Genetique Medicale

Le Touquet – Paris-Plage, France

Genetique Medicale

Le Touquet – Paris-Plage, France
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Poirier K.,University of Paris Descartes | Hubert L.,French Institute of Health and Medical Research | Viot G.,Gynecologie Obstetrique | Rio M.,Genetique Medicale | And 3 more authors.
Human Mutation | Year: 2017

De novo mutations are a frequent cause of disorders related to brain development. We report the results from the screening of two patients diagnosed with intellectual disability (ID) using exome sequencing to identify new causative de novo mutations. Exome sequencing was conducted in two patient-parent trios to identify de novo variants. In silico and expression studies were also performed to evaluate the functional consequences of these variants. The two patients presented developmental delay with minor facial dysmorphy. One of them presented pharmacoresistant myoclonic epilepsy. We identified two de novo splice variants (c.175+2T>G; c.367+2T>C) in the CSNK2B gene encoding the β subunit of the Caseine kinase 2 (CK2). CK2 is a ubiquitously expressed kinase that is present in high levels in brain and it appears to be constitutively active. The mRNA transcripts were abnormal and significantly reduced in affected fibroblasts and most likely produced truncated proteins. Taking into account that mutations in CSNK2A1, encoding the α subunit of CK2, were previously identified in patients with neurodevelopmental disorders and dysmorphic features, our study confirmed that the protein kinase CK2 plays a major role in brain, and showed that CSNK2, encoding the β subunit, is a novel ID gene. This study adds knowledge to the increasingly growing list of causative and candidate genes in ID and epilepsy, and highlights CSNK2B as a new gene for neurodevelopmental disorders. © 2017 Wiley Periodicals, Inc.

Figueres M.-L.,C.H.U Nantes | Linglart A.,Endocrinologie et Diabete de lEnfant | Linglart A.,French Institute of Health and Medical Research | Bienaime F.,University of Paris Descartes | And 6 more authors.
American Journal of Kidney Diseases | Year: 2014

Loss-of-function mutations of CYP24A1, the enzyme that converts the major circulating and active forms of vitamin D to inactive metabolites, recently have been implicated in idiopathic infantile hypercalcemia. Patients with biallelic mutations in CYP24A1 present with severe hypercalcemia and nephrocalcinosis in infancy or hypercalciuria, kidney stones, and nephrocalcinosis in adulthood. We describe a cohort of 7 patients (2 adults, 5 children) presenting with severe hypercalcemia who had homozygous or compound heterozygous mutations in CYP24A1. Acute episodes of hypercalcemia in infancy were the first symptom in 6 of 7 patients; in all patients, symptoms included nephrocalcinosis, hypercalciuria, low parathyroid hormone (PTH) levels, and higher than expected 1,25-dihydroxyvitamin D levels. Longitudinal data suggested that in most patients, periods of increased sunlight exposure tended to correlate with decreases in PTH levels and increases in calcemia and calciuria. Follow-up of the 2 adult patients showed reduced glomerular filtration rate and extrarenal manifestations, including calcic corneal deposits and osteoporosis. Cases of severe PTH-independent hypercalcemia associated with hypercalciuria in infants should prompt genetic analysis of CYP24A1. These patients should be monitored carefully throughout life because they may be at increased risk for developing chronic kidney disease. © 2014 by the National Kidney Foundation, Inc.

PubMed | Pathological Anatomy and Cytology Center, Genetique medicale, Laboratoire Of Reference Pour Le Diagnostic Genetique Des Maladies Rares, Center Hospitalier Sud Francilien and 17 more.
Type: Journal Article | Journal: Prenatal diagnosis | Year: 2015

Conradi-Hnermann-Happle [X-linked dominant chondrodysplasia punctata 2 (CDPX2)] syndrome is a rare X-linked dominant skeletal dysplasia usually lethal in men while affected women show wide clinical heterogeneity. Different EBP mutations have been reported. Severe female cases have rarely been reported, with only six antenatal presentations.To better characterize the phenotype in female fetuses, we included nine antenatally diagnosed cases of women with EBP mutations. All cases were de novo except for two fetuses with an affected mother and one case of germinal mosaicism.The mean age at diagnosis was 22weeks of gestation. The ultrasound features mainly included bone abnormalities: shortening (8/9 cases) and bowing of the long bones (5/9), punctuate epiphysis (7/9) and an irregular aspect of the spine (5/9). Postnatal X-rays and examination showed ichthyosis (8/9) and epiphyseal stippling (9/9), with frequent asymmetric short and bowed long bones. The X-inactivation pattern of the familial case revealed skewed X-inactivation in the mildly symptomatic mother and random X-inactivation in the severe fetal case. Differently affected skin samples of the same fetus revealed different patterns of X-inactivation.Prenatal detection of asymmetric shortening and bowing of the long bones and cartilage stippling should raise the possibility of CPDX2 in female fetuses, especially because the majority of such cases involve de novo mutations.

