur des mutations des genes du SRA a l'origine de la DTR recessive autosomique : des mutations homozygotes ou heterozygotes composites ont ete identifiees dans 41 familles (F). Elles touchaient les genes REN (9F), AGT (3F), AGTR1 (3F) ou ACE (26F). Le phenotype est le meme quel que soit le gene mute. Les parents sont asymptomatiques. Cette etude souligne l'importance du SRA dans le developpement du rein humain. L'identification du defaut moleculaire permet de proposer a la famille un conseil genetique precis et a leur demande un diagnostic prenatal precoce.

Unité(s) : U574, Centre de Génétique Médicale Jean Frézal, Néphrologie Pédiatrique

Giant diencephalic harmartoma and related anomalies: a newly recognized entity distinct from the Pallister-Hall syndrome

GUIMIOT F, MARCORELLES P, ABOURA A, BONYHAY G, PATRIER S, MENEZ F, DROUIN-GARRAUD V, ICOWICK V, EURIN D, GAREL C, MOIROT H, VERSPYCK E, SAUGIER-VEBER P, ATTIE-BITACH T, PICONE O, OURY JF, VERLOES A, DELEZOIDE AL, LAQUERRIERE PA

2009 - Am J Med Genet A 149A(6):1108-15

An hypothalamic hamartoma is an abnormal mass of mature glio-neuronal tissue present in the hypothalamic area. It usually measures <2 cm of diameter. Most of the time, this hamartoma occurs in Pallister-Hall syndrome (PHS), due to heterozygous GLI3 mutations. We report on five fetuses with giant diencephalic hamartoma and other midline brain and facial malformations, without mutation in the GLI3 gene or genomic rearrangements in three of them. The fetuses showed facial asymmetry, unilateral ear and eye anomalies, and facial cleft. Extracephalic malformations consisted of vertebral anomalies and short nails, without polydactyly and cardiac malformation. The diencephalon was replaced by an encephaloid mass protruding into the facial cleft. Normal cerebral structures were not detectable. In one patient, holoprosencephaly of the syntelencephalic type was noted. Arhinencephaly was present in all patients. Histologically, the ill-defined, multilobulated lesion was made of neuroblastic and neurocytic cell foci, lying in a fibrillar network, elaborating sometimes perivascular pseudorosettes, with a maturation gradient in accordance with the fetal age. Owing to their location, the tumors could be described as diencephalic, rather than hypothalamic hamartomas. The striking asymmetry of the facial anomalies and the diencephalic malformations are not in the spectrum observed with PHS and related syndromes, suggesting a distinct entity involving abnormal morphogenetic developmental fields at around 5 weeks of gestation.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

TMEM126A, Encoding a Mitochondrial Protein, Is Mutated in Autosomal-Recessive Nonsyndromic Optic Atrophy

HANEIN S, PERRAULT I, ROCHE O, GERBER S, KHADOM N, RIO M, BODDAERT N, JEAN-PIERRE M, BRAHIMI N, SERRE V, CHRETIEN D, DELPHIN N, FARES-TAIE L, LACHHEB S, ROTIG A, MEIRE F, MUNNICH A, DUFIER JL, KAPLAN J, ROZET JM

2009 - Am J Hum Genet 84(4):493-498

Nonsyndromic autosomal-recessive optic neuropathies are rare conditions of unknown genetic and molecular origin. Using an approach of whole-genome homozygosity mapping and positional cloning, we have identified the first gene, to our knowledge, responsible for this condition, TMEM126A, in a large multiplex inbred Algerian family and subsequently in three other families originating from the Maghreb. TMEM126A is conserved in higher eukaryotes and encodes a transmembrane mitochondrial protein of unknown function, supporting the view that mitochondrial dysfunction may be a hallmark of inherited optic neuropathies including isolated autosomal-recessive forms.

Unité(s) : Ophtalmologie, Radiologie Pédiatrique, Centre de Génétique Médicale Jean Frézal, U781

Elements of morphology: standard terminology for the nose and philtrum

HENNEKAM RC, CORMIER-DAIRE V, HALL JG, MEHES K, PATTON M, STEVENSON RE

2009 - Am J Med Genet A 149A(1):61-76

An international group of clinicians working in the field of dysmorphology has initiated the standardization of terms used to describe human morphology. The goals are to standardize these terms and reach consensus regarding their definitions. In this way, we will increase the utility of descriptions of the human phenotype and facilitate reliable comparisons of findings among patients. Discussions with other workers in dysmorphology and related fields, such as developmental biology and molecular genetics, will become more precise. Here we introduce the anatomy of the nose and philtrum, and define and illustrate the terms that describe the major characteristics of these body regions.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

A large-scale mutation search reveals genetic heterogeneity in 3M syndrome

HUBER C, DELEZOIDE AL, GUIMIOT F, BAUMANN C, MALAN V, LE MERRER M, DA SILVA DB, BONNEAU D, CHATELAIN P, CHU C, CLARK R, COX H, EDERY P, EDOUARD T, FANO V, GIBSON K, GILLESSEN-KAESBACH G, GIOVANNUCCI-UZIELLI ML, GRAUL-NEUMANN LM, VAN HAGEN JM, VAN HEST L, HOROVITZ D, MELKI J, PARTSCH CJ, PLAUCHU H, RAJAB A, ROSSI M, SILLENCE D, STEICHEN-GERSDORF E, STEWART H, UNGER S, ZENKER M, MUNNICH A, CORMIER-DAIRE V

2009 - Eur J Hum Genet 17(3):395-400

The 3M syndrome is a rare autosomal recessive disorder recently ascribed to mutations in the CUL7 gene and characterized by severe pre- and postnatal growth retardation. Studying a series of 33 novel cases of 3M syndrome, we have identified deleterious CUL7 mutations in 23/33 patients, including 19 novel mutations and one paternal isodisomy of chromosome 6 encompassing a CUL7 mutation. Lack of mutations in 10/33 cases and exclusion of the CUL7 locus on chromosome 6p21.1 in six consanguineous families strongly support the genetic heterogeneity of the 3M syndrome.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Identification of CANT1 Mutations in Desbuquois Dysplasia

HUBER C, OULES B, BERTOLI M, CHAMI M, FRADIN M, ALANAY Y, AL-GAZALI LI, AUSEMS MG, BITOUN P, CAVALCANTI DP, KREBS A, LE MERRER M, MORTIER G, SHAFEGHATI Y, SUPERTI-FURGA A, ROBERTSON SP, LE GOFF C, MUDA AO, PATERLINI-BRECHOT P, MUNNICH A, CORMIER-DAIRE V

2009 - Am J Hum Genet 85(5):706-710

Desbuquois dysplasia is a severe condition characterized by short stature, joint laxity, scoliosis, and advanced carpal ossification with a delta phalanx. Studying nine Desbuquois families, we identified seven distinct mutations in the Calcium-Activated Nucleotidase 1 gene (CANT1), which encodes a soluble UDP-preferring nucleotidase belonging to the apyrase family. Among the seven mutations, four were nonsense mutations (Del 5' UTR and exon 1, p.P245RfsX3, p.S303AfsX20, and p.W125X), and three were missense mutations (p.R300C, p.R300H, and p.P299L) responsible for the change of conserved amino acids located in the seventh nucleotidase conserved region (NRC). The arginine substitution at position 300 was identified in five out of nine families. The specific function of CANT1 is as yet unknown, but its substrates are involved in several major signaling functions, including Ca(2+) release, through activation of pyrimidinergic signaling. Importantly, using RT-PCR analysis, we observed a specific expression in chondrocytes. We also found electron-dense material within distended rough endoplasmic reticulum in the fibroblasts of Desbuquois patients. Our findings demonstrate the specific involvement of a nucleotidase in the endochondral ossification process.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781, U807

Congenital skin pedicles with or without amniotic band sequence: Extending the human phenotype resembling mouse disorganization

ISIDOR B, BAUJAT G, LE CAIGNEC C, PICHON O, MARTIN-COIGNARD D, TOUTAIN A, DAVID A

2009 - Am J Med Genet A 149A(8):1734-9

Congenital skin pedicles are very rare and usually described in association with multiple congenital anomalies. Here, we report on six patients with congenital pedicle skin hamartomatous lesions. Two patients showed a single skin pedicle lesion, one of whom was also shown to have 22q11.2 microdeletion syndrome, and four patients also had severe limb anomalies for which they were originally diagnosed with amniotic band sequence (ABS). We propose that all these infants instead show various forms of the phenotype resembling disorganization in the mouse. This article supports previous reports suggesting that "Disorganization-like" mutations may cause cases with apparent ABS. Owing to these reports, we propose the hypothesis that hamartomatous skin pedicles and "ABS plus" are different phenotypes of the human disorder resembling disorganization.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Cone-rod dystrophy, growth hormone deficiency and spondyloepiphyseal dysplasia: report of a new case without nephronophtisis

ISIDOR B, LE MERRER M, RAMOS E, BARON S, DAVID A

2009 - Am J Med Genet A 149A(4):788-92

Unité(s) : Centre de Génétique Médicale Jean Frézal

Germline mutations in WTX cause a sclerosing skeletal dysplasia but do not predispose to tumorigenesis

JENKINS ZA, VAN KOGELENBERG M, MORGAN T, JEFFS A, FUKUZAWA R, PEARL E, THALLER C, HING AV, PORTEOUS ME, GARCIA-MINAUR S, BOHRING A, LACOMBE D, STEWART F, FISKERSTRAND T, BINDOFF L, BERLAND S, ADES LC, TCHAN M, DAVID A, WILSON LC, HENNEKAM RC, DONNAI D, MANSOUR S, CORMIER-DAIRE V, ROBERTSON SP

2009 - Nat. Genet. 41(1):95-100

Abnormalities in WNT signaling are implicated in a broad range of developmental anomalies and also in tumorigenesis. Here we demonstrate that germline mutations in WTX (FAM123B), a gene that encodes a repressor of canonical WNT signaling, cause an X-linked sclerosing bone dysplasia, osteopathia striata congenita with cranial sclerosis (OSCS; MIM300373). This condition is typically characterized by increased bone density and craniofacial malformations in females and lethality in males. The mouse homolog of WTX is expressed in the fetal skeleton, and alternative splicing implicates plasma membrane localization of WTX as a factor associated with survival in males with OSCS. WTX has also been shown to be somatically inactivated in 11-29% of cases of Wilms tumor. Despite being germline for such mutations, individuals with OSCS are not predisposed to tumor development. The observed phenotypic discordance dependent upon whether a mutation is germline or occurs somatically suggests the existence of temporal or spatial constraints on the action of WTX during tumorigenesis.

Unité(s) : Centre de Génétique Médicale Jean Frézal

A common allele in RPGRIP1L is a modifier of retinal degeneration in ciliopathies

KHANNA H, DAVIS EE, MURGA-ZAMALLOA CA, ESTRADA-CUZCANO A, LOPEZ I, DEN HOLLANDER AI, ZONNEVELD MN, OTHMAN MI, WASEEM N, CHAKAROVA CF, MAUBARET C, DIAZ-FONT A, MACDONALD I, MUZNY DM, WHEELER DA, MORGAN M, LEWIS LR, LOGAN CV, TAN PL, BEER MA, INGLEHEARN CF, LEWIS RA, JACOBSON SG, BERGMANN C, BEALES PL, ATTIE-BITACH T, JOHNSON CA, OTTO EA, BHATTACHARYA SS, HILDEBRANDT F, GIBBS RA, KOENEKOOP RK, SWAROOP A, KATSANIS N

2009 - Nat Genet 41(6):739-745

Despite rapid advances in the identification of genes involved in disease, the predictive power of the genotype remains limited, in part owing to poorly understood effects of second-site modifiers. Here we demonstrate that a polymorphic coding variant of RPGRIP1L (retinitis pigmentosa GTPase regulator-interacting protein-1 like), a ciliary gene mutated in Meckel-Gruber (MKS) and Joubert (JBTS) syndromes, is associated with the development of retinal degeneration in individuals with ciliopathies caused by mutations in other genes. As part of our resequencing efforts of the ciliary proteome, we identified several putative loss-of-function RPGRIP1L mutations, including one common variant, A229T. Multiple genetic lines of evidence showed this allele to be associated with photoreceptor loss in ciliopathies. Moreover, we show that RPGRIP1L interacts biochemically with RPGR, loss of which causes retinal degeneration, and that the Thr229-encoded protein significantly compromises this interaction. Our data represent an example of modification of a discrete phenotype of syndromic disease and highlight the importance of a multifaceted approach for the discovery of modifier alleles of intermediate frequency and effect.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Further clinical and molecular delineation of the 9q subtelomeric deletion syndrome supports a major contribution of EHMT1 haploinsufficiency to the core phenotype

KLEEFSTRA T, VAN ZELST-STAMS WA, NILLESEN WM, CORMIER-DAIRE V, HOUGE G, FOULDS N, VAN DOOREN M, WILLEMSEN MH, PFUNDT R, TURNER A, WILSON M, MCGAUGHRAN J, RAUCH A, ZENKER M, ADAM MP, INNES M, DAVIES C, LOPEZ AG, CASALONE R, WEBER A, BRUETON LA, NAVARRO AD, BRALO MP, VENSELAAR H, STEGMANN SP, YNTEMA HG, VAN BOKHOVEN H, BRUNNER HG

2009 - J Med Genet 46(9):598-606

BACKGROUND: The 9q subtelomeric deletion syndrome (9qSTDS) is clinically characterised by moderate to severe mental retardation, childhood hypotonia and facial dysmorphisms. In addition, congenital heart defects, urogenital defects, epilepsy and behavioural problems are frequently observed. The syndrome can be either caused by a submicroscopic 9q34.3 deletion or by intragenic EHMT1 mutations leading to haploinsufficiency of the EHMT1 gene. So far it has not been established if and to what extent other genes in the 9q34.3 region contribute to the phenotype observed in deletion cases. This study reports the largest cohort of 9qSTDS cases so far. METHODS AND RESULTS: By a multiplex ligation dependent probe amplification (MLPA) approach, the authors identified and characterised 16 novel submicroscopic 9q deletions. Direct sequence analysis of the EHMT1 gene in 24 patients exhibiting the 9qSTD phenotype without such deletion identified six patients with an intragenic EHMT1 mutation. Five of these mutations predict a premature termination codon whereas one mutation gives rise to an amino acid substitution in a conserved domain of the protein. CONCLUSIONS: The data do not provide any evidence for phenotype-genotype correlations between size of the deletions or type of mutations and severity of clinical features. Therefore, the authors confirm the EHMT1 gene to be the major determinant of the 9qSTDS phenotype. Interestingly, five of six patients who had reached adulthood had developed severe psychiatric pathology, which may indicate that EHMT1 haploinsufficiency is associated with neurodegeneration in addition to neurodevelopmental defect.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Mutations in MMP9 and MMP13 Determine the Mode of Inheritance and the Clinical Spectrum of Metaphyseal Anadysplasia

LAUSCH E, KEPPLER R, HILBERT K, CORMIER-DAIRE V, NIKKEL S, NISHIMURA G, UNGER S, SPRANGER J, SUPERTI-FURGA A, ZABEL B

2009 - Am J Hum Genet 85(2):168-178

The matrix metalloproteinases MMP9 and MMP13 catalyze the degradation of extracellular matrix (ECM) components in the growth plate and at the same time cleave and release biologically active molecules stored in the ECM, such as VEGFA. In mice, ablation of Mmp9, Mmp13, or both Mmp9 and Mmp13 causes severe distortion of the metaphyseal growth plate. We report that mutations in either MMP9 or MMP13 are responsible for the human disease metaphyseal anadysplasia (MAD), a heterogeneous group of disorders for which a milder recessive variant and a more severe dominant variant are known. We found that recessive MAD is caused by homozygous loss of function of either MMP9 or MMP13, whereas dominant MAD is associated with missense mutations in the prodomain of MMP13 that determine autoactivation of MMP13 and intracellular degradation of both MMP13 and MMP9, resulting in a double enzymatic deficiency.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Maternal uniparental heterodisomy of chromosome 17 in a patient with nephropathic cystinosis

LEBRE AS, MORINIERE V, DUNAND O, BENSMAN A, MORICHON-DELVALLEZ N, ANTIGNAC C

2009 - Eur J Hum Genet 17(8):1019-23

We report maternal uniparental disomy of chromosome 17 (mat UPD17) in a 2.5-year-old girl presenting infantile cystinosis. This patient was homozygous for the 57 kb deletion encompassing the CTNS gene, frequently found in patients from the European origin. The proband's mother was heterozygous for the deletion and the father did not carry the deletion. We carried out haplotype analysis with polymorphic markers spanning the whole chromosome 17. Informative markers showed the presence of two maternal alleles but no paternal allele for regions spanning the 17q arm and the proximal half of 17p, and only one maternal allele on the distal 17p arm. As deletion of half of 17p is probably not viable, these results suggest mat UPD17 with heterodisomy of 17q and proximal 17p and isodisomy of distal 17p. This is the first demonstration of mat UPD17, in particular of isodisomy 17p, in cystinosis.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U574

NDUFS4 mutations cause Leigh syndrome with predominant brainstem involvement

LESHINSKY-SILVER E, LEBRE AS, MINAI L, SAADA A, STEFFANN J, COHEN S, ROTIG A, MUNNICH A, LEV D, LERMAN-SAGIE T

2009 - Mol Genet Metab 97(3):185-9

Complex I deficiency is a frequent cause of Leigh syndrome. We describe a non-consanguineous Ashkenazi-Sephardic Jewish patient with Leigh syndrome due to complex I deficiency. The clinical and neuroradiological presentation showed predominant brainstem involvement. Blue native polyacrylamide gel electrophoresis analysis revealed an impaired assembly of complex I. The patient was found to be compound heterozygous of two mutations in the NDUFS4 gene: p.Asp119His (a novel mutation) and p.Lys154fs (recently described in an Ashkenazi Jewish family). These findings support the suggestion that the p.Lys154fs mutation in NDUFS4 should be evaluated in Ashkenazi Jewish patients presenting with early onset Leigh syndrome even before enzymatic studies. Our results further demonstrated that NDUFS4 presents a hotspot of mutations in the genetic apparatus of oxidative phosphorylation and the correct assembly of the subunit it encodes is essential for completion of the assembly of complex I.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

[Epidemiology of age related macular degeneration.]

