ABSTRACT
The autosomal recessive demyelinating form of Charcot-Marie-Tooth can be due to SH3TC2 gene pathogenic variants (CMT4C, AR-CMTde-SH3TC2). We report on a series of 13 patients with AR-CMTde-SH3TC2 among a French cohort of 350 patients suffering from all type of inheritance peripheral neuropathy. The SH3TC2 gene appeared to be the most frequently mutated gene for demyelinating neuropathy in this series by NGS. Four new pathogenic variants have been identified: two nonsense variants (p.(Tyr970*), p.(Trp1199*)) and two missense variants (p.(Leu1126Pro), p.(Ala1206Asp)). The recurrent variant p.Arg954* was present in 62%, and seems to be a founder mutation. The phenotype is fairly homogeneous, as all these patients, except the youngest ones, presented scoliosis and/or hearing loss.
Subject(s)
Charcot-Marie-Tooth Disease/genetics , Deafness/genetics , Genetic Variation/genetics , Intracellular Signaling Peptides and Proteins/genetics , Scoliosis/genetics , Adult , Aged , Charcot-Marie-Tooth Disease/epidemiology , Child , Cohort Studies , Deafness/epidemiology , Female , France/epidemiology , Humans , Male , Middle Aged , Mutation/genetics , Scoliosis/epidemiology , Young AdultABSTRACT
Although whole-exome sequencing (WES) is the gold standard for the diagnosis of neurodevelopmental disorders (NDDs), it remains expensive for some genetic centers. Commercialized panels comprising all OMIM-referenced genes called "medical exome" (ME) constitute an alternative strategy to WES, but its efficiency is poorly known. In this study, we report the experience of 2 clinical genetic centers using ME for diagnosis of NDDs. We recruited 216 consecutive index patients with NDDs in 2 French genetic centers, corresponded to the daily practice of the units and included non-syndromic intellectual disability (NSID, n = 33), syndromic ID (NSID = 122), pediatric neurodegenerative disorders (n = 7) and autism spectrum disorder (ASD, n = 54). We sequenced samples from probands and their parents (when available) with the Illumina TruSight One sequencing kit. We found pathogenic or likely pathogenic variants in 56 index patients, for a global diagnostic yield of 25.9%. The diagnosis yield was higher in patients with ID as the main diagnosis (32%) than in patients with ASD (3.7%). Our results suggest that the use of ME is a valuable strategy for patients with ID when WES cannot be used as a routine diagnosis tool.
Subject(s)
Exome Sequencing , Genetic Association Studies , Genetic Predisposition to Disease , Neurodevelopmental Disorders/genetics , Adolescent , Adult , Alleles , Child , Child, Preschool , Computational Biology/methods , Female , Genetic Association Studies/methods , Humans , Infant , Inheritance Patterns , Male , Middle Aged , Neurodevelopmental Disorders/diagnosis , Phenotype , Sequence Analysis, DNA/methods , Young AdultABSTRACT
Rhombencephalosynapsis is an uncommon, but increasingly recognized, cerebellar malformation defined as vermian agenesis with fusion of the hemispheres. The embryologic and genetic mechanisms involved are still unknown, and to date, no animal models are available. In the present study, we used Agilent oligonucleotide arrays in a large series of 57 affected patients to detect candidate genes. Four different unbalanced rearrangements were detected: a 16p11.2 deletion, a 14q12q21.2 deletion, an unbalanced translocation t(2p;10q), and a 16p13.11 microdeletion containing 2 candidate genes. These genes were further investigated by sequencing and in situ hybridization. This first microarray screening of a rhombencephalosynapsis series suggests that there may be heterogeneous genetic causes.