PubMed | University of Limoges, Genetique Medicale, Otorhinolaryngologie et chirurgie cervico faciale, Endocrinologie et Medecine de la Reproduction and 3 more.
Type: Journal Article | Journal: Human mutation | Year: 2016

Perrault syndrome (PS) is a rare autosomal recessive condition characterized by deafness and gonadic dysgenesis. Recently, mutations in five genes have been identified: C10orf2, CLPP, HARS2, HSD17B4, and LARS2. Probands included are presented with sensorineural deafness associated with gonadic dysgenesis. DNA was sequenced using next-generation sequencing (NGS) with a panel of 35 deafness genes including the five Perrault genes. Exonic variations known as pathogenic mutations or detected with <1% frequency in public databases were extracted and subjected to segregation analysis within each family. Both mutations and low coverage regions were analyzed by Sanger sequencing. Fourteen female index patients were included. The screening in four cases has been extended to four family members presenting with PS phenotype. For four unrelated patients (28.6%), causative mutations were identified: three homozygous mutations in C10orf2, CLPP, and HARS2, and one compound heterozygous mutation in LARS2. Three additional heterozygous mutations in LARS2 and HSD17B4 were found in three independent familial cases. All these missense mutations were verified by Sanger sequencing. Familial segregation analyses confirmed the molecular diagnosis in all cases carrying biallelic mutations. Because of NGS, molecular analysis confirmed the clinical diagnosis of PS in 28.6% of our cohort and four novel mutations were found in four Perrault genes. For the unsolved cases, exome sequencing should be performed to search for a sixth unknown PS gene.

PubMed | Brest University Hospital Center, Unite de consultations externes, Nancy University Hospital Center, Institute Federatif Of Biologie and 20 more.
Type: Journal Article | Journal: European journal of human genetics : EJHG | Year: 2016

Heterozygous COL2A1 variants cause a wide spectrum of skeletal dysplasia termed type II collagenopathies. We assessed the impact of this gene in our French series. A decision tree was applied to select 136 probands (71 Stickler cases, 21 Spondyloepiphyseal dysplasia congenita cases, 11 Kniest dysplasia cases, and 34 other dysplasia cases) before molecular diagnosis by Sanger sequencing. We identified 66 different variants among the 71 positive patients. Among those patients, 18 belonged to multiplex families and 53 were sporadic. Most variants (38/44, 86%) were located in the triple helical domain of the collagen chain and glycine substitutions were mainly observed in severe phenotypes, whereas arginine to cysteine changes were more often encountered in moderate phenotypes. This series of skeletal dysplasia is one of the largest reported so far, adding 44 novel variants (15%) to published data. We have confirmed that about half of our Stickler patients (46%) carried a COL2A1 variant, and that the molecular spectrum was different across the phenotypes. To further address the question of genotype-phenotype correlation, we plan to screen our patients for other candidate genes using a targeted next-generation sequencing approach.

PubMed | Genetique Medicale, Service de Cytogenetique Medicale; CHU Clermont Ferrand, Clermont University, Pole Gyneco Obstetrique Reproduction Humaine and 2 more.
Type: Comparative Study | Journal: Birth defects research. Part A, Clinical and molecular teratology | Year: 2015

The prognosis and early neonatal management of the VACTERL association depend mainly on the severity of malformations ascertained prenatally.Here we reviewed the spectrum of clinical features observed in cases of VACTERL association ascertained prenatally through ultrasound examination but examined at birth and compared them with cases ascertained postnatally.From 1995 to 2011, a total of 19 cases of VACTERL association were observed in our center; 10 were ascertained prenatally and confirmed after birth whereas 9 were ascertained only after birth. The types and frequencies of malformations observed prenatally were as follows: renal malformations (45%), tracheoesophageal fistula (44%), cardiac malformations (20%), vertebral (13%), and limb (11%) defects. Anal atresia was never detected using routine prenatal ultrasound examination.Further studies of fetuses with the VACTERL association are necessary to better delineate the malformations spectrum observed prenatally to improve the early recognition of the VACTERL association.

PubMed | Howard Hughes Medical Institute, Genetique Medicale, Bordeaux University Hospital Center, University of Miami and 17 more.
Type: | Journal: American journal of human genetics | Year: 2017

Degradation of proteins by the ubiquitin-proteasome system (UPS) is an essential biological process in the development of eukaryotic organisms. Dysregulation of this mechanism leads to numerous human neurodegenerative or neurodevelopmental disorders. Through a multi-center collaboration, we identified six de novo genomic deletions and four de novo point mutations involving PSMD12, encoding the non-ATPase subunit PSMD12 (aka RPN5) of the 19S regulator of 26S proteasome complex, in unrelated individuals with intellectual disability, congenital malformations, ophthalmologic anomalies, feeding difficulties, deafness, and subtle dysmorphic facial features. We observed reduced PSMD12 levels and an accumulation of ubiquitinated proteins without any impairment of proteasome catalytic activity. Our PSMD12 loss-of-function zebrafish CRISPR/Cas9 model exhibited microcephaly, decreased convolution of the renal tubules, and abnormal craniofacial morphology. Our data support the biological importance of PSMD12 as a scaffolding subunit in proteasome function during development and neurogenesis in particular; they enable the definition of a neurodevelopmental disorder due to PSMD12 variants, expanding the phenotypic spectrum of UPS-dependent disorders.