LEVEZIEL N, DELCOURT C, ZERBIB J, DOLLFUS H, KAPLAN J, BENLIAN P, COSCAS G, SOUIED EH, SOUBRANE G

2009 - J Fr Ophtalmol 32(6):440-51

Age-related macular degeneration (ARMD) is a multifactorial and polygenic disease and is the main cause of vision loss in developed countries. The environmental factors of ARMD can modify prevalence and incidence of this disease. This article is a review of the main environmental factors currently recognized as at risk or protective factor for ARMD. Modification of these factors is of crucial importance because it could delay the onset of exudative or atrophic forms of the disease.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Genotype-phenotype correlations in Down syndrome identified by array CGH in 30 cases of partial trisomy and partial monosomy chromosome 21

LYLE R, BENA F, GAGOS S, GEHRIG C, LOPEZ G, SCHINZEL A, LESPINASSE J, BOTTANI A, DAHOUN S, TAINE L, DOCO-FENZY M, CORNILLET-LEFEBVRE P, PELET A, LYONNET S, TOUTAIN A, COLLEAUX L, HORST J, KENNERKNECHT I, WAKAMATSU N, DESCARTES M, FRANKLIN JC, FLORENTIN-ARAR L, KITSIOU S, AIT YAHYA-GRAISON E, COSTANTINE M, SINET PM, DELABAR JM, ANTONARAKIS SE

2009 - Eur J Hum Genet 17(4):454-66

Down syndrome (DS) is one of the most frequent congenital birth defects, and the most common genetic cause of mental retardation. In most cases, DS results from the presence of an extra copy of chromosome 21. DS has a complex phenotype, and a major goal of DS research is to identify genotype-phenotype correlations. Cases of partial trisomy 21 and other HSA21 rearrangements associated with DS features could identify genomic regions associated with specific phenotypes. We have developed a BAC array spanning HSA21q and used array comparative genome hybridization (aCGH) to enable high-resolution mapping of pathogenic partial aneuploidies and unbalanced translocations involving HSA21. We report the identification and mapping of 30 pathogenic chromosomal aberrations of HSA21 consisting of 19 partial trisomies and 11 partial monosomies for different segments of HSA21. The breakpoints have been mapped to within approximately 85 kb. The majority of the breakpoints (26 of 30) for the partial aneuploidies map within a 10-Mb region. Our data argue against a single DS critical region. We identify susceptibility regions for 25 phenotypes for DS and 27 regions for monosomy 21. However, most of these regions are still broad, and more cases are needed to narrow down the phenotypic maps to a reasonable number of candidate genomic elements per phenotype.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Clinical and epidemiological assessment of steroid-resistant nephrotic syndrome associated with the NPHS2 R229Q variant

MACHUCA E, HUMMEL A, NEVO F, DANTAL J, MARTINEZ F, AL-SABBAN E, BAUDOUIN V, ABEL L, GRUNFELD JP, ANTIGNAC C

2009 - Kidney Int 75(7):727-735

Mutations of NPHS2, encoding podocin, are the main cause of autosomal recessive steroid-resistant nephrotic syndrome (NS) presenting in childhood. Adult-onset steroid-resistant NS has been described in patients heterozygous for a pathogenic NPHS2 mutation together with the p.R229Q variant. To determine the frequency and the phenotype of patients carrying the p.R229Q variant, we sequenced the complete coding region of NPHS2 in 455 families (546 patients) non-responsive to immunosuppressive therapy or without relapse after transplantation. Among affected Europeans, the p.R229Q allele was significantly more frequent compared to control individuals. Thirty-six patients from 27 families (11 families from Europe and 14 from South America) were compound heterozygotes for the p.R229Q variant and one pathogenic mutation. These patients had significantly later onset of NS and end stage renal disease than patients with two pathogenic mutations. Among 119 patients diagnosed with NS presenting after 18 years of age, 18 patients were found to have one pathogenic mutation and p.R229Q, but none had two pathogenic mutations. Our study shows that compound heterozygosity for p.R229Q is associated with adult-onset steroid-resistant NS, mostly among patients of European and South American origin. Screening for the p.R229Q variant is recommended in these patients along with further NPHS2 mutation analysis in those carrying the variant.Kidney International advance online publication, 14 January 2009; doi:10.1038/ki.2008.650.

Unité(s) : Néphrologie Adulte, Centre de Génétique Médicale Jean Frézal, Transplantation Adulte, U550, U574

19q13.11 deletion syndrome: a novel clinically recognisable genetic condition identified by array comparative genomic hybridisation

MALAN V, RAOUL O, FIRTH HV, ROYER G, TURLEAU C, BERNHEIM A, WILLATT L, MUNNICH A, VEKEMANS M, LYONNET S, CORMIER-DAIRE V, COLLEAUX L

2009 - J Med Genet 46(9):635-40

BACKGROUND: Deletions of chromosome 19 have rarely been reported, with the exception of some patients with deletion 19q13.2 and Blackfan-Diamond syndrome due to haploinsufficiency of the RPS19 gene. Such a paucity of patients might be due to the difficulty in detecting a small rearrangement on this chromosome that lacks a distinct banding pattern. Array comparative genomic hybridisation (CGH) has become a powerful tool for the detection of microdeletions and microduplications at high resolution in patients with syndromic mental retardation. METHODS AND RESULTS: Using array CGH, this study identified three interstitial overlapping 19q13.11 deletions, defining a minimal critical region of 2.87 Mb, associated with a clinically recognisable syndrome. The three patients share several major features including: pre- and postnatal growth retardation with slender habitus, severe postnatal feeding difficulties, microcephaly, hypospadias, signs of ectodermal dysplasia, and cutis aplasia over the posterior occiput. Interestingly, these clinical features have also been described in a previously reported patient with a 19q12q13.1 deletion. No recurrent breakpoints were identified in our patients, suggesting that no-allelic homologous recombination mechanism is not involved in these rearrangements. CONCLUSIONS: Based on these results, the authors suggest that this chromosomal abnormality may represent a novel clinically recognisable microdeletion syndrome caused by haploinsufficiency of dosage sensitive genes in the 19q13.11 region.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781, Histo-Embryologie - Cytogénétique

Pearson syndrome in the neonatal period: two case reports and review of the literature

MANEA EM, LEVERGER G, BELLMANN F, STANESCU PA, MIRCEA A, LEBRE AS, ROTIG A, MUNNICH A

2009 - J Pediatr Hematol Oncol 31(12):947-51

Pearson syndrome is a multiorgan mitochondrial cytopathy that results from defective oxidative phosphorylation owing to mitochondrial DNA deletions. Prognosis is severe and death occurs in infancy or early childhood. This article describes 2 cases with a severe neonatal onset of the disease. A review of the literature reveals the atypical presentation of the disease in the neonatal period, which is often overlooked and underdiagnosed.

Unité(s) : Centre de Génétique Médicale Jean Frézal

[Clinical variability and diagnosis steps in childhood mitochondrial disease.]

MERCIER S, DE WASCH MJ, LABARTHE F, JARDEL C, LOMBES A, MUNNICH A, TOUTAIN A, NIVET H, SALIBA E, CHANTEPIE A, CASTELNAU P

2009 - Arch Pediatr 16(4):322-30

OBJECTIVES: Mitochondrial respiratory chain deficiencies are known for their high clinical variability. Difficult to diagnose, the prevalence of these diseases is probably underestimated. METHODS: We report 18 children diagnosed with respiratory chain deficiency at the Tours University Hospital over the past 10 years. RESULTS: Three clinical profiles can be distinguished depending on the age at onset of the first symptoms: the neonatal period (4 cases), between 1 month and 2 years of age (10 cases), and after 10 years (4 cases). However, no clinical feature appears specific of any age group. In contrast, respiratory chain analysis on liver biopsy was very informative for all our patients at any age and with any clinical presentation, even with predominant neurological symptoms. CONCLUSIONS: These biochemical analyses support the diagnosis of mitochondrial disorders in view of molecular analysis, which nevertheless frequently remains inconclusive. These investigations should benefit from the new molecular screening technologies based on DNA chips that can identify the genomic mutations responsible for these severe and relatively frequent diseases.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Podocin Inactivation in Mature Kidneys Causes Focal Segmental Glomerulosclerosis and Nephrotic Syndrome

MOLLET G, RATELADE J, BOYER O, MUDA AO, MORISSET L, LAVIN TA, KITZIS D, DALLMAN MJ, BUGEON L, HUBNER N, GUBLER MC, ANTIGNAC C, ESQUIVEL EL

2009 - J Am Soc Nephrol 20(10):2181-2189

Podocin is a critical component of the glomerular slit diaphragm, and genetic mutations lead to both familial and sporadic forms of steroid-resistant nephrotic syndrome. In mice, constitutive absence of podocin leads to rapidly progressive renal disease characterized by mesangiolysis and/or mesangial sclerosis and nephrotic syndrome. Using established Cre-loxP technology, we inactivated podocin in the adult mouse kidney in a podocyte-specific manner. Progressive loss of podocin in the glomerulus recapitulated albuminuria, hypercholesterolemia, hypertension, and renal failure seen in nephrotic syndrome in humans. Lesions of FSGS appeared after 4 wk, with subsequent development of diffuse glomerulosclerosis and tubulointerstitial damage. Interestingly, conditional inactivation of podocin at birth resulted in a gradient of glomerular lesions, including mesangial proliferation, demonstrating a developmental stage dependence of renal histologic patterns of injury. The development of significant albuminuria in this model occurred only after early and focal foot process effacement had progressed to diffuse involvement, with complete absence of podocin immunolabeling at the slit diaphragm. Finally, we identified novel potential mediators and perturbed molecular pathways, including cellular proliferation, in the course of progression of renal disease leading to glomerulosclerosis, using global gene expression profiling.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U574, Néphrologie Pédiatrique

CC2D2A mutations in Meckel and Joubert syndromes indicate a genotype-phenotype correlation

MOUGOU-ZERELLI S, THOMAS S, SZENKER E, AUDOLLENT S, ELKHARTOUFI N, BABARIT C, ROMANO S, SALOMON R, AMIEL J, ESCULPAVIT C, GONZALES M, ESCUDIER E, LEHEUP B, LOGET P, ODENT S, ROUME J, GERARD M, DELEZOIDE AL, KHUNG S, PATRIER S, CORDIER MP, BOUVIER R, MARTINOVIC J, GUBLER MC, BODDAERT N, MUNNICH A, ENCHA-RAZAVI F, VALENTE EM, SAAD A, SAUNIER S, VEKEMANS M, ATTIE-BITACH T

2009 - Hum Mutat 30(11):1574-82

Meckel-Gruber syndrome (MKS) is a lethal fetal disorder characterized by diffuse renal cystic dysplasia, polydactyly, a brain malformation that is usually occipital encephalocele, and/or vermian agenesis, with intrahepatic biliary duct proliferation. Joubert syndrome (JBS) is a viable neurological disorder with a characteristic "molar tooth sign" (MTS) on axial images reflecting cerebellar vermian hypoplasia/dysplasia. Both conditions are classified as ciliopathies with an autosomal recessive mode of inheritance. Allelism of MKS and JBS has been reported for TMEM67/MKS3, CEP290/MKS4, and RPGRIP1L/MKS5. Recently, one homozygous splice mutation with a founder effect was reported in the CC2D2A gene in Finnish fetuses with MKS, defining the 6th locus for MKS. Shortly thereafter, CC2D2A mutations were also reported in JBS. The analysis of the CC2D2A gene in our series of MKS fetuses, identified 14 novel truncating mutations in 11 cases. These results confirm the involvement of CC2D2A in MKS and reveal a major contribution of CC2D2A to the disease. We also identified three missense CC2D2A mutations in two JBS cases. Therefore, and in accordance with the data reported regarding RPGRIP1L, our results indicate phenotype-genotype correlations, as missense and presumably hypomorphic mutations lead to JBS while all null alleles lead to MKS.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U574, Pédiatrie Générale, Radiologie Pédiatrique, U781

Hypomorphic mutations in meckelin (MKS3/TMEM67) cause nephronophthisis with liver fibrosis (NPHP11)

OTTO EA, TORY K, ATTANASIO M, ZHOU W, CHAKI M, PARUCHURI Y, WISE EL, WOLF MT, UTSCH B, BECKER C, NURNBERG G, NURNBERG P, NAYIR A, SAUNIER S, ANTIGNAC C, HILDEBRANDT F

2009 - J Med Genet 46(10):663-70

BACKGROUND: Nephronophthisis (NPHP), a rare recessive cystic kidney disease, is the most frequent genetic cause of chronic renal failure in children and young adults. Mutations in nine genes (NPHP1-9) have been identified. NPHP can be associated with retinal degeneration (Senior-Loken syndrome), brainstem and cerebellar anomalies (Joubert syndrome), or liver fibrosis. METHODS: To identify a causative gene for the subset of patients with associated liver fibrosis, the authors performed a genome wide linkage search in a consanguineous family with three affected patients using 50K SNP microarrays and homozygosity mapping. RESULTS: The authors obtained a significant maximum parametric LOD (logarithm of odds) score of Z(max) = 3.72 on chromosome 8q22 and identified a homozygous missense mutation in the gene MKS3/TMEM67. When examining a worldwide cohort of 62 independent patients with NPHP and associated liver fibrosis we identified altogether four novel mutations (p.W290L, p.C615R, p.G821S, and p.G821R) in five of them. Mutations of MKS3/TMEM67, found recently in Meckel-Gruber syndrome (MKS) type 3 and Joubert syndrome (JBTS) type 6, are predominantly truncating mutations. In contrast, the mutations detected here in patients with NPHP and associated liver fibrosis are exclusively missense mutations. This suggests that they may represent hypomorphic alleles, leading to a milder phenotype compared with the more severe MKS or JBTS phenotype. Additionally, mutation analysis for MKS3/TMEM67 in 120 patients with JBTS yielded seven different (four novel) mutations in five patients, four of whom also presented with congenital liver fibrosis. CONCLUSIONS: Hypomorphic MKS3/TMEM67 mutations cause NPHP with liver fibrosis (NPHP11). This is the first report of MKS3 mutations in patients with no vermian agenesis and without neurological signs. Thus NPHP, JBTS, and MKS represent allelic disorders.

Unité(s) : U574, Centre de Génétique Médicale Jean Frézal

A 24-Mb deletion in 14q in a girl with corpus callosum hypoplasia

OUERTANI I, CHAABOUNI M, TURKI I, LELORC'H M, ATTIE-BITACH T, BEN JEMAA L, KHOUJA-GOUIDER N, CHAABOUNI H

2009 - Eur J Med Genet 52(4):256-9

Interstitial deletions of 14q including band 14q31 are uncommon. We report on a 3 year-old Tunisian girl who had a de novo interstitial deletion of the long arm of chromosome 14. The molecular cytogenetic study has identified the deletion as a del(14)(q24.3q32.2) covering nearly 24Mb. This abnormality was associated to phenotypic manifestations, mainly peculiar face, developmental delay and hypoplastic corpus callosum.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Combination of linkage mapping and microarray-expression analysis identifies NF-kappaB signaling defect as a cause of autosomal-recessive mental retardation

PHILIPPE O, RIO M, CARIOUX A, PLAZA JM, GUIGUE P, MOLINARI F, BODDAERT N, BOLE-FEYSOT C, NITSCHKE P, SMAHI A, MUNNICH A, COLLEAUX L

2009 - Am J Hum Genet 85(6):903-8

Autosomal-recessive inheritance accounts for nearly 25% of nonsyndromic mental retardation (MR), but the extreme heterogeneity of such conditions markedly hampers gene identification. Combining autozygosity mapping and RNA expression profiling in a consanguineous Tunisian family of three MR children with mild microcephaly and white-matter abnormalities identified the TRAPPC9 gene, which encodes a NF-kappaB-inducing kinase (NIK) and IkappaB kinase complex beta (IKK-beta) binding protein, as a likely candidate. Sequencing analysis revealed a nonsense variant (c.1708C>T [p.R570X]) within exon 9 of this gene that is responsible for an undetectable level of TRAPPC9 protein in patient skin fibroblasts. Moreover, TNF-alpha stimulation assays showed a defect in IkBalpha degradation, suggesting impaired NF-kappaB signaling in patient cells. This study provides evidence of an NF-kappaB signaling defect in isolated MR.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781, IRNEM

Hypothalamic lipoma associated with severe obesity

PUGET S, GARNETT MR, LECLERCQ D, PINTO-PRIMARD G, SAMARA-BOUSTANI D, SAINTE-ROSE C, GENEVIEVE D, POLAK M, DE LONLAY P, BRUNELLE F, BENABID AL, BODDAERT N

2009 - J Neurosurg Pediatr 4(2):147-50

The association between hypothalamic dysfunction and obesity is well documented in both clinical and experimental models. The authors describe 2 children who developed obesity that could not be explained by endocrinological, genetic, or eating disorders. In both cases, cranial MR imaging revealed the typical appearance of a lipoma in the paramedian hypothalamus. In the absence of other etiologies, the authors hypothesized that in these 2 children obesity was caused by their hypothalamic lipomas. To the authors' knowledge, these are the first cases of hypothalamic lipomas likely to be causing obesity that have been described in children. These cases highlight the importance of performing cranial MR imaging in children with otherwise unexplained obesity.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Métabolisme, Radiologie Pédiatrique, Endocrinologie Pédiatrique et Gynécologie, Neurochirurgie Pédiatrique

Functional and clinical data of Best vitelliform macular dystrophy patients with mutations in the BEST1 gene

QUERQUES G, ZERBIB J, SANTACROCE R, MARGAGLIONE M, DELPHIN N, ROZET JM, KAPLAN J, MARTINELLI D, DELLE NOCI N, SOUBRANE G, SOUIED EH

2009 - Mol Vis 15(.):2960-72

PURPOSE: To analyze functional and clinical data of Best vitelliform macular dystrophy (VMD) patients with mutations in the BEST1 gene. METHODS: Best VMD patients with BEST1 mutations were evaluated prospectively regarding age, age of onset, best-corrected visual acuity (BCVA), fundus autofluorescence, fluorescein angiography, optical coherence tomography, and electro-oculography. Mutations in BEST1 were established by direct sequencing. RESULTS: Forty-six eyes of 23 patients (10 male, 13 female) were included in the study. We identified nine different BEST1 mutations (3/9 novel), in ten unrelated families. The age of patients ranged between 3 and 75 years; age of onset varied between 2 and 67 years. BCVA ranged between 20/20 and 20/200. On the basis of fundus biomicroscopy with direct illumination, using one widely accepted classification, the macular lesions could be counted as follows: 1. no lesion (normal fovea): eight eyes, five patients carrying a mutation on the BEST1 gene; 2. previtelliform lesions: six eyes, three affected patients; 3. vitelliform lesions: four eyes, two affected patients; 4. pseudohypopyon: three eyes, three affected patients; 5. vitelliruptive lesions (scrambled egg aspect with dispersion of the vitelliform material without sign of atrophy or fibrosis): ten eyes, six affected patients; 6. atrophic lesions (atrophy with or without residual dispersed material): seven eyes, five patients; 7. fibrotic lesions: eight eyes, five patients. Two patients presented unilateral Best VMD. Both eyes of two patients presented multifocal Best VMD features on fundus examination. Six eyes of four patients have been treated for choroidal neovascularization by thermic photocoagulation [one eye], photodynamic therapy [three eyes], and intravitreal ranibizumab injection [two eyes]. Comparison of interfamilial and intrafamilial clinical data between patients did not reveal differences in age, BCVA, and stage of the disease as evaluated by fundus autofluorescence, fluorescein angiography, and optical coherence tomography (p>0.05). Mean BCVA impairment showed a statistically significant correlation to a more advanced stage of the disease (p<0.001). CONCLUSIONS: BEST1 mutations were not correlated with the severity of the functional and clinical data in the Best VMD patients examined.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Compound heterozygous ASPM mutations associated with microcephaly and simplified cortical gyration in a consanguineous Algerian family

SAADI A, BORCK G, BODDAERT N, CHEKKOUR MC, IMESSAOUDENE B, MUNNICH A, COLLEAUX L, CHAOUCH M

2009 - Eur J Med Genet 52(4):180-4

Homozygous mutations in the ASPM gene are a major cause of autosomal recessive primary microcephaly (MCPH). Here we report on a consanguineous Algerian family in which three out of five children presented with severe microcephaly, simplified cortical gyration, mild to severe mental retardation and low to low-normal birth weight. Given the parental consanguinity with the unaffected parents being third cousins once removed, the most probable pattern of inheritance was autosomal recessive. Linkage and mutational analyses identified compound heterozygous truncating mutations within the ASPM gene segregating with MCPH (c.2389C>T [p.Arg797X] and c.7781_7782delAG [p.Gln2594fsX6]). These results highlight some of the pitfalls of genetic analysis in consanguineous families. They also suggest that low birth weight may be a feature of MCPH, a finding that needs confirmation, and confirm that ASPM mutations are associated with simplified cortical gyration.

Unité(s) : Centre de Génétique Médicale Jean Frézal, Radiologie Pédiatrique, U781

The mutation spectrum in RECQL4 diseases

SIITONEN HA, SOTKASIIRA J, BIERVLIET M, BENMANSOUR A, CAPRI Y, CORMIER-DAIRE V, CRANDALL B, HANNULA-JOUPPI K, HENNEKAM R, HERZOG D, KEYMOLEN K, LIPSANEN-NYMAN M, MINY P, PLON SE, RIEDL S, SARKAR A, VARGAS FR, VERLOES A, WANG LL, KAARIAINEN H, KESTILA M

2009 - Eur. J. Human Genet. 17(2):151-158

Mutations in the RECQL4 gene can lead to three clinical phenotypes with overlapping features. All these syndromes, Rothmund-Thomson (RTS), RAPADILINO and Baller-Gerold (BGS), are characterized by growth retardation and radial defects, but RAPADILINO syndrome lacks the main dermal manifestation, poikiloderma that is a hallmark feature in both RTS and BGS. It has been previously shown that RTS patients with RECQL4 mutations are at increased risk of osteosarcoma, but the precise incidence of cancer in RAPADILINO and BGS has not been determined. Here, we report that RAPADILINO patients identified as carriers of the c.1390+2delT mutation (p.Ala420_Ala463del) are at increased risk to develop lymphoma or osteosarcoma (6 out of 15 patients). We also summarize all the published RECQL4 mutations and their associated cancer cases and provide an update of 14 novel RECQL4 mutations with accompanying clinical data.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Nicolaides-Baraitser syndrome: Delineation of the phenotype

SOUSA SB, ABDUL-RAHMAN OA, BOTTANI A, CORMIER-DAIRE V, FRYER A, GILLESSEN-KAESBACH G, HORN D, JOSIFOVA D, KUECHLER A, LEES M, MACDERMOT K, MAGEE A, MORICE-PICARD F, ROSSER E, SARKAR A, SHANNON N, STOLTE-DIJKSTRA I, VERLOES A, WAKELING E, WILSON L, HENNEKAM RC

2009 - Am J Med Genet A 149A(8):1628-40

Nicolaides-Baraitser syndrome (NBS) is an infrequently described condition, thus far reported in five cases. In order to delineate the phenotype and its natural history in more detail, we gathered data on 18 hitherto unreported patients through a multi-center collaborative study, and follow-up data of the earlier reported patients. A detailed comparison of the 23 patients is provided. NBS is a distinct and recognizable entity, and probably has been underdiagnosed until now. Main clinical features are severe mental retardation with absent or limited speech, seizures, short stature, sparse hair, typical facial characteristics, brachydactyly, prominent finger joints and broad distal phalanges. Some of the features are progressive with time. The main differential diagnosis is Coffin-Siris syndrome. There is no important gender difference in occurrence and frequency of the syndrome, and all cases have been sporadic thus far. Microarray analysis performed in 14 of the patients gave normal results. Except for the progressive nature there are no clues to the cause.

Unité(s) : Centre de Génétique Médicale Jean Frézal

Mutations of NPHP2 and NPHP3 in infantile nephronophthisis

TORY K, ROUSSET-ROUVIERE C, GUBLER MC, MORINIERE V, PAWTOWSKI A, BECKER C, GUYOT C, GIE S, FRISHBERG Y, NIVET H, DESCHENES G, COCHAT P, GAGNADOUX MF, SAUNIER S, ANTIGNAC C, SALOMON R

2009 - Kidney Int 75(8):839-847

Nephronophthisis is an autosomal recessive chronic tubulointerstitial disease that progresses to end-stage renal disease (ESRD) in about 10% of cases during infancy. Mutations in the INVS (NPHP2) gene were found in a few patients with infantile nephronophthisis. Mutations of NPHP3, known to be associated with adolescent nephronophthisis, were found in two patients with early-onset ESRD. Here we screened 43 families with infantile nephronophthisis (ESRD less than 5 years of age) for NPHP2 and NPHP3 mutations and determined genotype-phenotype correlations. In this cohort there were 16 families with NPHP2 mutations and NPHP3 mutations in seven. Three patients carried only one heterozygous mutation in NPHP3. ESRD arose during the first 2 years of life in 16 of 18 patients with mutations in NPHP2, but in only two patients with mutations in NPHP3. Renal morphology, characterized by hyper-echogenic kidneys on ultrasound and tubular lesions with interstitial fibrosis on histology, was similar in the two patient groups. The kidney sizes were highly diverse and ultrasound-visualized cysts were present in a minority of cases. Extra-renal anomalies were found in 80% of the entire cohort including hepatic involvement (50%), cardiac valve or septal defects (20%) and recurrent bronchial infections (18%). We show that NPHP3 mutations in both infantile and adolescent nephronophthisis point to a common pathophysiological mechanism despite their different clinical presentations.Kidney International advance online publication, 28 January 2009; doi:10.1038/ki.2008.662.

Unité(s) : Néphrologie Pédiatrique, Centre de Génétique Médicale Jean Frézal, U574

Expanding CEP290 mutational spectrum in ciliopathies

TRAVAGLINI L, BRANCATI F, ATTIE-BITACH T, AUDOLLENT S, BERTINI E, KAPLAN J, PERRAULT I, IANNICELLI M, MANCUSO B, RIGOLI L, ROZET JM, SWISTUN D, TOLENTINO J, DALLAPICCOLA B, GLEESON JG, VALENTE EM, INTERNATIONAL JSG, ZANKL A, LEVENTER R, GRATTAN-SMITH P, JANECKE A, D'HOOGHE M, SZNAJER Y, VAN COSTER R, DEMERLEIR L, DIAS K, MOCO C, MOREIRA A, KIM CA, MAEGAWA G, PETKOVIC D, ABDEL-SALAM GM, ABDEL-ALEEM A, ZAKI MS, MARTI I, QUIJANO-ROY S, SIGAUDY S, DE LONLAY P, ROMANO S, TOURAINE R, KOENIG M, LAGIER-TOURENNE C, MESSER J, COLLIGNON P, WOLF N, PHILIPPI H, KITSIOU TZELI S, HALLDORSSON S, JOHANNSDOTTIR J, LUDVIGSSON P, PHADKE SR, UDANI V, STUART B, MAGEE A, LEV D, MICHELSON M, BEN-ZEEV B, FISCHETTO R, BENEDICENTI F, STANZIAL F, BORGATTI R, ACCORSI P, BATTAGLIA S, FAZZI E, GIORDANO L, PINELLI L, BOCCONE L, BIGONI S, FERLINI A, DONATI MA, CARIDI G, DIVIZIA MT, FARAVELLI F, GHIGGERI G, PESSAGNO A, BRIGUGLIO M, BRIUGLIA S, SALPIETRO CD, TORTORELLA G, ADAMI A, CASTORINA P, LALATTA F, MARRA G, RIVA D, SCELSA B, SPACCINI L, UZIEL G, DEL GIUDICE E, LAVERDA AM, LUDWIG K, PERMUNIAN A, SUPPIEJ A, SIGNORINI S, UGGETTI C, BATTINI R, DI GIACOMO M, CILIO MR, DI SABATO ML, LEUZZI V, PARISI P, POLLAZZON M, SILENGO M, DE VESCOVI R, GRECO D, ROMANO C, CAZZAGON M, SIMONATI A, AL-TAWARI AA, BASTAKI L, MEGARBANE A, SABOLIC AVRAMOVSKA V, DE JONG MM, STROMME P, KOUL R, RAJAB A, AZAM M, BARBOT C, MARTORELL SAMPOL L, RODRIGUEZ B, PASCUAL-CASTROVIEJO I, TEBER S, ANLAR B, COMU S, KARACA E, KAYSERILI H, YUKSEL A, AKCAKUS M, AL GAZALI L, SZTRIHA L, NICHOLL D, WOODS CG, BENNETT C, HURST J, SHERIDAN E, BARNICOAT A, HENNEKAM R, LEES M, BLAIR E, BERNES S, SANCHEZ H, CLARK AE, DEMARCO E, DONAHUE C, SHERR E, HAHN J, SANGER TD, GALLAGER TE, DOBYNS WB, DAUGHERTY C, KRISHNAMOORTHY KS, SARCO D, WALSH CA, MCKANNA T, MILISA J, CHUNG WK, DE VIVO DC, RAYNES H, SCHUBERT R, SEWARD A, BROOKS DG, GOLDSTEIN A, CALDWELL J, FINSECKE E, MARIA BL, HOLDEN K, CRUSE RP, SWOBODA KJ, VISKOCHIL D

2009 - Am J Med Genet A 149A(10):2173-80

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781, Métabolisme

In Vitro studies of non poly alanine PHOX2B mutations argue against a loss-of-function mechanism for congenital central hypoventilation

TROCHET D, MATHIEU Y, PONTUAL LD, SAVARIRAYAN R, MUNNICH A, BRUNET JF, LYONNET S, GORIDIS C, AMIEL J

2009 - Hum. Mutat. 30(2):E421-E431

A wide range of autonomic dysfunctions, i.e. Central Hypoventilation Syndromes, Hirschsprung disease and Tumours of the Sympathetic Nervous System have been ascribed to heterozygous PHOX2B mutations in man. The PHOX2B mutations reported include polyalanine expansions in a 20 alanines tract, missense, frameshift mutations and nonsense mutation. Some genotype/phenotype correlations have been drawn, but the molecular mechanism(s) underlying them remain(s) unclear. So far, loss-of-function, gain-of-function and dominant negative effects have been proposed as disease-causing mechanisms for polyalanine expansions. Indeed, mutant with an expanded polyalanine tract result in decreased transactivation of known target genes and protein misfolding leading to oligomerisation in vitro for all expansions and to cytoplasmic protein aggregation for longer expansions. We extended the molecular studies to other non-polyalanine expansion mutations and show that most PHOX2B protein mutants oligomerize even in the absence of the normal 20 alanines tract. Conversely, a premature stop codon mutation in a CHS patient leads to the production of an N-terminally truncated protein by re-initiation of translation that does not form oligomers. Therefore, PHOX2B misfolding is not the only mechanism leading to dysfunction of the ventilatory autonomic system. (c) 2008 Wiley-Liss, Inc.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Secondary creatine deficiency in ornithine delta-aminotransferase deficiency

VALAYANNOPOULOS V, BODDAERT N, MENTION K, TOUATI G, BARBIER V, CHABLI A, SEDEL F, KAPLAN J, DUFIER JL, SEIDENWURM D, RABIER D, SAUDUBRAY JM, DE LONLAY P

2009 - Mol Genet Metab 97(2):109-13

AIMS: Ornithine delta-aminotransferase (OAT) deficiency causes gyrate atrophy (GA) of the retina, as a consequence of high plasma ornithine concentrations. Because creatine synthesis requires the conversion of arginine and glycine into ornithine and guanidinoacetate, high ornithine concentration inhibits this reaction thus causing secondary creatine deficiency. The aim of this study was to evaluate the neuropsychological features and creatine metabolism in patients with GA. METHODS: The study involved 7 GA patients, aged from 11 to 27 years who underwent neuropsychological evaluation and cerebral proton magnetic resonance spectroscopy (MRS). RESULTS: Neurocognitive impairment was found in 5/7 patients, including mental retardation (3/7), school failure (1/7), major visuospatial dyspraxia (1/7), aggressive behavior (3/7) and epilepsy (2/7). Two patients had normal neuropsychological evaluation. Cerebral proton magnetic resonance spectroscopy revealed a profound creatine deficiency in all patients. MRS data were confirmed by decreased levels of creatine and/or guanidinoacetate in plasma and urine in all patients. CONCLUSIONS: In our group of patients with GA, we found a high prevalence of neurological impairment, not reported so far, and possibly related to secondary creatine deficiency and hyperornithinemia. We propose to treat mentally retarded GA patients with high doses of creatine, as it may normalize brain creatine levels and help to reduce ornithine levels.

Unité(s) : Biochimie Métabolique, Métabolisme, Radiologie Pédiatrique, U781, Ophtalmologie, Centre de Génétique Médicale Jean Frézal

Multiple OXPHOS deficiency in the liver of a patient with CblA methylmalonic aciduria sensitive to vitamin B(12)

VALAYANNOPOULOS V, HUBERT L, BENOIST JF, ROMANO S, ARNOUX JB, CHRETIEN D, KAPLAN J, FAKHOURI F, RABIER D, ROTIG A, LEBRE AS, MUNNICH A, DE KEYZER Y, DE LONLAY P

2009 - J Inherit Metab Dis 32(2):159-62

An adult patient with methylmalonic aciduria due to defective cobalamin synthesis (CblA) responsive to vitamin B(12) presented suddenly with severe visual impairment ascribed to optic atrophy followed by a fatal multiorgan failure and lactic acidosis but low methylmalonic acid in plasma and urine. Multiple deficiency of oxidative phosphorylation was found in the patient's liver. We suggest that patients with B(12)-sensitive methylmalonic aciduria who have a milder clinical course should be carefully monitored for long-term complications.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781, Biochimie Métabolique

Uromodulin mutations causing familial juvenile hyperuricaemic nephropathy lead to protein maturation defects and retention in the endoplasmic reticulum

WILLIAMS SE, REED AA, GALVANOVSKIS J, ANTIGNAC C, GOODSHIP T, KARET FE, KOTANKO P, LHOTTA K, MORINIERE V, WILLIAMS P, WONG W, RORSMAN P, THAKKER RV

2009 - Hum Mol Genet 18(16):2963-74

Familial juvenile hyperuricaemic nephropathy (FJHN), an autosomal dominant disorder, is caused by mutations in the UMOD gene, which encodes Uromodulin, a glycosylphosphatidylinositol-anchored protein that is expressed in the thick ascending limb of the loop of Henle and excreted in the urine. Uromodulin contains three epidermal growth factor (EGF)-like domains, a cysteine-rich region which includes a domain of eight cysteines and a zona pellucida (ZP) domain. Over 90% of UMOD mutations are missense, and 62% alter a cysteine residue, implicating a role for protein misfolding in the disease. We investigated 20 northern European FJHN probands for UMOD mutations. Wild-type and mutant Uromodulins were functionally studied by expression in HeLa cells and by the use of western blot analysis and confocal microscopy. Six different UMOD missense mutations (Cys32Trp, Arg185Gly, Asp196Asn, Cys217Trp, Cys223Arg and Gly488Arg) were identified. Patients with UMOD mutations were phenotypically similar to those without UMOD mutations. The mutant Uromodulins had significantly delayed maturation, retention in the endoplasmic reticulum (ER) and reduced expression at the plasma membrane. However, Gly488Arg, which is the only mutation we identified in the ZP domain, was found to be associated with milder in vitro abnormalities and to be the only mutant Uromodulin detected in conditioned medium from transfected cells, indicating that the severity of the mutant phenotypes may depend on their location within the protein. Thus, FJHN-causing Uromodulin mutants are retained in the ER, with impaired intracellular maturation and trafficking, thereby indicating mechanisms whereby Uromodulin mutants may cause the phenotype of FJHN.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U574

Acute infantile liver failure due to mutations in the TRMU gene

ZEHARIA A, SHAAG A, PAPPO O, MAGER-HECKEL AM, SAADA A, BEINAT M, KARICHEVA O, MANDEL H, OFEK N, SEGEL R, MAROM D, ROTIG A, TARASSOV I, ELPELEG O

2009 - Am J Hum Genet 85(3):401-7

Acute liver failure in infancy accompanied by lactic acidemia was previously shown to result from mtDNA depletion. We report on 13 unrelated infants who presented with acute liver failure and lactic acidemia with normal mtDNA content. Four died during the acute episodes, and the survivors never had a recurrence. The longest follow-up period was 14 years. Using homozygosity mapping, we identified mutations in the TRMU gene, which encodes a mitochondria-specific tRNA-modifying enzyme, tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase. Accordingly, the 2-thiouridylation levels of the mitochondrial tRNAs were markedly reduced. Given that sulfur is a TRMU substrate and its availability is limited during the neonatal period, we propose that there is a window of time whereby patients with TRMU mutations are at increased risk of developing liver failure.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U781

Dominant Renin Gene Mutations Associated with Early-Onset Hyperuricemia, Anemia, and Chronic Kidney Failure

ZIVNA M, HULKOVA H, MATIGNON M, HODANOVA K, VYLET'AL P, KALBACOVA M, BARESOVA V, SIKORA J, BLAZKOVA H, ZIVNY J, IVANEK R, STRANECKY V, SOVOVA J, CLAES K, LERUT E, FRYNS JP, HART PS, HART TC, ADAMS JN, PAWTOWSKI A, CLEMESSY M, GASC JM, GUBLER MC, ANTIGNAC C, ELLEDER M, KAPP K, GRIMBERT P, BLEYER AJ, KMOCH S

2009 - Am J Hum Genet 85(2):204-213

Through linkage analysis and candidate gene sequencing, we identified three unrelated families with the autosomal-dominant inheritance of early onset anemia, hypouricosuric hyperuricemia, progressive kidney failure, and mutations resulting either in the deletion (p.Leu16del) or the amino acid exchange (p.Leu16Arg) of a single leucine residue in the signal sequence of renin. Both mutations decrease signal sequence hydrophobicity and are predicted by bioinformatic analyses to damage targeting and cotranslational translocation of preprorenin into the endoplasmic reticulum (ER). Transfection and in vitro studies confirmed that both mutations affect ER translocation and processing of nascent preprorenin, resulting either in reduced (p.Leu16del) or abolished (p.Leu16Arg) prorenin and renin biosynthesis and secretion. Expression of renin and other components of the renin-angiotensin system was decreased accordingly in kidney biopsy specimens from affected individuals. Cells stably expressing the p.Leu16del protein showed activated ER stress, unfolded protein response, and reduced growth rate. It is likely that expression of the mutant proteins has a dominant toxic effect gradually reducing the viability of renin-expressing cells. This alters the intrarenal renin-angiotensin system and the juxtaglomerular apparatus functionality and leads to nephron dropout and progressive kidney failure. Our findings provide insight into the functionality of renin-angiotensin system and stress the importance of renin analysis in families and individuals with early onset hyperuricemia, anemia, and progressive kidney failure.

Unité(s) : Centre de Génétique Médicale Jean Frézal, U574

Risk assessment of acute vascular events in congenital disorder of glycosylation type Ia

ARNOUX JB, BODDAERT N, VALAYANNOPOULOS V, ROMANO S, BAHI-BUISSON N, DESGUERRE I, DE KEYZER Y, MUNNICH A, BRUNELLE F, SETA N, DAUTZENBERG MD, DE LONLAY P

2008 - Mol. Genet. Metab. 93(4):444-449

The congenital disorder of glycosylation type Ia (CDG-Ia) presents a broad clinical spectrum. Some patients suffer from acute vascular events (thrombosis and bleeding) and stroke-like events. No correlations have been made between the marked hemostasis abnormalities of CDG-Ia and the occurrence of acute vascular events. We report on 6 patients with CDG-Ia presenting vascular events, then we analyze the clinical and hemostasis data of 39 CDG-Ia patients described in the literature, 17 with vascular events (E) and 21 unscathed from any event (EF), to determine the risk factors for acute vascular events in CDG-Ia. Acute vascular events occurred in patients younger than 15 years, especially with fever and prolonged immobilization. Hemostasis and liver cytolysis were statistically abnormal in patients younger than 5 years whatever the occurrence of vascular events and they normalized with time. Higher factors VIII and IX activities were statistically observed in the E cluster (p=0.03) compared to the EF cluster. The activity/antigenicity ratio for protein C (p=0.02) was also higher in the E group. CDG-Ia patients younger than 15 years old are at risk of acute vascular events. The paradoxical results-abnormal VIII and IX factors in EF patients and normal results in E patients, while XI, antithrombin, protein C, ASAT and ALAT are abnormal in both groups, could suggest a disequilibrium between prothrombotic and antithrombotic factors in the E group. Vascular events may also occur in patients where glycoproteins are proportionally more hypoglycosylated, particularly protein C.

Unité(s) : Génétique Médicale Pédiatrique, Laboratoire d'Hématologie, Métabolisme, Radiologie Pédiatrique

Angiogenesis in systemic sclerosis: Impaired expression of vascular endothelial growth factor receptor 1 in endothelial progenitor-derived cells under hypoxic conditions

AVOUAC J, WIPFF J, GOLDMAN O, RUIZ B, COURAUD PO, CHIOCCHIA G, KAHAN A, BOILEAU C, UZAN G, ALLANORE Y

2008 - Arthritis Rheum. 58(11):3550-3561

OBJECTIVE: To assess angiogenesis and explore the expression and regulation of vascular endothelial growth factor (VEGF), VEGF receptor 1 (VEGFR-1), and VEGFR-2, the leading mediators of angiogenesis, in SSc patients and controls. METHODS: Late-outgrowth endothelial progenitor cells (EPCs), isolated from the peripheral blood of systemic sclerosis (SSc) patients and controls, and human umbilical vein endothelial cells (HUVECs) were assessed under normal and hypoxic conditions. Genomic background was evaluated in a large case-control study (including 659 patients with SSc and 511 controls) using tag single-nucleotide polymorphisms on VEGFR1 and VEGFR2 genes. RESULTS: EPCs from SSc patients had the phenotype of genuine endothelial cells and displayed in vitro angiogenic properties similar to those of HUVECs and control EPCs under basal conditions, as determined by flow cytometry, tube formation, and migration assay. However, after 6 hours of hypoxic exposure, EPCs from SSc patients exhibited lower induced expression of VEGFR-1 at the messenger RNA and protein levels, but similar VEGF and VEGFR-2 expression, compared with HUVECs or EPCs from healthy controls. There was no evidence of defective expression of hypoxia-inducible factor 1alpha. These results were supported by the lower serum levels of soluble VEGFR-1 found in SSc patients (n = 187) compared with healthy controls (n = 48) (mean +/- SD 163.7 +/- 98.5 versus 210.4 +/- 109.5 pg/ml; P = 0.0042). These abnormalities did not seem to be related to genomic background. CONCLUSION: Our findings shed new light on the possible role of VEGFR-1 in the main vascular disturbances that occur in SSc and lead to more severe disease.