PubMed | Sainte Justine Research Center, University of California at Irvine, Carle Physician Group, Verona Pediatrics and 10 more.
Type: Journal Article | Journal: Human mutation | Year: 2016

Retinoic acid (RA) signaling plays a key role in the development and function of several systems in mammals. We previously discovered that the de novo mutations c.1159C>T (p.Arg387Cys) and c.1159C>A (p.Arg387Ser) in the RA Receptor Beta (RARB) gene cause microphthalmia and diaphragmatic hernia. However, the natural history of affected subjects beyond the prenatal or neonatal period was unknown. Here, we describe nine additional subjects with microphthalmia who have de novo mutations in RARB, including the previously described p.Arg387Cys as well as the novel c.887G>C (p.Gly296Ala) and c.638T>C (p.Leu213Pro). Moreover, we review the information on four previously reported cases. All subjects who survived the neonatal period (n = 10) displayed severe global developmental delay with progressive motor impairment due to spasticity and/or dystonia (with or without chorea). The majority of subjects also showed Chiari type I malformation and severe feeding difficulties. We previously found that p.Arg387Cys and p.Arg387Ser induce a gain-of-function. We show here that the p.Gly296Ala and p.Leu213Pro RARB mutations further promote the RA ligand-induced transcriptional activity by twofold to threefold over the wild-type receptor, also indicating a gain-of-function mechanism. These observations suggest that precise regulation of RA signaling is required for brain development and/or function in humans.

PubMed | SUNY Upstate Medical University, Baylor College of Medicine, Angers University Hospital Center, Tohoku University and 9 more.
Type: Journal Article | Journal: Human mutation | Year: 2016

A rare syndromic form of intellectual disability with impaired speech was recently found associated with mutations in CHAMP1 (chromosome alignment-maintaining phosphoprotein 1), the protein product of which is directly involved in microtubule-kinetochore attachment. Through whole-exome sequencing in six unrelated nonconsanguineous families having a sporadic case of intellectual disability, we identified six novel de novo truncating mutations in CHAMP1: c.1880C>G p.(Ser627*), c.1489C>T; p.(Arg497*), c.1876_1877delAG; p.(Ser626Leufs*4), c.1043G>A; p.(Trp348*), c.1002G>A; p.(Trp334*), and c.958_959delCC; p.(Pro320*). Our clinical observations confirm the phenotypic homogeneity of the syndrome, which represents therefore a distinct clinical entity. Besides, our functional studies show that CHAMP1 protein variants are delocalized from chromatin and are unable to bind to two of its direct partners, POGZ and HP1. These data suggest a pathogenic mechanism of the CHAMP1-associated intellectual disability syndrome mediated by direct interacting partners of CHAMP1, several of which are involved in chromo/kinetochore-related disorders.

Srour M.,University of Montréal | Chitayat D.,Mount Sinai Hospital | Chitayat D.,Hospital for Sick Children | Caron V.,University of Montréal | And 16 more authors.
American Journal of Human Genetics | Year: 2013

Anophthalmia and/or microphthalmia, pulmonary hypoplasia, diaphragmatic hernia, and cardiac defects are the main features of PDAC syndrome. Recessive mutations in STRA6, encoding a membrane receptor for the retinol-binding protein, have been identified in some cases with PDAC syndrome, although many cases have remained unexplained. Using whole-exome sequencing, we found that two PDAC-syndrome-affected siblings, but not their unaffected sibling, were compound heterozygous for nonsense (c.355C>T [p.Arg119*]) and frameshift (c.1201-1202insCT [p.Ile403Serfs*15]) mutations in retinoic acid receptor beta (RARB). Transfection studies showed that p.Arg119* and p.Ile403Serfs*15 altered RARB had no transcriptional activity in response to ligands, confirming that the mutations induced a loss of function. We then sequenced RARB in 15 subjects with anophthalmia and/or microphthalmia and at least one other feature of PDAC syndrome. Surprisingly, three unrelated subjects with microphthalmia and diaphragmatic hernia showed de novo missense mutations affecting the same codon; two of the subjects had the c.1159C>T (Arg387Cys) mutation, whereas the other one carried the c.1159C>A (p.Arg387Ser) mutation. We found that compared to the wild-type receptor, p.Arg387Ser and p.Arg387Cys altered RARB induced a 2- to 3-fold increase in transcriptional activity in response to retinoic acid ligands, suggesting a gain-of-function mechanism. Our study thus suggests that both recessive and dominant mutations in RARB cause anophthalmia and/or microphthalmia and diaphragmatic hernia, providing further evidence of the crucial role of the retinoic acid pathway during eye development and organogenesis. © 2013 The American Society of Human Genetics. All rights reserved.

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