Unité(s) : U781, Génétique Médicale Pédiatrique

Nephronophthisis-like nephritis associated with fibrous dysplasia of bone

BACCHETTA J, CHAPURLAT R, BOUVIER R, ANTIGNAC C, DUBOURG L, KOHLER R, DELMAS PD, COCHAT P

2008 - Pediat. Nephrol. 23(9):1559-1563

Nephronophthisis is a chronic tubulointerstitial nephritis with autosomal recessive inheritance whose evolution to end-stage renal disease is insidious but constant. Fibrous dysplasia of bone is characterized by focal replacement of normal bone and marrow with abnormal bone and fibrous tissue. We report on a young boy initially diagnosed with fibrous dysplasia of bone, who underwent renal investigation because of treatment with pamidronate. He presented with mild proteinuria (albuminuria/creatininuria 19 mg/mmol) and decreased glomerular filtration rate (GFR) (79 ml/min per 1.73 m(2) body surface area) leading to kidney biopsy, which showed nephronophthisis-like lesions, but neither NPHP1 gene deletion nor UMOD (uromodulin) mutation were identified. No association between fibrous dysplasia of bone and nephronophthisis has yet been described. Nephronophthisis-like nephritis associated with fibrous dysplasia of bone might represent a possible new syndrome in the nephronophthisis and medullary cystic kidney disease complex. However, a fortuitous association between these two conditions is also possible.

Unité(s) : Génétique Médicale Pédiatrique, U574

Spectrum of epilepsy in terminal 1p36 deletion syndrome

BAHI-BUISSON N, GUTTIERREZ-DELICADO E, SOUFFLET C, RIO M, CORMIER-DAIRE V, LACOMBE D, HERON D, VERLOES A, ZUBERI S, BURGLEN L, AFENJAR A, MOUTARD ML, EDERY P, NOVELLI A, BERNARDINI L, DULAC O, NABBOUT R, PLOUIN P, BATTAGLIA A

2008 - Epilepsia 49(3):509-515

Purpose: Previous reports have summarized the seizures types occurring in 1p36 deletion syndrome. To better define the spectrum of epilepsy, we studied 91 patients (median age 7.8 years) with confirmed 1p36 deletion. Methods: Based on clinical charts, we retrospectively analyzed the evolution of both the EEG findings and seizures. Results: Epilepsy occurred in 53 patients (58.2%), with onset at a median 2.75 months. First seizures were generalized tonic (8 cases), tonic and clonic (6) or myoclonic (12), simple partial (6), or complex partial (14). Thereafter, 20 patients (21.9%) developed infantile spasms with hypsarrhythmia, at a median age of 5 months. High doses of oral steroids were tried in nine cases, with a prompt remission of seizures in six. Among them, five were seizure-free at the time of evaluation. Conversely, two of three nonresponders to steroids developed severe and refractory epilepsy. At the time of evaluation, 32 patients were seizure-free, from a median age of 1.8 years. Nineteen patients (20.9%) had developed refractory epilepsy with polymorphic seizures, including generalized tonic and tonic-clonic seizures (13) combined with myoclonic seizures (11) and atypical absences (3), atonic seizures (2), or complex partial seizures (3). The EEG showed focal, multifocal or generalized spikes, polyspike, and waves, with poverty of the usual background rhythmic activities. Conclusions: Early epilepsy is a frequent finding in 1p36 deletion syndrome with infantile spasms as of the most common features that can contribute to a poor clinical outcome. Early diagnosis and management of infantile spasm in this condition is mandatory.

Unité(s) : Explorations Fonctionnelles, Génétique Médicale Pédiatrique, Neurologie, U663

The three stages of epilepsy in patients with CDKL5 mutations

BAHI-BUISSON N, KAMINSKA A, BODDAERT N, RIO M, AFENJAR A, GERARD M, GIULIANO F, MOTTE J, HERON D, MOREL MA, PLOUIN P, RICHELME C, DES PORTES V, DULAC O, PHILIPPE C, CHIRON C, NABBOUT R, BIENVENU T

2008 - Epilepsia 49(6):1027-1037

Mutations in the X-linked cyclin-dependent kinase-like 5 (CDKL5) gene are responsible for a severe encephalopathy with early epilepsy. So far, the electroclinical phenotype remains largely unknown and no clear genotype-phenotype correlations have been established. Purpose: To characterize the epilepsy associated with CDKL5 mutations and to look for a relationship between the genotype and the course of epilepsy. Methods: We retrospectively analyzed the electroclinical phenotypes of 12 patients aged from 2.5 to 19 years diagnosed with pathogenic CDKL5 mutations and one patient with a novel intronic sequence variation of uncertain pathogenicity and examined whether the severity of the epilepsy was linked to the type and location of mutations. Results: The epilepsy course reveals three successive stages: (Stage I) early epilepsy (onset 1-10 weeks) with normal interictal electroencephalogram (EEG) (10/13) despite frequent convulsive seizures; (Stage II) epileptic encephalopathy with infantile spasms (8/8) and hypsarrhythmia (8/8). At the age of evaluation, seven patients were seizure free and six had developed refractory epilepsy (stage III) with tonic seizures and myoclonia (5/6). Interestingly, the patients carrying a CDKL5 mutations causing a truncation of the catalytic domain tended to develop a more frequent refractory epilepsy than patients with mutations located downstream (4/6, 66.6% versus 1/6, 16%) although, these trends are not yet significant. Discussion: Our data contribute to a better definition of the epileptic phenotype in CDKL5 mutations, and might give some clues to a potential relationship between the phenotype and the genotype in these patients.

Unité(s) : Explorations Fonctionnelles, Génétique Médicale Pédiatrique, Neurologie, Radiologie Pédiatrique, U663

Key clinical features to identify girls with CDKL5 mutations

BAHI-BUISSON N, NECTOUX J, ROSAS-VARGAS H, MILH M, BODDAERT N, GIRARD B, CANCES C, VILLE D, AFENJAR A, RIO M, HERON D, N'GUYEN-MOREL MA, ARZIMANOGLOU A, PHILIPPE C, JONVEAUX P, CHELLY J, BIENVENU T

2008 - Brain 131(10):2647-2661

Mutations in the human X-linked cyclin-dependent kinase-like 5 (CDKL5) gene have been shown to cause infantile spasms as well as Rett syndrome (RTT)-like phenotype. To date, less than 25 different mutations have been reported. So far, there are still little data on the key clinical diagnosis criteria and on the natural history of CDKL5-associated encephalopathy. We screened the entire coding region of CDKL5 for mutations in 183 females with encephalopathy with early seizures by denaturing high liquid performance chromatography and direct sequencing, and we identified in 20 unrelated girls, 18 different mutations including 7 novel mutations. These mutations were identified in eight patients with encephalopathy with RTT-like features, five with infantile spasms and seven with encephalopathy with refractory epilepsy. Early epilepsy with normal interictal EEG and severe hypotonia are the key clinical features in identifying patients likely to have CDKL5 mutations. Our study also indicates that these patients clearly exhibit some RTT features such as deceleration of head growth, stereotypies and hand apraxia and that these RTT features become more evident in older and ambulatory patients. However, some RTT signs are clearly absent such as the so called RTT disease profile (period of nearly normal development followed by regression with loss of acquired fine finger skill in early childhood and characteristic intensive eye communication) and the characteristic evolution of the RTT electroencephalogram. Interestingly, in addition to the overall stereotypical symptomatology (age of onset and evolution of the disease) resulting from CDKL5 mutations, atypical forms of CDKL5-related conditions have also been observed. Our data suggest that phenotypic heterogeneity does not correlate with the nature or the position of the mutations or with the pattern of X-chromosome inactivation, but most probably with the functional transcriptional and/or translational consequences of CDKL5 mutations. In conclusion, our report show that search for mutations in CDKL5 is indicated in girls with early onset of a severe intractable seizure disorder or infantile spasms with severe hypotonia, and in girls with RTT-like phenotype and early onset seizures, though, in our cohort, mutations in CDKL5 account for about 10% of the girls affected by these disorders.

Unité(s) : Génétique Médicale Pédiatrique, Neurologie, U663, Radiologie Pédiatrique

Refinement of cortical dysgeneses spectrum associated with TUBA1A mutations

BAHI-BUISSON N, POIRIER K, BODDAERT N, SAILLOUR Y, CASTELNAU L, PHILIP N, BUYSE G, VILLARD L, JORIOT S, MARRET S, BOURGEOIS M, VAN ESCH H, LAGAE L, AMIEL J, HERTZ-PANNIER L, ROUBERTIE A, RIVIER F, PINARD JM, BELDJORD C, CHELLY J

2008 - J. Med. Genet. 45(10):647-653

OBJECTIVE: We have recently shown that de novo mutations in the TUBA1A gene are responsible for a wide spectrum of neuronal migration disorders. To better define the range of these abnormalities, we searched for additional mutations in a cohort of 100 patients with lissencephaly spectrum for whom no mutation was identified in DCX, LIS1 and ARX genes and compared these data to five previously described patients with TUBA1A mutations. RESULTS: We detected de novo TUBA1A mutations in six patients and highlight the existence of a prominent form of TUBA1A related lissencephaly. In four patients, the mutations identified, c.1190T>C (p.L397P), c.1265G>A (p.R422H), c.1264C>T (p.R422C), c.1306G>T (p.G436R), have not been reported before and in two others, the mutation corresponds to a recurrent missense mutation, c.790C>T (p.R264C), likely to be a hot spot of mutation. All together, it emerges that the TUBA1A related lissencephaly spectrum ranges from perisylvian pachygyria, in the less severe form, to posteriorly predominant pachygyria in the most severe, associated with dysgenesis of the anterior limb of the internal capsule and mild to severe cerebellar hypoplasia. When compared with a large series of lissencephaly of other origins (ILS17, ILSX or unknown origin), these features appear to be specific to TUBA1A related lissencephaly. In addition, TUBA1A mutated patients share a common clinical phenotype that consists of congenital microcephaly, mental retardation and diplegia/tetraplegia. CONCLUSIONS: Our data highlight the presence of consistent and specific abnormalities that should allow the differentiation of TUBA1A related lissencephalies from those related to LIS1, DCX and ARX genes.

Unité(s) : Génétique Médicale Pédiatrique, Neurochirurgie Pédiatrique, Neurologie, Radiologie Pédiatrique

Osteogenesis imperfecta, diagnosis information (clinical and genetic classification)

BAUJAT G, LEBRE AS, CORMIER-DAIRE V, LE MERRER M

2008 - Archives Pédiatrie 15(5):789-791

Unité(s) : Génétique Médicale Pédiatrique

Achondroplasia

BAUJAT G, LEGEAI-MALLET L, FINIDORI G, CORMIER-DAIRE V, LE MERRER M

2008 - Best Pract. Res. Clin. Rheumatol. 22(1):3-18

Achondroplasia (MIM 100800) is the most common non-lethal skeletal dysplasia. Its incidence is between one in 10 000 and one in 30 000. The phenotype is characterized by rhizomelic disproportionate short stature, enlarged head, midface hypoplasia, short hands and lordotic lumbar spine, associated with normal cognitive development. This autosomal-dominant disorder is caused by a gain-of-function mutation in the gene encoding the type 3 receptor for fibroblast growth factor (FGFR3); in more than 95% of cases, the mutation is G380R. The diagnosis is suspected on physical examination and confirmed by different age-related radiological features. Anticipatory and management care by a multidisciplinary team will prevent and treat complications, including cervical cord compression, conductive hearing loss and thoracolumbar gibbosity. Weight counselling, psychosocial guidance and professional integration programmes play an important role in the global quality of life of these patients and their families.

Unité(s) : Génétique Médicale Pédiatrique

Glucose tolerance and insulin secretion, morbidity, and death in patients with cystic fibrosis

BISMUTH E, LABORDE K, TAUPIN P, VELHO G, RIBAULT V, JENNANE F, GRASSET E, SERMET-GAUDELUS I, DE BLIC J, LENOIR G, ROBERT JJ

2008 - J. Pediat. 152(4):540-545

OBJECTIVES: To describe the history, mechanisms, and consequences of cystic fibrosis (CF)-related diabetes, from childhood to early adulthood. STUDY DESIGN: Pancreatic beta-cell function was estimated from the plasma insulin/glucose ratios during oral glucose tolerance test (total area under the curve and deltaI(30-0min)/G(30min), homeostasis model assessment [HOMA]%B), insulin sensitivity with the HOMA%S index, in 237 children with CF (109 boys, 128 girls). Progression of glucose metabolism abnormalities was evaluated by analysis for interval censored data; rates of pulmonary transplantation and death by Kaplan-Meier analysis. RESULTS: Impaired glucose tolerance was found in 20% of patients at 10 years, 50% at 15 years, 75% at 20 years, 82% at 30 years; for diabetes, >20% at 15 year, 45% at 20 years, 70% at 30 years; for insulin treatment, 30% at 20 years, 40% at 30 years. Early impairment was associated with lower survival rates and higher rates of lung transplantation. The area under the curve(glucose) correlated with decreased body mass index and height. Decrease in early insulin secretion (deltaI(30-0min)/G(30min)) was associated with impaired glucose tolerance, in all estimates of insulin secretion with diabetes. HOMA%S did not differ between the groups. Increased inflammation correlated with insulin resistance and impaired glucose tolerance. CONCLUSIONS: CF-related diabetes, mainly because of beta-cell deficiency, is frequent early in life and associated with impaired nutritional state and growth, increased rates of terminal respiratory failure, and death.

Unité(s) : Biostatistique, Diabétologie Pédiatrique, Explorations Fonctionnelles, Génétique Médicale Pédiatrique, Pneumologie et Asthmologie Pédiatriques

Clinical, cellular, and neuropathological consequences of AP1S2 mutations: further delineation of a recognizable X-linked mental retardation syndrome

BORCK G, MOLLA-HERMAN A, BODDAERT N, ENCHA-RAZAVI F, PHILIPPE A, ROBEL L, DESGUERRE I, BRUNELLE F, BENMERAH A, MUNNICH A, COLLEAUX L

2008 - Hum. Mutat. 29(7):966-974

Mutations in the AP1S2 gene, encoding the sigma1B subunit of the clathrin-associated adaptor protein complex (AP)-1, have been recently identified in five X-linked mental retardation (XLMR) families, including the original family with Fried syndrome. Studying four patients in two unrelated families in which AP1S2 nonsense and splice-site mutations segregated, we found that affected individuals presented, in addition to previously described features, with elevated protein levels in cerebrospinal fluid (CSF). Moreover, computed tomography scans demonstrated that the basal ganglia calcifications associated with AP1S2 mutations appeared during childhood and might be progressive. Based on these observations, we propose that AP1S2 mutations are responsible for a clinically recognizable XLMR and autism syndrome associating hypotonia, delayed walking, speech delay, aggressive behavior, brain calcifications, and elevated CSF protein levels. Using the AP-2 complex, in which the sigma subunit is encoded by one single gene, as a model system, we demonstrated that sigma subunits are essential for the stability of human AP complexes. By contrast, no major alteration of the stability, subcellular localization, and function of the AP-1 complex was observed in fibroblasts derived from a patient carrying an AP1S2 mutation. Similarly, neither macro- nor microscopic defects were observed in the brain of an affected fetus. Altogether, these data suggest that the absence of an AP-1 defect in peripheral tissues is due to functional redundancy among AP-1 sigma subunits (sigma1A, sigma1B, and sigma1C) and that the phenotype observed in our patients results from a subtle and brain-specific defect of the AP-1-dependent intracellular protein traffic. Hum Mutat 29(7), 966-974, 2008. (c) 2008 Wiley-Liss, Inc.

Unité(s) : Génétique Médicale Pédiatrique, Histo-Embryologie - Cytogénétique, Neurologie, Pédo-Psychiatrie, Radiologie Pédiatrique, U781

Mutations in the cilia gene ARL13B lead to the classical form of Joubert syndrome

CANTAGREL V, SILHAVY JL, BIELAS SL, SWISTUN D, MARSH SE, BERTRAND JY, AUDOLLENT S, ATTIE-BITACH T, HOLDEN KR, DOBYNS WB, TRAVER D, AL GAZALI L, ALI BR, LINDNER TH, CASPARY T, OTTO EA, HILDEBRANDT F, GLASS IA, LOGAN CV, JOHNSON CA, BENNETT C, BRANCATI F, VALENTE EM, WOODS CG, GLEESON JG

2008 - Amer. J. Hum. Genet. 83(2):170-179

Joubert syndrome (JS) and related disorders are a group of autosomal-recessive conditions sharing the "molar tooth sign" on axial brain MRI, together with cerebellar vermis hypoplasia, ataxia, and psychomotor delay. JS is suggested to be a disorder of cilia function and is part of a spectrum of disorders involving retinal, renal, digital, oral, hepatic, and cerebral organs. We identified mutations in ARL13B in two families with the classical form of JS. ARL13B belongs to the Ras GTPase family, and in other species is required for ciliogenesis, body axis formation, and renal function. The encoded Arl13b protein was expressed in developing murine cerebellum and localized to the cilia in primary neurons. Overexpression of human wild-type but not patient mutant ARL13B rescued the Arl13b scorpion zebrafish mutant. Thus, ARL13B has an evolutionarily conserved role mediating cilia function in multiple organs.

Unité(s) : Génétique Médicale Pédiatrique, U781

Clinical outcome in children with chronic recurrent multifocal osteomyelitis

CATALANO-PONS C, COMTE A, WIPFF J, QUARTIER P, FAYE A, GENDREL D, DUQUESNE A, CIMAZ R, JOB-DESLANDRE C

2008 - Rheumatology 47(9):1397-1399

OBJECTIVE: To determine the clinical outcome of children with chronic recurrent multifocal osteomyelitis (CRMO). METHODS:We retrospectively reviewed clinical, biological and radiological data of children with CRMO at five French paediatric centres. Outcome data were obtained through review of hospital charts and questionnaires sent to all patients to assess disease activity and educational and vocational achievement. RESULTS: Forty patients were assessed (34 females and 6 males) with a median age at diagnosis of 11.5 yrs (range 2-17). Median number of initial bony lesions was 2 at onset, and 3.5 over disease course. Median time since diagnosis was 3.5 yrs (range 0.5-15) and median duration of active disease 2.7 yrs (range 0.5-13.5). Nine (22.5%) patients had psychological or physical sequelae. Twenty-nine children (72.5%) responded to the questionnaire. Twenty-six had no physical disability as judged by the HAQ 0-1, two had moderate disability (HAQ: 1-2) and one had severe disability (HAQ: 2-3). Seventeen patients (58.6%) had active disease at follow-up (after 6 months to 15 yrs since diagnosis) and continued to have pain (median value of visual analogue scale: 10/100). CRMO had interfered with patient's education in two cases. CONCLUSIONS: Clinical outcome of children with CRMO is generally good, but a sizeable proportion of patients have active disease at follow-up, and a minority of patients can have a severe and prolonged disease course despite intensive treatments. Further studies are required to determine predictive factors for severe disease.

Unité(s) : Génétique Médicale Pédiatrique, Immuno-Hématologie-Rhumatologie Pédiatriques

[Sleep-disordered breathing in children.]

COHEN-GOGO S, DO NGOC THANH C, LEVY D, METREAU J, MORNAND P, PARISOT P, FAUROUX B

2008 - Arch Pediatr 16(2):123-131

Unité(s) : Cardiologie Pédiatrique, Centre de Génétique Médicale Jean Frézal

Spondylo-epi-metaphyseal dysplasia

CORMIER-DAIRE V

2008 - Best Pract. Res. Clin. Rheumatol. 22(1):33-44

The spondylo-epi-metaphyseal dysplasias (SEMD) are a heterogeneous group of disorders comprising more than 20 distinct entities with differing modes of inheritance, all defined by the combination of vertebral, epiphyseal and metaphyseal abnormalities. The presenting symptom of SEMD patients is usually disproportionate short stature. The diagnosis is either based on the specificity of the skeletal manifestations or on the presence of characteristic extraskeletal features which may appear during the course of the disease, highlighting the importance of follow-up of SEMD patients. The complications are variable but epiphyseal dysplasia is often a predominant feature, and the course of the disease is marked by premature osteoarthritis. A systematic survey of odontoid hypoplasia responsible for atlantoaxial instability with a risk of spinal cord is also required.

Unité(s) : U781, Génétique Médicale Pédiatrique

Chromosome 11p15 paternal isodisomy in focal forms of neonatal hyperinsulinism

DAMAJ L, LE LORCH M, VERKARRE V, WERL C, HUBERT L, NIHOUL-FEKETE C, AIGRAIN Y, DE KEYZER Y, ROMANA SP, BELLANNE-CHANTELOT C, DE LONLAY P, JAUBERT F

2008 - J. Clin. Endocrinol. Metabol. 93(12):4941-4947

Context: Focal forms of congenital hyperinsulinism are due to a constitutional heterozygous mutation of paternal origin in the ABCC8 gene, more often than the KCNJ11 gene, located in the 11p11 region. This mutation is associated with the loss of the maternally inherited 11p11 to 11p15 region in the lesion. We investigated the possible occurrence of a compensatory duplication of the paternal 11p11-11p15 region. Materials and Methods: A combined immunohistochemistry and fluorescent in situ hybridization (FISH) study on beta-cell interphase nuclei with probes covering two genes located in this region (ABCC8 and CDKN1C genes) was performed in four cases of focal forms of hyperinsulinism. Results: i) beta-cells in the lesions of four cases of focal congenital hyperinsulinism were diploid for chromosomes 11 and 13, and ii) the 11p11 to 11p12 and the 11p14 to 11p15 regions containing ABCC8 and CDKN1C genes respectively were present with two copies. Loss of the maternal allele was confirmed in these focal lesions with microsatellite markers flanking the ABCC8 and CDKN1C genes, while a heterozygous mutation in the ABCC8 gene was inherited from the father. Conclusion: there is a duplication of the paternal allele on chromosome 11 in the focal forms of hyperinsulinism lesion. The paternal isodisomy observed rendered the beta-cells homozygous for ABCC8 mutation and harbored a K channel defect in the lesion similar to that observed in diffuse forms of congenital hyperinsulinism.

Unité(s) : Anatomie Pathologique, Chirurgie Viscérale Pédiatrique, Génétique Médicale Pédiatrique, U781

Mutations in STAT3 and IL12RB1 impair the development of human IL-17-producing T cells

DE BEAUCOUDREY L, PUEL A, FILIPE-SANTOS O, COBAT A, GHANDIL P, CHRABIEH M, FEINBERG J, VON BERNUTH H, SAMARINA A, JANNIERE L, FIESCHI C, STEPHAN JL, BOILEAU C, LYONNET S, JONDEAU G, CORMIER-DAIRE V, LE MERRER M, HOARAU C, LEBRANCHU Y, LORTHOLARY O, CHANDESRIS MO, TRON F, GAMBINERI E, BIANCHI L, RODRIGUEZ-GALLEGO C, ZITNIK SE, VASCONCELOS J, GUEDES M, VITOR AB, MARODI L, CHAPEL H, REID B, ROIFMAN C, NADAL D, REICHENBACH J, CARAGOL I, GARTY BZ, DOGU F, CAMCIOGLU Y, GULLE S, SANAL O, FISCHER A, ABEL L, STOCKINGER B, PICARD C, CASANOVA JL

2008 - J. Exp. Med. 205(7):1543-1550

The cytokines controlling the development of human interleukin (IL) 17-producing T helper cells in vitro have been difficult to identify. We addressed the question of the development of human IL-17-producing T helper cells in vivo by quantifying the production and secretion of IL-17 by fresh T cells ex vivo, and by T cell blasts expanded in vitro from patients with particular genetic traits affecting transforming growth factor (TGF) beta, IL-1, IL-6, or IL-23 responses. Activating mutations in TGFB1, TGFBR1, and TGFBR2 (Camurati-Engelmann disease and Marfan-like syndromes) and loss-of-function mutations in IRAK4 and MYD88 (Mendelian predisposition to pyogenic bacterial infections) had no detectable impact. In contrast, dominant-negative mutations in STAT3 (autosomal-dominant hyperimmunoglobulin E syndrome) and, to a lesser extent, null mutations in IL12B and IL12RB1 (Mendelian susceptibility to mycobacterial diseases) impaired the development of IL-17-producing T cells. These data suggest that IL-12Rbeta1- and STAT-3-dependent signals play a key role in the differentiation and/or expansion of human IL-17-producing T cell populations in vivo.

Unité(s) : U550, U768, U781, Infectiologie, Génétique Médicale Pédiatrique, Immuno-Hématologie-Rhumatologie Pédiatriques

Delineation of Late Onset Hypoventilation Associated with Hypothalamic Dysfunction Syndrome

DE PONTUAL L, TROCHET D, CAILLAT-ZUCMAN S, ABOU-SHENAB OA, BOUGNERES P, CROW Y, CUNNINGHAM S, ESTEVA B, HEBERLE LC, LEGER J, PINTO G, POLAK M, SHAFIK MH, STRAUS C, TRANG H, MUNNICH A, LYONNET S, DESGUERRE I, AMIEL J

2008 - Pediat. Res. 64(6):689-694

Late Onset Central Hypoventilation Syndrome associated with Hypothalamic Dysfunction (LO-CHS/HD) is a distinct entity among the clinically and genetically heterogeneous group of patients with Late Onset Central Hypoventilation. Here we report a series of 13 patients with LO-CHS/HD. Rapid onset obesity is the first symptom of HD followed by hypoventilation with a mean delay of 18 months. The outcome remains poor for this group of patients and would benefit from early diagnosis in order to anticipate ventilation and possible metabolic disorders. Tumor predisposition is more frequent than initially suspected and as high as 40% in this series. These tumors of the sympathetic nervous system (TSNS) are usually differentiated and do not significantly worsen the prognosis. We report a familial case with recurrence in siblings. The cause underlying LO-CHS/HD remains poorly understood although recurrence in sibs argues for a monogenic disorder. We ruled out PHOX2B, ASCL1 and NECDIN as disease-causing genes by direct sequencing in our series of patients and discuss possible disease-causing mechanisms.

Unité(s) : Endocrinologie Pédiatrique et Gynécologie, Génétique Médicale Pédiatrique, Laboratoire d'Immunologie, Neurologie, U781

Juvenile osteoporosis

DELALANDE D, JUNG C, LABEDAN I, LECHEVALIER P, MADRE C, ROCHE S, KONE-PAUT I

2008 - Archives Pédiatrie 15(4):420-430

Osteoporosis is induced by a disorder of the bone turnover that generates an accelerated destruction process and leads to the rarefaction of the protein matrix. The RANK-L/RANK/OPG system is the main actor of the bone remodelling regulation. Juvenile osteoporoses may have primary or secondary aetiologies. The main causes include constitutional bone fragilities, and osteoporoses, which are secondary to chronic inflammatory diseases and sustained steroid treatment. Etiologic diagnosis relies on a clinical basis, and is often made too lately when complications occur. Osteodensitometry is a sensitive and noninvasive tool for measuring mineral bone density in children. The reliability of results is limited by the variations due to patients' age, gender, pubertal stage, and by the length of bone pieces. The optimal treatment of osteoporosis is preventive, and includes accurate nutritional diet, D vitamin-calcium supplementation and regular physical activity. Biphosphonates are used for treatment of symptomatic osteoporoses. Careful utilization is required in childhood because their late potential secondary effects are still unknown. New antiresorptive drugs and other that stimulate osteoformation are successfully used in adults. Their effects have not been studied in the paediatric population.

Unité(s) : Génétique Médicale Pédiatrique

A human mutation in Phox2b causes lack of CO2 chemosensitivity, fatal central apnea, and specific loss of parafacial neurons

DUBREUIL V, RAMANANTSOA N, TROCHET D, VAUBOURG V, AMIEL J, GALLEGO J, BRUNET JF, GORIDIS C

2008 - Proc. Natl. Acad. Sci. USA 105(3):1067-1072

Breathing is maintained and controlled by a network of neurons in the brainstem that generate respiratory rhythm and provide regulatory input. Central chemoreception, the mechanism for CO(2) detection that provides an essential stimulatory input, is thought to involve neurons located near the medullary surface, whose nature is controversial. Good candidates are serotonergic medullary neurons and glutamatergic neurons in the parafacial region. Here, we show that mice bearing a mutation in Phox2b that causes congenital central hypoventilation syndrome in humans breathe irregularly, do not respond to an increase in CO(2), and die soon after birth from central apnea. They specifically lack Phox2b-expressing glutamatergic neurons located in the parafacial region, whereas other sites known or supposed to be involved in the control of breathing are anatomically normal. These data provide genetic evidence for the essential role of a specific population of medullary interneurons in driving proper breathing at birth and will be instrumental in understanding the etiopathology of congenital central hypoventilation syndrome.

Unité(s) : Génétique Médicale Pédiatrique, U781

Effectiveness of Anastrozole and Cyproterone Acetate in Two Brothers with Familial Male Precocious Puberty

EYSSETTE-GUERREAU S, PINTO G, SULTAN A, LE MERRER M, SULTAN C, POLAK M

2008 - J. Pediatr. Endocrinol. Metab. 21(10):995-1002

Testotoxicosis is a rare form of precocious puberty caused by a constitutively activating mutation in the luteinizing hormone receptor (LHR) gene. Symptoms include rapid virilization, accelerated growth and reduced adult height. We describe a rare association of testotoxicosis with a metaphyseal chondrodysplasia called cartilage-hair hypoplasia (CHH) and report two brothers with testotoxicosis after 4 years of treatment. The brothers had a T5771 mutation in the LHR gene. One brother also presented CHH. The older brother was treated with ketoconazole, then with the aromatase inhibitor anastrozole and the anti-androgen cyproterone acetate. The younger brother received this combination as first-line therapy. Clinical improvements included reductions in growth velocity and bone maturation rate, which should result in taller adult stature. Tolerance was good. Conclusion: Combined treatment with anastrozole and cyproterone acetate is effective in improving the prognosis of adult height in testotoxicosis.

Unité(s) : Endocrinologie Pédiatrique et Gynécologie, Génétique Médicale Pédiatrique

Submicroscopic duplications of the hydroxysteroid dehydrogenase HSD17B10 and the E3 ubiquitin ligase HUWE1 are associated with mental retardation

FROYEN G, CORBETT M, VANDEWALLE J, JARVELA I, LAWRENCE O, MELDRUM C, BAUTERS M, GOVAERTS K, VANDELEUR L, VAN ESCH H, CHELLY J, SANLAVILLE D, VAN BOKHOVEN H, ROPERS HH, LAUMONNIER F, RANIERI E, SCHWARTZ CE, ABIDI F, TARPEY PS, FUTREAL PA, WHIBLEY A, RAYMOND FL, STRATTON MR, FRYNS JP, SCOTT R, PEIPPO

2008 - Amer. J. Hum. Genet. 82(2):432-443

Submicroscopic copy-number imbalances contribute significantly to the genetic etiology of human disease. Here, we report a novel microduplication hot spot at Xp11.22 identified in six unrelated families with predominantly nonsyndromic XLMR. All duplications segregate with the disease, including the large families MRX17 and MRX31. The minimal, commonly duplicated region contains three genes: RIBC1, HSD17B10, and HUWE1. RIBC1 could be excluded on the basis of its absence of expression in the brain and because it escapes X inactivation in females. For the other genes, expression array and quantitative PCR analysis in patient cell lines compared to controls showed a significant upregulation of HSD17B10 and HUWE1 as well as several important genes in their molecular pathways. Loss-of-function mutations of HSD17B10 have previously been associated with progressive neurological disease and XLMR. The E3 ubiquitin ligase HUWE1 has been implicated in TP53-associated regulation of the neuronal cell cycle. Here, we also report segregating sequence changes of highly conserved residues in HUWE1 in three XLMR families; these changes are possibly associated with the phenotype. Our findings demonstrate that an increased gene dosage of HSD17B10, HUWE1, or both contribute to the etiology of XLMR and suggest that point mutations in HUWE1 are associated with this disease too.

Unité(s) : Génétique Médicale Pédiatrique

Alterations of the IKBKG locus and diseases: an update and a report of 13 novel mutations

FUSCO F, PESCATORE A, BAL E, GHOUL A, PACIOLLA M, LIOI MB, D'URSO M, HADJ-RABIA S, BODEMER C, BONNEFONT JP, MUNNICH A, MIANO MG, SMAHI A, URSINI MV

2008 - Hum. Mutat. 29(5):595-604

Mutations in the inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase gamma (IKBKG), also called nuclear factor-kappaB (NF-kB) essential modulator (NEMO), gene are the most common single cause of incontinentia pigmenti (IP) in females and anhydrotic ectodermal dysplasia with immunodeficiency (EDA-ID) in males. The IKBKG gene, located in the Xq28 chromosomal region, encodes for the regulatory subunit of the inhibitor of kappaB (IkB) kinase (IKK) complex required for the activation of the NF-kB pathway. Therefore, the remarkably heterogeneous and often severe clinical presentation reported in IP is due to the pleiotropic role of this signaling transcription pathway. A recurrent exon 4_10 genomic rearrangement in the IKBKG gene accounts for 60 to 80% of IP-causing mutations. Besides the IKBKG rearrangement found in IP females (which is lethal in males), a total of 69 different small mutations (missense, frameshift, nonsense, and splice-site mutations) have been reported, including 13 novel ones in this work. The updated distribution of all the IP- and EDA-ID-causing mutations along the IKBKG gene highlights a secondary hotspot mutation in exon 10, which contains only 11% of the protein. Furthermore, familial inheritance analysis revealed an unexpectedly high incidence of sporadic cases (>65%). The sum of the observations can aid both in determining the molecular basis of IP and EDA-ID allelic diseases, and in genetic counseling in affected families.

Unité(s) : Génétique Médicale Pédiatrique, U781

A novel renal carbonic anhydrase type III plays a role in proximal tubule dysfunction

GAILLY P, JOURET F, MARTIN D, DEBAIX H, PARREIRA KS, NISHITA T, BLANCHARD A, ANTIGNAC C, WILLNOW TE, COURTOY PJ, SCHEINMAN SJ, CHRISTENSEN EI, DEVUYST O

2008 - Kidney Int. 74(1):52-61

Dysfunction of the proximal tubule (PT) is associated with variable degrees of solute wasting and low-molecular-weight proteinuria. We measured metabolic consequences and adaptation mechanisms in a model of inherited PT disorders using PT cells of ClC-5-deficient (Clcn5Y/-) mice, a well-established model of Dent's disease. Compared to cells taken from control mice, those from the mutant mice had increased expression of markers of proliferation (Ki67, proliferative cell nuclear antigen (PCNA), and cyclin E) and oxidative scavengers (superoxide dismutase I and thioredoxin). Transcriptome and protein analyses showed fourfold induction of type III carbonic anhydrase in a kidney-specific manner in the knockout mice located in scattered PT cells. Kidney-specific carbonic anhydrase type III (CAIII) upregulation was confirmed in other mice lacking the multiligand receptor megalin and in a patient with Dent's disease due to an inactivating CLCN5 mutation. The type III enzyme was specifically detected in the urine of mice lacking ClC-5 or megalin, patients with Dent's disease, and in PT cell lines exposed to oxidative stress. Our study shows that lack of PT ClC-5 in mice and men is associated with CAIII induction, increased cell proliferation, and oxidative stress.

Unité(s) : Génétique Médicale Pédiatrique, U574

Fibrodysplasia ossificans progressiva

GEHANNO P, BERCHE P, HERCOT O, D'ARRAS L, CABRILLAC-RIVES S, DEROBERT E, CHONE C, KAPLAN FS, LE MERRER M, GLASER DL, PIGNOLO RJ, GOLDSBY RE, KITTERMAN JA, GROPPE J, SHORE EM

2008 - Méd. Mal. Infec. 38(2P2):8

Fibrodysplasia ossificans progressiva (FOP), a rare and disabling genetic condition of congenital skeletal malformations and progressive heterotopic ossification (HO), is the most catastrophic disorder of HO in humans. Episodic disease flare-ups are precipitated by soft tissue injury, and immobility is cumulative. Recently, a recurrent mutation in activin receptor IA/activin-like kinase 2 (ACVR1/ALK2), a bone morphogenetic protein (BMP) type I receptor, was reported in all sporadic and familial cases of classic FOP, making this one of the most highly specific disease-causing mutations in the human genome. The discovery of the FOP gene establishes a critical milestone in understanding FOP, reveals a highly conserved target for drug development in the transforming growth factor (TGF)-beta/BMP signalling pathway, and compels therapeutic approaches for the development of small molecule signal transduction inhibitors for ACVR1/ALK2. Present management involves early diagnosis, assiduous avoidance of iatrogenic harm, and symptomatic amelioration of painful flare-ups. Effective therapies for FOP, and possibly for other common conditions of HO, may potentially be based on future interventions that block ACVR1/ALK2 signalling.

Unité(s) : Laboratoire de Microbiologie, Génétique Médicale Pédiatrique

Revisiting metatropic dysplasia: Presentation of a series of 19 novel patients and review of the literature

GENEVIEVE D, LE MERRER M, FEINGOLD J, MUNNICH A, MAROTEAUX P, CORMIER-DAIRE V

2008 - Amer. J. Med. Genet. A 146A(8):992-996

Metatropic dysplasia (MD-OMIM: 156530 and 250600) is a rare chondrodysplasia characterized by short limbs with limitation and enlargement of joints and usually severe kyphoscoliosis, first described in 1893. Up until now, 81 other patients have been reported. The phenotypic variability of MD has led to a classification based on radiological anomalies dividing into three different types: a lethal autosomal recessive form, an autosomal recessive non-lethal form and a non-lethal autosomal dominant form with less severe radiographs manifestations and a better clinical outcome. Here, we report on clinical and radiological features of 19 novel MD patients. We describe new radiological features, including precocious calcification of hyoid and cricoid cartilage, irregular and squared-off calcaneal bones and severe hypoplasia of the anterior portion of first cervical vertebrae. In addition, the observation of an overlap between the autosomal recessive non-lethal form and the non-lethal autosomal dominant form, the rarity of sibship recurrences and the observation of vertical transmissions of MD in the literature argue in favor of an autosomal dominant mode of inheritance for all MD types. This hypothesis is reinforced by the use of the statistical single ascertainment method that rejects the hypothesis of an autosomal recessive mode of inheritance responsible for MD. Therefore, we propose that recurrence in sibs is due to gonadal mosaicism. (c) 2008 Wiley-Liss, Inc.

Unité(s) : Génétique Médicale Pédiatrique, U781

Thromboxane synthase mutations in an increased bone density disorder (Ghosal syndrome)

GENEVIEVE D, PROULLE V, ISIDOR B, BELLAIS S, SERRE V, DJOUADI F, PICARD C, VIGNON-SAVOYE C, BADER-MEUNIER B, BLANCHE S, DE VERNEJOUL MC, LEGEAI-MALLET L, FISCHER AM, LE MERRER M, DREYFUS M, GAUSSEM P, MUNNICH A, CORMIER-DAIRE V

2008 - Nat. Genet. 40(3):284-286

Studying consanguineous families with Ghosal hematodiaphyseal dysplasia syndrome (GHDD), a disorder of increased bone density, we identified mutations in TBXAS1, which encodes thromboxane synthase (TXAS). TXAS, an enzyme of the arachidonic acid cascade, produces thromboxane A(2) (TXA(2)). Platelets from subjects with GHDD showed a specific deficit in arachidonic acid-produced aggregation. We also found that TXAS and TXA(2) modulated expression of TNFSF11 and TNFRSF11B (encoding RANKL and osteoprotegerin (OPG), respectively) in primary cultured osteoblasts.

Unité(s) : Génétique Médicale Pédiatrique, U781

Successful preimplantation genetic diagnosis for autosomal recessive polycystic kidney disease by haplotype-analysis (vol 16, pg 152, 2008)

GIGAREL N, FRYDMAN N, BURLET P, KERBRAT V, TACHDJIAN G, FANCHIN R, ANTIGNAC C, FRYDMAN R, MUNNICH A, STEFFANN J

2008 - Reprod. Biomed. Online 16(3):463

Unité(s) : U781, Génétique Médicale Pédiatrique

Preimplantation genetic diagnosis for autosomal recessive polycystic kidney disease

GIGAREL N, FRYDMAN N, BURLET P, KERBRAT V, TACHDJIAN G, FANCHIN R, ANTIGNAC C, FRYDMAN R, MUNNICH A, STEFFANN J

2008 - Reprod. Biomed. Online 16(1):152-158

Autosomal recessive polycystic kidney disease (ARPKD) is one of the most common hereditary renal cystic diseases, and is caused by mutations in the PKHD1 gene. Due to the poor prognosis, there is a strong demand for prenatal diagnosis. Preimplantation genetic diagnosis (PGD) represents an alternative because it avoids the physical and emotional trauma of a pregnancy termination in the case of an affected fetus. A standardized single-cell diagnostic procedure was developed, based on haplotype analysis, enabling PGD to be offered to couples at risk of transmitting ARPKD. Six linked markers within (D6S1714 and D6S243), or in close proximity to (D6S272, D6S436, KIAA0057, D6S1662) the PKHD1 gene were tested by multiplex nested-polymerase chain reaction (PCR), using a Qiagen multiplex PCR kit. PCR analyses were carried out on 50 single lymphocytes. The amplification rate was excellent (100%), with an allele drop-out (ADO) rate ranging from 0 to 8%. Five PGD cycles were performed and 23 embryos were biopsied and analysed using this test. Transferable embryos were obtained in 4 cycles, resulting in two pregnancies and the birth of a healthy boy. This standardized diagnostic procedure allowed the detection of recombination, contamination, and ADO events, providing high assay accuracy with wide applicability.

Unité(s) : U781, Génétique Médicale Pédiatrique

Jean Frezal and the development of medical genetics

GILGENKRANTZ S, MUNNICH A, BRIARD ML, LE MERRER M, FEINGOLD J, MATTEI JF

2008 - M S-Méd. Sci. 24(11):991-996

Unité(s) : U781, Génétique Médicale Pédiatrique

miR-122, a paradigm for the role of microRNAs in the liver

GIRARD M, JACQUEMIN E, MUNNICH A, LYONNET S, HENRION-CAUDE A

2008 - J. Hepatol. 48(4):648-656

Recent studies have uncovered profound and unexpected roles for a family of tiny regulatory RNAs, known as microRNAs (miRNAs), in the control of diverse aspects of hepatic function and dysfunction, including hepatocyte growth, stress response, metabolism, viral infection and proliferation, gene expression, and maintenance of hepatic phenotype. In liver cancer, misexpression of specific miRNAs suggests diagnostic and prognostic significance. Here, we review the biology of the most abundant miRNA in human liver, miR-122, and consider the diversity of its roles in the liver. We provide a compilation of all miRNAs expressed in the liver, and consider some possible therapeutic opportunities for exploiting miRNAs in the different settings of liver diseases.

Unité(s) : Génétique Médicale Pédiatrique, U781

Novel mutation and atlantoaxial dislocation in two siblings from India with Dyggve-Melchior-Clausen syndrome

GIRISHA KM, CORMIER-DAIRE V, HEUERTZ S, PHADKE RV, PHADKE SR

2008 - Eur. J. Med. Genet 51(3):251-256

Dyggve-Melchior-Clausen syndrome is a rare variety of spondyloepimetaphyseal dysplasia which often resembles Morquio syndrome. We describe two siblings from India with the condition and report a novel homozygous mutation in them (c.1172_1173insC). One of them had atlantoaxial dislocation.

Unité(s) : Génétique Médicale Pédiatrique, U781

Population history and infrequent mutations: how old is a rare mutation? GUCY2D as a worked example

HANEIN S, PERRAULT I, GERBER S, DELPHIN N, BENEZRA D, SHALEV S, CARMI R, FEINGOLD J, DUFIER JL, MUNNICH A, KAPLAN J, ROZET JM, JEANPIERRE M

2008 - Eur. J. Human Genet. 16(1):115-123

The mosaic pattern of haplotypes observed around a single mutation results from one or several founder events. The difficulties involved in calculating the age of the variant are greatly reduced by assuming a single event, but this simplification may bias analysis of the genealogy of the mutation. However, if it is assumed that more than one founder event occurred, the number of genealogies is very large and the likelihood of every possible tree could not be realistically calculated. A multipoint approach is required, given the number of independent variables needed to describe a complex bifurcating genealogy. Starting from the observation that a limited number of parameters is needed for calculation of the simplest models of bifurcating genealogies, we show that the probability density of a two-ancestor model genealogy can be simply described as an algebraic function in a closed form, two coalescence times being calculated simultaneously without compromising accuracy. Implementation in a Bayesian framework is facilitated by the simplicity of the function, which describes the reciprocal relationship between the region of complete linkage disequilibrium and the branch length of the tree. We illustrate the use of haplotype information about allele-sharing decay around a mutation as a genetic clock, using data for two GUCY2D mutations in Mediterranean populations.European Journal of Human Genetics (2008) 16, 115-123; doi:10.1038/sj.ejhg.5201905; published online 8 August 2007.

Unité(s) : Génétique Médicale Pédiatrique, Ophtalmologie, U781

Autosomal dominant spondylocarpotarsal synostosis syndrome: phenotypic homogeneity and genetic heterogeneity

ISIDOR B, CORMIER-DAIRE V, LE MERRER M, LEFRANCOIS T, HAMEL A, LE CAIGNEC C, DAVID A, JACQUEMONT S

2008 - Amer. J. Med. Genet. A 146A(12):1593-1597

Spondylocarpotarsal synostosis syndrome (SCT) (OMIM 272460), originally thought to be a failure of normal spine segmentation, is characterized by progressive fusion of vertebras and associates unsegmented bars, scoliosis, short stature, carpal and tarsal synostosis. Cleft palate, sensorineural or mixed hearing loss, joint limitation, clinodactyly, and dental enamel hypoplasia are variable manifestations. Twenty-five patients have been reported. Thirteen affected individuals were siblings from six families and four of these families were consanguineous. In four of those families, Krakow et al. [Krakow et al. (2004) Nat Genet 36:405-410] found homozygosity or compound heterozygosity for mutations in the gene encoding FLNB. This confirmed autosomal recessive inheritance of the disorder. We report on two new patients (a mother and her son) representing the first case of autosomal dominant inheritance. These patients met the clinical and radiological criteria for SCT and did not present any features which could exclude this diagnosis. Molecular analysis failed to identify mutations in NOG and FLNB. SCT is therefore, genetically heterogeneous. Both dominant and autosomal recessive forms of inheritance should be considered during genetic counseling.

Unité(s) : Génétique Médicale Pédiatrique

Somatic and germline activating mutations of the ALK kinase receptor in neuroblastoma

JANOUEIX-LEROSEY I, LEQUIN D, BRUGIERES L, RIBEIRO A, DE PONTUAL L, COMBARET V, RAYNAL V, PUISIEUX A, SCHLEIERMACHER G, PIERRON G, VALTEAU-COUANET D, FREBOURG T, MICHON J, LYONNET S, AMIEL J, DELATTRE O

2008 - Nature 455(7215):967-970

Neuroblastoma, a tumour derived from the peripheral sympathetic nervous system, is one of the most frequent solid tumours in childhood. It usually occurs sporadically but familial cases are observed, with a subset of cases occurring in association with congenital malformations of the neural crest being linked to germline mutations of the PHOX2B gene. Here we conducted genome-wide comparative genomic hybridization analysis on a large series of neuroblastomas. Copy number increase at the locus encoding the anaplastic lymphoma kinase (ALK) tyrosine kinase receptor was observed recurrently. One particularly informative case presented a high-level gene amplification that was strictly limited to ALK, indicating that this gene may contribute on its own to neuroblastoma development. Through subsequent direct sequencing of cell lines and primary tumour DNAs we identified somatic mutations of the ALK kinase domain that mainly clustered in two hotspots. Germline mutations were observed in two neuroblastoma families, indicating that ALK is a neuroblastoma predisposition gene. Mutated ALK proteins were overexpressed, hyperphosphorylated and showed constitutive kinase activity. The knockdown of ALK expression in ALK-mutated cells, but also in cell lines overexpressing a wild-type ALK, led to a marked decrease of cell proliferation. Altogether, these data identify ALK as a critical player in neuroblastoma development that may hence represent a very attractive therapeutic target in this disease that is still frequently fatal with current treatments.

Unité(s) : Génétique Médicale Pédiatrique, U781

Cell functions impaired by frataxin deficiency are restored by drug-mediated iron relocation

KAKHLON O, MANNING H, BREUER W, MELAMED-BOOK N, LU C, CORTOPASSI G, MUNNICH A, CABANTCHIK ZI

2008 - Blood 112(13):5219-5227

Various human disorders are associated with misdistribution of iron within or across cells. Friedreich ataxia (FRDA), a deficiency in the mitochondrial iron-chaperone frataxin, results in defective use of iron and its misdistribution between mitochondria and cytosol. We assessed the possibility of functionally correcting the cellular properties affected by frataxin deficiency with a siderophore capable of relocating iron and facilitating its metabolic use. Adding the chelator deferiprone at clinical concentrations to inducibly frataxin-deficient HEK-293 cells resulted in chelation of mitochondrial labile iron involved in oxidative stress and in reactivation of iron-depleted aconitase. These led to (1) restoration of impaired mitochondrial membrane and redox potentials, (2) increased adenosine triphosphate production and oxygen consumption, and (3) attenuation of mitochondrial DNA damage and reversal of hypersensitivity to staurosporine-induced apoptosis. Permeant chelators of higher affinity than deferiprone were not as efficient in restoring affected functions. Thus, although iron chelation might protect cells from iron toxicity, rendering the chelated iron bioavailable might underlie the capacity of deferiprone to restore cell functions affected by frataxin deficiency, as also observed in FRDA patients. The siderophore-like properties of deferiprone provide a rational basis for treating diseases of iron misdistribution, such as FRDA, anemia of chronic disease, and X-linked sideroblastic anemia with ataxia.

Unité(s) : Génétique Médicale Pédiatrique, U781

Infantile cortical hyperostosis (Caffey disease): a review

KAMOUN-GOLDRAT A, LE MERRER M

2008 - J. Oral Maxillofac. Surg. 66(10):2145-2150

PURPOSE: Face swelling in infants may have several causes including infantile cortical hyperostosis (Caffey disease), an inflammatory process with swelling of soft tissues and periosteal hyperostosis of some bones. New insights show that this self-limited condition is collagen I-related. PATIENTS AND METHODS: Collagen I is the most important component of bone and dentine. We reviewed literature to lighten this new collagenopathy, the first one with a self-regressive course. RESULTS: After describing a typical case and the clinical and radiologic features of the disease, we discuss the pathogenic pathways and management care for oral professionals. CONCLUSIONS: Oral practitioners could be asked for differential diagnosis. Surgeons could be queried for surgical correction of the bony deformity, especially of facial and mandibular asymmetry.

Unité(s) : Génétique Médicale Pédiatrique

Leber congenital amaurosis: from darkness to spotlight

KAPLAN J

2008 - Ophthalmic Genet. 29(3):92-98

Almost 150 years ago, Theodor Leber described a severe form of vision loss at or near birth which was later given his name. During the century that followed this description, ophthalmologists dedicated efforts to give an accurate definition of the disease but patients were neglected because of the inability of physicians to provide them with treatment. In the 90s, at the time of the Golden Age of Linkage, the first LCA locus was mapped to a human chromosome and shortly after identified as the gene for guanylate cyclase. This discovery was the spark that made the disease emerge from the shadows as illustrated by the flood of LCA genes identified in the following ten-year period. During the same time period, the clinical variability of the disease was rediscovered and an unexpected physiopathological heterogeneity demonstrated. In the beginning of the third millennium, LCA came out definitively from the tunnel to shine under the bright spotlights with the RPE65 gene therapy trial that succeeded to restore vision in a dog model and opened the door to gene therapy trials in humans.

Unité(s) : U781, Génétique Médicale Pédiatrique

Functional analysis of an ADAMTS10 signal peptide mutation in Weill-Marchesani syndrome demonstrates a long-range effect on secretion of the full-length enzyme

KUTZ WE, WANG LW, DAGONEAU N, ODRCIC KJ, CORMIER-DAIRE V, TRABOULSI EI, APTE SS

2008 - Hum. Mutat. 29(12):1425-1434

We report the identification and functional analysis of the first missense ADAMTS10 mutation (c.73G>A; p.Ala25Thr) causing recessive Weill-Marchesani syndrome (WMS). The Ala25 residue affected by the missense mutation is at the -1 position relative to the ADAMTS10 signal peptidase cleavage site. p.Ala25Thr substituted full-length ADAMTS10 showed consistent and significantly diminished secretion in both HEK293F and Cos-1 cells. However, a C-terminally truncated construct lacking the ancillary domain and containing only the signal peptide, the propeptide and the catalytic domain (p.Ala25Thr Pro-Cat) was efficiently secreted in both HEK293F cells and Cos-1 cells. Edman degradation of purified p.Ala25Thr Pro-Cat and p.Ala25Thr substituted full-length ADAMTS10 from HEK293F cells demonstrated correct signal peptide processing. Thus, the p.Ala25Thr substitution hinders secretion of full-length ADAMTS10, but not Pro-Cat from cells, yet permits signal peptide removal. We infer that folding of the complex C-terminal ancillary domain is the rate-limiting step in biosynthesis of ADAMTS10, and that it (but not Pro-Cat) is sensitive to subtle changes in efficiency of signal peptide cleavage. These observations represent an unprecedented effect of a signal peptide mutation and support a model in which the initial cotranslational processing events during protein biosynthesis can have long-range effects on protein folding and secretion.

Unité(s) : Génétique Médicale Pédiatrique, U781

Polymorphisms of coding trinucleotide repeats of homeogenes in neurodevelopmental psychiatric disorders

LAROCHE F, RAMOZ N, LEROY S, FORTIN C, ROUSSELOT-PAILLET B, PHILIPPE A, COLLEAUX L, BRESSON JL, MOGENET A, GOLSE B, MOUREN-SIMEONI MC, GORWOOD P, GALLI T, SIMONNEAU M, KREBS MO, ROBEL L

2008 - Psychiatr. Genet. 18(6):295-301

OBJECTIVES: Autism (MIMmusical sharp209850) and schizophrenia (MIMmusical sharp181500) are both neurodevelopmental psychiatric disorders characterized by a highly genetic component. Homeogenes and forkhead genes encode transcription factors, which have been involved in brain development and cell differentiation. Thus, they are relevant candidate genes for psychiatric disorders. Genetic studies have reported an association between autism and DLX2, HOXA1, EN2, ARX, and FOXP2 genes whereas only three studies of EN2, OTX2, and FOXP2 were performed on schizophrenia. Interestingly, most of these candidate genes contain trinucleotide repeats coding for polyamino acid stretch in which instability can be the cause of neurodevelopmental disorders. Our goal was to identify variations of coding trinucleotide repeats in schizophrenia, autism, and idiopathic mental retardation. METHODS: We screened the coding trinucleotide repeats of OTX1, EN1, DLX2, HOXA1, and FOXP2 genes in populations suffering from schizophrenia (247 patients), autism (98 patients), and idiopathic mental retardation (56 patients), and compared them with control populations (112 super controls and 202 healthy controls). RESULTS: Novel deletions and insertions of coding trinucleotide repeats were found in the DLX2, HOXA1, and FOXP2 genes. Most of these variations were detected in controls and no difference in their distribution was observed between patient and control groups. Two different polymorphisms in FOXP2 were, however, found only in autistic patients and the functional consequences of these variations of repeats have to be characterized and correlated to particular clinical features. CONCLUSION: This study did not identify specific disease risk variants of trinucleotide repeats in OTX1, EN1, DLX2, HOXA1, and FOXP2 candidate genes in neurodevelopmental psychiatric disorders.

Unité(s) : CIC 9303, Génétique Médicale Pédiatrique, U781

Deletion of 5' sequences of the CSB gene provides insight into the pathophysiology of Cockayne syndrome

LAUGEL V, DALLOZ C, STARY A, CORMIER-DAIRE V, DESGUERRE I, RENOUIL M, FOURMAINTRAUX A, VELEZ-CRUZ R, EGLY JM, SARASIN A, DOLLFUS H

2008 - Eur. J. Human Genet. 16(3):320-327

Cockayne syndrome is an autosomal recessive neurodegenerative disorder characterized by a specific defect in the repair of UV-induced DNA lesions. Most cases of Cockayne syndrome are caused by mutations in the CSB gene but the pathophysiological mechanisms are poorly understood. We report the clinical and molecular data of two severely affected Cockayne patients with undetectable CSB protein and mRNA. Both patients showed severe growth failure, microcephaly, mental retardation, congenital cataracts, retinal pigmentary degeneration, photosensitivity and died at the ages of 6 and 8 years. UV irradiation assays demonstrated that both patients had the classical DNA repair defect. Genomic DNA sequencing of the CSB gene showed a homozygous deletion involving non-coding exon 1 and upstream regulatory sequences, but none of the coding exons. Functional complementation using a wild-type CSB expression plasmid fully corrected the DNA repair defect in transfected fibroblasts. Horibata et al recently proposed that all type of CSB mutations result in a defect in UV damage repair that is responsible for the photosensitivity observed in the syndrome, but that only truncated CSB polypeptides generated by nonsense mutations have some additional inhibitory functions in transcription or in oxidative damage repair, which are necessary to lead to the other features of the phenotype. Our patients do not fit the proposed paradigm and new hypotheses are required to account for the pathophysiology of Cockayne syndrome, at the crossroads between DNA repair and transcription.European Journal of Human Genetics (2008) 16, 320-327; doi:10.1038/sj.ejhg.5201991; published online 9 January 2008.

Unité(s) : Génétique Médicale Pédiatrique, Neurologie

ADAMTSL2 mutations in geleophysic dysplasia demonstrate a role for ADAMTS-like proteins in TGF-beta bioavailability regulation

LE GOFF C, MORICE-PICARD F, DAGONEAU N, WANG LW, PERROT C, CROW YJ, BAUER F, FLORI E, PROST-SQUARCIONI C, KRAKOW D, GE G, GREENSPAN DS, BONNET D, LE MERRER M, MUNNICH A, APTE SS, CORMIER-DAIRE V

2008 - Nat. Genet. 40(9):1119-1123

Geleophysic dysplasia is an autosomal recessive disorder characterized by short stature, brachydactyly, thick skin and cardiac valvular anomalies often responsible for an early death. Studying six geleophysic dysplasia families, we first mapped the underlying gene to chromosome 9q34.2 and identified five distinct nonsense and missense mutations in ADAMTSL2 (a disintegrin and metalloproteinase with thrombospondin repeats-like 2), which encodes a secreted glycoprotein of unknown function. Functional studies in HEK293 cells showed that ADAMTSL2 mutations lead to reduced secretion of the mutated proteins, possibly owing to the misfolding of ADAMTSL2. A yeast two-hybrid screen showed that ADAMTSL2 interacts with latent TGF-beta-binding protein 1. In addition, we observed a significant increase in total and active TGF-beta in the culture medium as well as nuclear localization of phosphorylated SMAD2 in fibroblasts from individuals with geleophysic dysplasia. These data suggest that ADAMTSL2 mutations may lead to a dysregulation of TGF-beta signaling and may be the underlying mechanism of geleophysic dysplasia.

Unité(s) : Cardiologie Pédiatrique, Génétique Médicale Pédiatrique, U781

Editorial

LE MERRER M, ORCEL P

2008 - Best Pract. Res. Clin. Rheumatol. 22(1):1-2

Unité(s) : U781, Génétique Médicale Pédiatrique

Confirmation of RAX gene involvement in human anophthalmia

LEQUEUX L, RIO M, VIGOUROUX A, TITEUX M, ETCHEVERS H, MALECAZE F, CHASSAING N, CALVAS P

2008 - Clin. Genet. 74(4):392-395

Microphthalmia and anophthalmia are at the severe end of the spectrum of abnormalities in ocular development. Mutations in several genes have been involved in syndromic and non-syndromic anophthalmia. Previously, RAX recessive mutations were implicated in a single patient with right anophthalmia, left microphthalmia and sclerocornea. In this study, we report the findings of novel compound heterozygous RAX mutations in a child with bilateral anophthalmia. Both mutations are located in exon 3. c.664delT is a frameshifting deletion predicted to introduce a premature stop codon (p.Ser222ArgfsX62), and c.909C>G is a nonsense mutation with similar consequences (p.Tyr303X). This is the second report of a patient with anophthalmia caused by RAX mutations. These findings confirm that RAX plays a major role in the early stages of eye development and is involved in human anophthalmia.

Unité(s) : Génétique Médicale Pédiatrique

Genotype-phenotype correlation in 21 patients with Wolf-Hirschhorn syndrome using high resolution array comparative genome hybridisation (CGH)

MAAS NM, VAN BUGGENHOUT G, HANNES F, THIENPONT B, SANLAVILLE D, KOK K, MIDRO A, ANDRIEUX J, ANDERLID BM, SCHOUMANS J, HORDIJK R, DEVRIENDT K, FRYNS JP, VERMEESCH JR

2008 - J. Med. Genet. 45(2):71-80

BACKGROUND: The Wolf-Hirschhorn syndrome (WHS) is usually caused by terminal deletions of the short arm of chromosome 4 and is phenotypically defined by growth and mental retardation, seizures, and specific craniofacial manifestations. Large variation is observed in phenotypic expression of these features. In order to compare the phenotype with the genotype, we localised the breakpoints of the 4 pter aberrations using a chromosome 4 specific tiling BAC/PAC array. METHODS: In total, DNA from 21 patients was analysed, of which 8 had a cytogenetic visible and 13 a submicroscopic deletion. RESULTS AND CONCLUSION: In addition to classical terminal deletions sized between 1.9 and 30 Mb, we observed the smallest terminal deletion (1.4 Mb) ever reported in a patient with mild WHS stigmata. In addition, we identified and mapped interstitial deletions in four patients. This study positions the genes causing microcephaly, intrauterine and postnatal growth retardation between 0.3 and 1.4 Mb and further refines the regions causing congenital heart disease, cleft lip and/or palate, oligodontia, and hypospadias.

Unité(s) : Génétique Médicale Pédiatrique

Sotos syndrome caused by a paracentric inversion disrupting the NSD1 gene

MALAN V, DE BLOIS MC, PRIEUR M, PERRIER-WAILL MC, HUGUET-NEDJAR C, GEGAS L, TURLEAU C, VEKEMANS M, MUNNICH A, ROMANA SP

2008 - Clin. Genet. 73(1):89-91

Unité(s) : Génétique Médicale Pédiatrique, Histo-Embryologie - Cytogénétique

The danger of small height

MAROTEAUX P

2008 - Archives Pédiatrie 15(9):1381-1382

Unité(s) : Génétique Médicale Pédiatrique

Developmental delay, dysmorphic features, neonatal spontaneous fractures, wrinkled skin, and hepatic failure: a new metabolic syndrome ?

MEGARBANE A, SAMARAS L, CHEDID R, CHOUERY E, CHRETIEN D, CAILLAUD C, ABOU-GHOCH J, JALKH N

2008 - Amer. J. Med. Genet. A 146A(24):3198-3201

We report on a consanguineous Lebanese family where two sibs had an axial hypotonia, developmental delay, hirsutism, large fontanels with delayed closure, and dysmorphic facial features that consist of frontal bossing, prominent eyes, slightly down-slanting palpebral fissures, hypertelorism, telecanthus, long eyelashes, gum hypertrophy, and pointed chin. In addition, they had short neck, abnormal thoracic configuration, wrinkled skin on the hands and abdomen, hepato-splenomegaly and neonatal spontaneous fractures. Their overall health and hepatic function deteriorated every time they had fever. The eldest boy died at the age of 18 months secondary to a hepatic failure. Laboratory exams did not reveal any anomaly except for the hepatic function. Differential diagnoses are discussed and the possibility that we might be reporting on a new metabolic syndrome is raised.

Unité(s) : Génétique Médicale Pédiatrique, U781

Unusual presentation of a severe autosomal recessive anhydrotic ectodermal dysplasia with a novel mutation in the EDAR gene

MEGARBANE H, CLUZEAU C, BODEMER C, FRAITAG S, CHABABI-ATALLAH M, MEGARBANE A, SMAHI A

2008 - Amer. J. Med. Genet. A 146A(20):2657-2662

We report on an 18-year-old woman, born to first-cousin parents, presenting with a severe form of anhydrotic ectodermal dysplasia (EDA/HED). She had sparse hair, absent limb hair, absent sweating, episodes of hyperpyrexia, important hypodontia, and hyperconvex nails. She also showed unusual clinical manifestations such as an absence of breasts, a rudimentary extranumerary areola and nipple on the left side, and marked palmo-plantar hyperkeratosis. Light microscopy of skin biopsies showed orthokeratotic hyperkeratosis and absence of sweat glands. A novel homozygous mutation (IVS9 + 1G > A) in the EDAR gene was identified. This mutation results in a total absence of EDAR transcripts and consequently of the EDAR protein, which likely results in abolition of all ectodysplasin-mediated NF-kappaB signaling. This is the first complete loss-of-function mutation in the EDAR gene reported to date, which may explain the unusual presentation of HED in this patient, enlarging the clinical spectrum linked to the dysfunction of the ectodysplasin mediated NF-kappaB signaling.

Unité(s) : Anatomie Pathologique, Dermatologie, Génétique Médicale Pédiatrique, U781

Long-term follow-up in Stuve-Wiedemann syndrome: a clinical report

MENDES-GASPAR I, SALDANHA T, CABRAL P, VILHENA MM, TUNA M, COSTA C, DAGONEAU N, CORMIER-DAIRE V, HENNEKAM RC

2008 - Amer. J. Med. Genet. A 146A(13):1748-1753

Stuve-Wiedemann syndrome (SWS) is an autosomal recessively inherited disorder that is usually associated with high mortality in the neonatal period. Eleven cases have been published with prolonged survival, the oldest being 16 years. This phenotype is characterized by progressive skeletal anomalies including short stature, severe spinal deformities, bowing of the long bones, contractures and spontaneous fractures, and by neurological features that resemble dysautonomia. Here we report on the natural history of a Portuguese girl from birth till 12 years. The diagnosis was molecularly confirmed by the detection of a homozygous 4 bp deletion (167_170 del TAAC) in exon 3 of LIFR. We compare the findings in this patient to other patients with prolonged survival from the literature.

Unité(s) : Génétique Médicale Pédiatrique, U781

CEMARA: a Web Dynamic Application Within a N-tier Architecture for Rare Diseases

MESSIAEN C, LE MIGNOT L, RATH A, RICHARD JB, DUFOUR E, BEN SAID M, JAIS JP, VERLOES A, LE MERRER M, BODEMER C, BAUJAT G, GERARD-BLANLUET M, BOURDON-LANOY E, SALOMON R, AYME S, LANDAIS P

2008 - Stud. Health Technol. Informat. 136(51-56

Rare diseases include a group of conditions characterized by a prevalence lower than 5 per 10,000 in the community. In France, any rare disease affects less than 30,000 patients and often much less. Three to 4% of children and 6% of the population in Europe are affected. It is a true public health stake since most diseases do not have any curative treatment. In France, the Ministry of Health has initiated a National Rare Diseases Plan. Twenty five out of 132 labelled Reference Centres (RC) decided to share a common Information System named CEMARA. It is dedicated to collect continuous and complete records of all patients presenting with a rare disease, and their follow-up. The main objective of CEMARA is to contribute to the missions of the RC regarding the registration and description of their activities, coordination of the network of their correspondents, organization of the follow-up of rare diseases, and analysis of the epidemiological patterns. A description of CEMARA is provided as well as its cooperation with Orphanet and Genatlas, and a presentation of 11803 current records collected by more than 300 health care professionals belonging to more than 70 sites.

Unité(s) : Biostatistique, Dermatologie, Génétique Médicale Pédiatrique, EA 4067

Mitochondrial respiratory chain complex assembly and function during human fetal development

MINAI L, MARTINOVIC J, CHRETIEN D, DUMEZ F, RAZAVI F, MUNNICH A, ROTIG A

2008 - Mol. Genet. Metab. 94(1):120-126

Oxidative phosphorylation (OXPHOS) deficiency may have early antenatal manifestations, probably related to the time course and/or tissue specificity of the disease gene expression during the embryo-fetal period. This feature hampers a fully reliable prenatal enzymological diagnosis of OXPHOS deficiency. We have studied OXPHOS in various human fetal tissues from 9 to 17 weeks of gestation. We found that the fetal respiratory chain complexes are fully assembled and functional at early stages of development in heart, liver, muscle, brain and kidney. We also observed a marked increase of respiratory chain activities and mitochondria content in postnatal compared to prenatal tissues. However, we were not able to detect obvious modification in the size, composition or activity of the various OXPHOS complexes during the second trimester of pregnancy that could account for the variations we observed in a pathological context. Therefore, we suggest that the time-dependent expression of respiratory chain deficiency either during fetal life or after birth could be related to the differential expression or regulation of the mutant proteins.

Unité(s) : Génétique Médicale Pédiatrique, Histo-Embryologie - Cytogénétique, Obstétrique, U781

CABC1 gene mutations cause ubiquinone deficiency with cerebellar ataxia and seizures

MOLLET J, DELAHODDE A, SERRE V, CHRETIEN D, SCHLEMMER D, LOMBES A, BODDAERT N, DESGUERRE I, DE LONLAY P, DE BAULNY HO, MUNNICH A, ROTIG A

2008 - Amer. J. Hum. Genet. 82(3):623-630

Coenzyme Q(10) (CoQ(10)) plays a pivotal role in oxidative phosphorylation (OXPHOS) in that it distributes electrons between the various dehydrogenases and the cytochrome segments of the respiratory chain. Primary coenzyme Q(10) deficiency represents a clinically heterogeneous condition suggestive of genetic heterogeneity, and several disease genes have been previously identified. The CABC1 gene, also called COQ8 or ADCK3, is the human homolog of the yeast ABC1/COQ8 gene, one of the numerous genes involved in the ubiquinone biosynthesis pathway. The exact function of the Abc1/Coq8 protein is as yet unknown, but this protein is classified as a putative protein kinase. We report here CABC1 gene mutations in four ubiquinone-deficient patients in three distinct families. These patients presented a similar progressive neurological disorder with cerebellar atrophy and seizures. In all cases, enzymological studies pointed to ubiquinone deficiency. CoQ(10) deficiency was confirmed by decreased content of ubiquinone in muscle. Various missense mutations (R213W, G272V, G272D, and E551K) modifying highly conserved amino acids of the protein and a 1 bp frameshift insertion c.[1812_1813insG] were identified. The missense mutations were introduced into the yeast ABC1/COQ8 gene and expressed in a Saccharomyces cerevisiae strain in which the ABC1/COQ8 gene was deleted. All the missense mutations resulted in a respiratory phenotype with no or decreased growth on glycerol medium and a severe reduction in ubiquinone synthesis, demonstrating that these mutations alter the protein function.

Unité(s) : Génétique Médicale Pédiatrique, U781, Neurologie, Radiologie Pédiatrique

Is genetics inhumane ?

MUNNICH A

2008 - J. Med. Genet. 45(10):632-634

Unité(s) : Génétique Médicale Pédiatrique

Casting an eye on the Krebs cycle

MUNNICH A

2008 - Nat. Genet. 40(10):1148-1149

Unité(s) : Génétique Médicale Pédiatrique, U781

Safety and accuracy of 64-slice computed tomography coronary angiography in children after the arterial switch operation for transposition of the great arteries

OU P, CELERMAJER DS, MARINI D, AGNOLETTI G, VOUHE P, BRUNELLE F, LE-QUAN-SANG KH, THALABARD JC, SIDI D, BONNET D

2008 - J Amer Coll Cardiol Cardiovasc Imaging 1(3):331-9

OBJECTIVES: We investigated the accuracy of 64-slice computed tomography (CT) angiography, as compared to invasive angiography, to evaluate reimplanted coronary arteries in children after arterial switch operation (ASO) for transposition of the great arteries (TGA). BACKGROUND: Assessment of the integrity of reimplanted coronary arteries is crucial for long-term outcome after ASO for TGA. Noninvasive tests have limited accuracy for detecting significant coronary lesions, and invasive coronary angiography is usually required in this setting. METHODS: One hundred thirty consecutive children, after ASO for TGA (age 5.6 +/- 1.1 years), underwent conventional invasive coronary angiography and coronary CT angiography using a 64-slice scanner. The ability of CT to detect significant coronary stenoses (>30% diameter reduction) of the coronary ostia and proximal segments, and other abnormalities of the coronary arteries was analyzed by blinded comparison to the invasive coronary angiogram. RESULTS: The CT was fully evaluable in 126 of 130 patients (97%), allowing assessment of ostia and proximal segments of all coronary arteries. The CT correctly detected all 12 patients (9.2%) in whom invasive coronary angiography had identified significant coronary lesions, with a sensitivity, specificity, and negative predictive value of 100%. In addition, CT showed nonsignificant coronary lesions (<30% luminal narrowing) in 6 patients and allowed determination of the underlying reasons for coronary luminal narrowing, such as stretching or compression of the re-implanted coronary arteries caused by their anatomic relationship to the adjacent great vessels. CONCLUSIONS: 64-slice CT coronary angiography performs as well as invasive angiography for detecting significant coronary lesions in the majority of children who have undergone the arterial switch procedure for TGA. CT also provides information on the underlying mechanism of coronary luminal narrowing.

Unité(s) : Cardiologie Pédiatrique, Chirurgie Cardiaque Pédiatrique, Radiologie Pédiatrique, Génétique Médicale Pédiatrique

The regulation of PTC containing transcripts of the human NDUFS4 gene of complex I of respiratory chain and the impact of pathological mutations

PANELLI D, PETRUZZELLA V, VITALE R, DE RASMO D, MUNNICH A, ROTIG A, PAPA S

2008 - Biochimie 90(10):1452-1460

The regulation of alternative transcripts of the NDUFS4 gene of complex I of the respiratory chain has been studied in human cell lines. One of the alternative transcripts (SV1) is subjected to the NMD degradation pathway which involves the hUPF1 and hUPF2 factors. Another transcript (SV3) appears to be controlled in the nuclear fraction and to be enhanced when hUPF1 is depleted, but unaffected by translation inhibitors or when hUPF2 expression is down-regulated. A pathological homozygous nonsense mutation in exon 1, found in a patient affected by mitochondrial disorder, inactivated in the patient's fibroblasts NMD degradation of SV1 and enhanced the nuclear production of SV3. In another patient with a homozygous splice acceptor site mutation in intron 1, SV3, which was the only transcript of NDUFS4 gene to be produced, accumulated in fibroblasts.

Unité(s) : Génétique Médicale Pédiatrique, U793

Neurobehavioral Profile and Brain Imaging Study of the 22q13.3 Deletion Syndrome in Childhood

PHILIPPE A, BODDAERT N, VAIVRE-DOURET L, ROBEL L, DANON-BOILEAU L, MALAN V, DE BLOIS MC, HERON D, COLLEAUX L, GOLSE B, ZILBOVICIUS M, MUNNICH A

2008 - Pediatrics 122(2):e376-e382

OBJECTIVE. The 22q13.3 deletion syndrome (Online Mendelian Inheritance in Man No. 606232) is a neurodevelopmental disorder that includes hypotonia, severely impaired development of speech and language, autistic-like behavior, and minor dysmorphic features. Although the number of reported cases is increasing, the 22q13.3 deletion remains underdiagnosed because of failure in recognizing the clinical phenotype and detecting the 22qter deletion by routine chromosome analyses. Our goal is to contribute to the description of the neurobehavioral phenotype and brain abnormalities of this microdeletional syndrome. METHODS. We assessed neuromotor, sensory, language, communication, and social development and performed cerebral MRI and study of regional cerebral blood flow measured by positron emission tomography in 8 children carrying the 22q13.3 deletion. RESULTS. Despite variability in expression and severity, the children shared a common developmental profile characterized by hypotonia, sleep disorders, and poor response to their environment in early infancy; expressive language deficit contrasting with emergence of social reciprocity from ages approximately 3 to 5 years; sensory processing dysfunction; and neuromotor disorders. Brain MRI findings were normal or showed a thin or morphologically atypical corpus callosum. Positron emission tomography study detected a localized dysfunction of the left temporal polar lobe and amygdala hypoperfusion. CONCLUSIONS. The developmental course of the 22q13.3 deletion syndrome belongs to pervasive developmental disorders but is distinct from autism. An improved description of the natural history of this syndrome should help in recognizing this largely underdiagnosed condition.

Unité(s) : Génétique Médicale Pédiatrique, Pédo-Psychiatrie

Nephrin Mutations Can Cause Childhood-Onset Steroid-Resistant Nephrotic Syndrome

PHILIPPE A, NEVO F, ESQUIVEL EL, REKLAITYTE D, GRIBOUVAL O, TETE MJ, LOIRAT C, DANTAL J, FISCHBACH M, POUTEIL-NOBLE C, DECRAMER S, HOEHNE M, BENZING T, CHARBIT M, NIAUDET P, ANTIGNAC C

2008 - J. Amer. Soc. Nephrol. 19(10):1871-1878

Classically, infants with mutations in NPHS1, which encodes nephrin, present with nephrotic syndrome within the first 3 mo of life (congenital nephrotic syndrome of the Finnish-type), and children with mutations in NPHS2, which encodes podocin, present later with steroid-resistant nephrotic syndrome. Recently, however, NPHS2 mutations have been identified in children with congenital nephrotic syndrome. Whether NPHS1 mutations similarly account for some cases of childhood steroid-resistant nephrotic syndrome is unknown. In this study, 160 patients who belonged to 142 unrelated families and presented with nephrotic syndrome at least 3 mo after birth were screened for NPHS1 variants once mutations in NPHS2 had been excluded. Compound heterozygous NPHS1 mutations were identified in one familial case and nine sporadic cases. Mutations included protein-truncating nonsense and frameshift mutations, as well as splice-site and missense variants. Mutations were classified as "severe" or "mild" using prediction algorithms and functional assays. Most missense variants trafficked normally to the plasma membrane and maintained the ability to form nephrin homodimers and to heterodimerize with NEPH1, suggesting retained function. The presence of at least one "mild" mutation in these patients likely explains the later onset and milder course of disease. These results broaden the spectrum of renal disease related to nephrin mutations.

Unité(s) : Génétique Médicale Pédiatrique, Néphrologie Pédiatrique, U574

A missense mutation in podocin leads to early and severe renal disease in mice

PHILIPPE A, WEBER S, ESQUIVEL EL, HOUBRON C, HAMARD G, RATELADE J, KRIZ W, SCHAEFER F, GUBLER MC, ANTIGNAC C

2008 - Kidney Int. 73(9):1038-1047

Mutations in the NPHS2 gene, encoding podocin, are responsible for familial autosomal recessive and sporadic cases of steroid-resistant nephrotic syndrome. We have successfully generated a mouse model in which the common p.R138Q mutation found in nephrotic patients is expressed in the kidney. Homozygous mice express the mutant protein, which is mislocated to the cytoplasm, along with a portion of the nephrin pool. These mice die within the first month of life, but their survival depends on the genetic background. Albuminuria manifests early and leads to progressive renal insufficiency, characterized histologically by diffuse mesangiolysis and mesangial sclerosis, endothelial lesions along with podocyte abnormalities such as widespread foot process effacement. Gene expression profiling revealed marked differences between these and the podocin-null mice, including significant perturbations of podocyte-expressed genes such as Cd2ap, Vegfa and the transcription factors Lmx1b and Zhx2. Upregulation of Serpine1 and Tgfb1 implicates these as potential mediators of disease progression in these mice. This mouse model of nephrotic syndrome may serve as a valuable tool in studies of in vivo intracellular protein trafficking of podocyte proteins, as well as testing therapeutic modalities aimed at correcting the targeting of mutant proteins.

Unité(s) : Génétique Médicale Pédiatrique, U574

New evidence of a mitochondrial genetic background paradox: impact of the J haplogroup on the A3243G mutation

PIERRON D, ROCHER C, AMATI-BONNEAU P, REYNIER P, MARTIN-NEGRIER ML, ALLOUCHE S, BATANDIER C, DE CAMARET BM, GODINOT C, ROTIG A, FELDMANN D, BELLANNE-CHANTELOT C, ARVEILER B, PENNARUN E, ROSSIGNOL R, CROUZET M, MURAIL P, THORAVAL D, LETELLIER T

2008 - BMC Med. Gen. 9(.):41

BACKGROUND: The A3243G mutation in the tRNALeu gene (UUR), is one of the most common pathogenic mitochondrial DNA (mtDNA) mutations in France, and is associated with highly variable and heterogeneous disease phenotypes. To define the relationships between the A3243G mutation and mtDNA backgrounds, we determined the haplogroup affiliation of 142 unrelated French patients - diagnosed as carriers of the A3243G mutation - by control-region sequencing and RFLP survey of their mtDNAs. RESULTS: The analysis revealed 111 different haplotypes encompassing all European haplogroups, indicating that the 3243 site might be a mutational hot spot. However, contrary to previous findings, we observed a statistically significant underepresentation of the A3243G mutation on haplogroup J in patients (p = 0.01, OR = 0.26, C.I. 95%: 0.08-0.83), suggesting that might be due to a strong negative selection at the embryo or germ line stages. CONCLUSION: Thus, our study supports the existence of mutational hotspot on mtDNA and a "haplogroup J paradox," a haplogroup that may increase the expression of mtDNA pathogenic mutations, but also be beneficial in certain environmental contexts.

Unité(s) : Génétique Médicale Pédiatrique, U781

Prenatal diagnosis of a ring chromosome 14 in a fetus with a severe skeletal dysplasia

QUENUM-MIRAILLET G, MALAN V, MARTINOVIC J, ENCHA-RAZAVI F, ARAL B, TEXIER I, BONNEFONT JP, VEKEMANS M, MORICHON-DELVALLEZ N

2008 - Prenatal Diag. 28(1):69-71

Unité(s) : Génétique Médicale Pédiatrique, Histo-Embryologie - Cytogénétique

Maternal environment interacts with modifier genes to influence progression of nephrotic syndrome

RATELADE J, LAVIN TA, MUDA AO, MORISSET L, MOLLET G, BOYER O, CHEN DS, HENGER A, KRETZLER M, HUBNER N, THERY C, GUBLER MC, MONTAGUTELLI X, ANTIGNAC C, ESQUIVEL EL

2008 - J. Amer. Soc. Nephrol. 19(8):1491-1499

Mutations in the NPHS2 gene, which encodes podocin, are responsible for some cases of sporadic and familial autosomal recessive steroid-resistant nephrotic syndrome. Inter- and intrafamilial variability in the progression of renal disease among patients bearing NPHS2 mutations suggests a potential role for modifier genes. Using a mouse model in which the podocin gene is constitutively inactivated, we sought to identify genetic determinants of the development and progression of renal disease as a result of the nephrotic syndrome. We report that the evolution of renal disease as a result of nephrotic syndrome in Nphs2-null mice depends on genetic background. Furthermore, the maternal environment significantly interacts with genetic determinants to modify survival and progression of renal disease. Quantitative trait locus mapping suggested that these genetic determinants may be encoded for by genes on the distal end of chromosome 3, which are linked to proteinuria, and on the distal end of chromosome 7, which are linked to a composite trait of urea, creatinine, and potassium. These loci demonstrate epistatic interactions with other chromosomal regions, highlighting the complex genetics of renal disease progression. In summary, constitutive inactivation of podocin models the complex interactions between maternal and genetically determined factors on the progression of renal disease as a result of nephrotic syndrome in mice.

Unité(s) : Génétique Médicale Pédiatrique, Néphrologie Pédiatrique, U574

Variable outcome of growth hormone administration in respiratory chain deficiency

ROMANO S, SAMARA D, CROSNIER H, VALAYANNOPOULOS V, POLAK M, CHRETIEN D, ROTIG A, MUNNICH A, BRAUNER R, DE LONLAY P

2008 - Mol. Genet. Metab. 93(2):195-199

Genetic defects of oxidative phosphorylation (OXPHOS) are known to account for a variety of neuromuscular and non-neuromuscular symptoms in childhood, including growth hormone (GH) deficiency. However GH administration for GH deficiency is controversial in OXPHOS deficiencies as GH is a mitosis-stimulator which may increase energy demand for cell proliferation. Here, we report the observation of four unrelated children with OXPHOS deficiency or bearing a mitochondrial DNA rearrangement and growth retardation, who required GH therapy. The first patient had no GH deficiency while the other three had low GH response to test stimulations. The condition of the first two patients quickly deteriorated under GH administration, GH was then stopped and subsequent clinical improvement was noted. In the other two patients, no adverse event was noted but various additional organs were involved following GH administration. In all patients, no benefit was observed concerning growth response as growth speed remained unchanged. These observations question the use of GH as a treatment of growth retardation for patients with OXPHOS deficiency.

Unité(s) : Département de Pédiatrie, Génétique Médicale Pédiatrique, U781

New case of interstitial deletion 12(q15-q21.2) in a girl with facial dysmorphism and mental retardation

SCHLUTH C, GESNY R, BORCK G, REDON R, ABADIE V, KLEINFINGER P, MUNNICH A, LYONNET S, COLLEAUX L

2008 - Amer. J. Med. Genet. A 146A(1):93-96

Interstitial deletions of the long arm of chromosome 12 are rare rearrangements with only 15 cases reported in the literature. The phenotype may include facial dysmorphism, developmental delay, ectodermal abnormalities, cardiac and renal malformations depending on breakpoints' position. Here, we describe a third case of 12(q15-q21.2) deletion ascertained through CGH-array analyses and provide a 5-year follow-up. The patient presented with pre- and postnatal growth retardation, congenital heart defect, developmental delay, and facial dysmorphism changing with age, underlining the importance of long-term follow-up. We compared this new case with previous observations of 12q deletions in order to propose phenotype-karyotype correlations. (c) 2007 Wiley-Liss, Inc.

Unité(s) : Génétique Médicale Pédiatrique, Pédiatrie Générale, U781

Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) robustly detects and distinguishes 11p15 abnormalities associated with overgrowth and growth retardation

SCOTT RH, DOUGLAS J, BASKCOMB L, NYGREN AO, BIRCH JM, COLE TR, CORMIER-DAIRE V, EASTWOOD DM, GARCIA-MINAUR S, LUPUNZINA P, TATTON-BROWN K, BLIEK J, MAHER ER, RAHMAN N

2008 - J. Med. Genet. 45(2):106-113

BACKGROUND: A variety of abnormalities have been demonstrated at chromosome 11p15 in individuals with overgrowth and growth retardation. The identification of these abnormalities is clinically important but often technically difficult. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) is a simple but effective technique able to identify and differentiate methylation and copy number abnormalities, and thus is potentially well suited to the analysis of 11p15. AIMS: To customize and test an MS-MLPA assay capable of detecting and distinguishing the full spectrum of known 11p15 epigenetic and copy number abnormalities associated with overgrowth and growth retardation and to assess its effectiveness as a first line investigation of these abnormalities. METHODS: Five synthetic probe pairs were designed to extend the range of abnormalities detectable with a commercially available MS-MLPA assay. To define the normal values, 75 normal control samples were analysed using the customized assay. The assay was then used to analyse a "test set" of 24 normal and 27 abnormal samples, with data analysed by two independent blinded observers. The status of all abnormal samples was confirmed by a second technique. RESULTS: The MS-MLPA assay gave reproducible, accurate methylation and copy number results in the 126 samples assayed. The blinded observers correctly identified and classified all 51 samples in the test set. CONCLUSIONS: MS-MLPA robustly and sensitively detects and distinguishes epigenetic and copy number abnormalities at 11p15 and is an effective first line investigation of 11p15 in individuals with overgrowth or growth retardation.

Unité(s) : Génétique Médicale Pédiatrique

Late-onset nephropathic cystinosis: clinical presentation, outcome, and genotyping

SERVAIS A, MORINIERE V, GRŸNFELD JP, NO‘L LH, GOUJON JM, CHADEFAUX-VEKEMANS B, ANTIGNAC C

2008 - Clin. J. Amer. Soc. Nephrol. 3(1):27-35

BACKGROUND AND OBJECTIVES: Cystinosis is an autosomal recessive disease characterized by the intralysosomal accumulation of cystine, as a result of a defect in cystine transport across the lysosomal membrane. Three clinical forms have been described on the basis of severity of symptoms and age of onset: infantile cystinosis, characterized by renal proximal tubulopathy and progression to end-stage renal disease before 12 yr of age; juvenile form, with a markedly slower rate of progression; and adult form, with only ocular abnormalities. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Fourteen patients in nine unrelated families with noninfantile cystinosis were studied. Information about clinical outcome, biochemical data, renal histopathologic data, and genotyping was collected. RESULTS: Eight patients had Fanconi syndrome. Proteinuria was present in all patients. Serum creatinine at last follow-up, without specific treatment, ranged between 69 and 450 mumol/L, at an age of 12 to 56 yr. Four patients reached end-stage renal disease by 12 to 28 yr. Renal biopsies, available in four cases, disclosed focal segmental glomerulosclerosis in three and crystals in three. Genetic screening showed that patients were compound heterozygous for mutations in the CTNS gene in four families and homozygous in two families. Patients had at least one "mild" mutation. A single heterozygous mutation was identified in one family and none in two families (only 72% mutations found). CONCLUSION: Renal involvement is heterogeneous in patients with noninfantile cystinosis even within families, and renal disease should be assessed even in families of patients with seemingly isolated ocular forms.

Unité(s) : Néphrologie Adulte, Néphrologie Pédiatrique, Anatomie Pathologique, Génétique Médicale Pédiatrique, Biochimie Métabolique, U574

Hypophosphatasia: molecular testing of 19 prenatal cases and discussion about genetic counseling

SIMON-BOUY B, TAILLANDIER A, FAUVERT D, BRUN-HEATH I, SERRE JL, ARMENGOD CG, BIALER MG, MATHIEU M, COUSIN J, CHITAYAT D, LIEBELT J, FELDMAN B, GERARD-BLANLUET M, KORTGE-JUNG S, KING C, LAIVUORI H, LE MERRER M, MEHTA S, JERN C, SHARIF S, PRIEUR F, GILLESSEN-KAESBACH G, ZANKL A, MORNET E

2008 - Prenatal Diag. 28(11):993-998

OBJECTIVE: We studied hypophosphatasia (HP) mutations in 19 cases prenatally detected by ultrasonography without familial history of HP. We correlated the mutations with the reported ultrasound signs, and discussed genetic counseling with regard to the particular dominantly inherited prenatal benign form of HP. METHOD: The coding sequence of the tissue nonspecific alkaline phosphatase (TNSALP) gene was analyzed by DNA sequencing, and 3D modeling was used to locate the mutated amino acids with regard to the functional domains of TNSALP. RESULTS: Although reported ultrasound signs were heterogeneous, two mutated alleles were found in 18 of the 19 cases studied, indicating recessive transmission of the disease. Functional domains of TNSALP were affected by 74% of missense mutations. In all the cases, including one with only a heterozygous mutation, molecular, biological, and familial data do not corroborate the hypothesis of prenatal benign HP. The mutation c.1133A>T observed in the prenatal benign form of HP and common in USA was not found in this series. CONCLUSION: The results point out the prenatally detectable allelic heterogeneity of HP. The nature of the detected mutations and the evidence of recessive inheritance do not support these cases being affected with prenatal benign HP.

Unité(s) : Génétique Médicale Pédiatrique, U781

Redistribution of accumulated cell iron: a modality of chelation with therapeutic implications

SOHN YS, BREUER W, MUNNICH A, CABANTCHIK ZI

2008 - Blood 111(3):1690-1699

Various pathologies are characterized by the accumulation of toxic iron in cell compartments. In anemia of chronic disease, iron is withheld by macrophages, leaving extracellular fluids iron-depleted. In Friedreich ataxia, iron levels rise in the mitochondria of excitable cells but decrease in the cytosol. We explored the possibility of using deferiprone, a membrane-permeant iron chelator in clinical use, to capture labile iron accumulated in specific organelles of cardiomyocytes and macrophages and convey it to other locations for physiologic reuse. Deferiprone's capacity for shuttling iron between cellular organelles was assessed with organelle-targeted fluorescent iron sensors in conjunction with time-lapse fluorescence microscopy imaging. Deferiprone facilitated transfer of iron from extracellular media into nuclei and mitochondria, from nuclei to mitochondria, from endosomes to nuclei, and from intracellular compartments to extracellular apotransferrin. Furthermore, it mobilized iron from iron-loaded cells and donated it to preerythroid cells for hemoglobin synthesis, both in the presence and in the absence of transferrin. These unique properties of deferiprone underlie mechanistically its capacity to alleviate iron accumulation in dentate nuclei of Friedreich ataxia patients and to donate tissue-chelated iron to plasma transferrin in thalassemia intermedia patients. Deferiprone's shuttling properties could be exploited clinically for treating diseases involving regional iron accumulation.

Unité(s) : U781, Génétique Médicale Pédiatrique

Refinement of 2q and 7p loci in a large multiplex NTD family

STAMM DS, SIEGEL DG, MEHLTRETTER L, CONNELLY JJ, TROTT A, ELLIS N, ZISMANN V, STEPHAN DA, GEORGE TM, VEKEMANS M, ASHLEY-KOCH A, GILBERT JR, GREGORY SG, SPEER MC

2008 - Birth Defects Res. - A/ Clin. & Mol. Teratol. 82(6):441-452

BACKGROUND: NTDs are considered complex disorders that arise from an interaction between genetic and environmental factors. NTD family 8776 is a large multigenerational Caucasian family that provides a unique resource for the genetic analysis of NTDs. Previous linkage analysis using a genome-wide SNP screen in family 8776 with multipoint nonparametric mapping methods identified maximum LOD* scores of approximately 3.0 mapping to 2q33.1-q35 and 7p21.1-pter. METHODS: We ascertained an additional nuclear branch of 8776 and conducted additional linkage analysis, fine mapping, and haplotyping. Expression data from lymphoblast cell lines were used to prioritize candidate genes within the minimum candidate intervals. Genomic copy number changes were evaluated using BAC tiling arrays and subtelomeric fluorescent in situ hybridization probes. RESULTS: Increased evidence for linkage was observed with LOD* scores of approximately 3.3 for both regions. Haplotype analyses narrowed the minimum candidate intervals to a 20.3 Mb region in 2q33.1-q35 between markers rs1050347 and D2S434, and an 8.3 Mb region in 7p21.1-21.3 between a novel marker 7M0547 and rs28177. Within these candidate regions, 16 genes were screened for mutations; however, no obvious causative NTD mutation was identified. Evaluation of chromosomal aberrations using comparative genomic hybridization arrays, subtelomeric fluorescent in situ hybridization, and copy number variant detection techniques within the 2q and 7p regions did not detect any chromosomal abnormalities. CONCLUSIONS: This large NTD family has identified two genomic regions that may harbor NTD susceptibility genes. Ascertainment of another branch of family 8776 and additional fine mapping permitted a 9.1 Mb reduction of the NTD candidate interval on chromosome 7 and 37.3 Mb on chromosome 2 from previously published data. Identification of one or more NTD susceptibility genes in this family could provide insight into genes that may affect other NTD families.

Unité(s) : Génétique Médicale Pédiatrique, U781

Homozygous mutation of the PHOX2B gene in congenital central hypoventilation syndrome (Ondine's Curse

TROCHET D, DE PONTUAL L, ESTEVAO MH, MATHIEU Y, MUNNICH A, FEINGOLD J, GORIDIS C, LYONNET S, AMIEL J

2008 - Hum. Mutat. 29(5):770

Homozygosity for a dominant allele is relatively rare and preferentially observed in communities with high inbreeding. According to the definition of true dominance, similar phenotypes should be observed in patients heterozygous and homozygous for a dominant mutation. However, the homozygous phenotype usually tends to be more severe than the heterozygous one. In these cases, the wild-type and mutant alleles are semi-dominant. Here we report a patient with a Congenital Central Hypoventilation Syndrome (CCHS) phenotype and homozygosity for a PHOX2B gene mutation leading to an alanine expansion shorter than the threshold hitherto observed in CCHS patients with a heterozygous mutation. This observation adds the concept of mutational threshold per se to the discussion about dominant and recessive alleles.

Unité(s) : Génétique Médicale Pédiatrique, U781

PHOX2B Germline and Somatic Mutations in Late-Onset Central Hypoventilation Syndrome

TROCHET D, DE PONTUAL L, STRAUS C, GOZAL D, TRANG H, LANDRIEU P, MUNNICH A, LYONNET S, GAULTIER C, AMIEL J

2008 - Amer. J. Respir. Crit. Care Med. 177(8):906-911

RATIONALE: Late-Onset Central Hypoventilation Syndrome (LO-CHS) is a rare disorder which may manifest as early as infancy or as late as during adulthood. The potential overlap of LO-CHS with Congenital CHS (C-CHS) is under debate, even though both disorders can result from heterozygous PHOX2B gene mutations. OBJECTIVES: To characterize the PHOX2B status in a series of 25 patients with LO-CHS referred from 3 months of age to adulthood. Whenever a PHOX2B mutations was identified, we ascertained its germline or somatic origin in both LO-CHS patients and in 15 parents of C-CHS probands found to harbour a PHOX2B mutation. METHODS: The PHOX2B gene was analyzed by direct DNA sequencing and origin of the mutation evaluated by genescan analysis. RESULTS: We have identified a heterozygous PHOX2B gene mutation in 17/25 LO-CHS patients. The far most frequent mutation results in a germline +5 alanines expansion in the series of 20 alanines (15 cases) that shows incomplete penetrance and variable expressivity possibly resulting from combined environmental and genetic factors. PHOX2B frameshift and missense mutations have also been identified in patients with LO-CHS. Importantly, one parent found to harbour a somatic mosaic for a +8 alanines expansion developed alveolar hypoventilation in his forties. CONCLUSIONS: These data indicate that PHOX2B gene mutations should be systematically examined in any adult with unexplained central hypoventilation and raise the question of the follow-up for apparently healthy parents found to harbour a somatic mosaic for the PHOX2B mutation identified in their child.

Unité(s) : Génétique Médicale Pédiatrique, U781

SIX2 and BMP4 mutations associate with anomalous kidney development

WEBER S, TAYLOR JC, WINYARD P, BAKER KF, SULLIVAN-BROWN J, SCHILD R, KNUPPEL T, ZUROWSKA AM, CALDAS-ALFONSO A, LITWIN M, EMRE S, GHIGGERI GM, BAKKALOGLU A, MEHLS O, ANTIGNAC C, NETWORK E, SCHAEFER F, BURDINE RD

2008 - J. Amer. Soc. Nephrol. 19(5):891-903

Renal hypodysplasia (RHD) is characterized by reduced kidney size and/or maldevelopment of the renal tissue following abnormal organogenesis. Mutations in renal developmental genes have been identified in a subset of affected individuals. Here, we report the first mutations in BMP4 and SIX2 identified in patients with RHD. We detected 3 BMP4 mutations in 5 RHD patients, and 3 SIX2 mutations in 5 different RHD patients. Overexpression assays in zebrafish demonstrated that these mutations affect the function of Bmp4 and Six2 in vivo. Overexpression of zebrafish six2.1 and bmp4 resulted in dorsalization and ventralization, respectively, suggesting opposing roles in mesendoderm formation. When mutant constructs containing the identified human mutations were overexpressed instead, these effects were attenuated. Morpholino knockdown of bmp4 and six2.1 affected glomerulogenesis, suggesting specific roles for these genes in the formation of the pronephros. In summary, these studies implicate conserved roles for Six2 and Bmp4 in the development of the renal system. Defects in these proteins could affect kidney development at multiple stages, leading to the congenital anomalies observed in patients with RHD.

Unité(s) : Génétique Médicale Pédiatrique, U574