Exome sequencing and genome-wide copy number variant mapping reveal novel associations with sensorineural hereditary hearing loss
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ABSTRACT: Background The genetic diversity of loci and mutations underlying hereditary hearing loss is an active area of investigation. To identify loci associated with predominantly non-syndromic sensorineural hearing loss, we performed exome sequencing of families and of single probands, as well as copy number variation (CNV) mapping in a case-control cohort. Results Analysis of three distinct families revealed several candidate loci in two families and a single strong candidate gene, MYH7B, for hearing loss in one family. MYH7B encodes a Type II myosin, consistent with a role for cytoskeletal proteins in hearing. High-resolution genome-wide CNV analysis of 150 cases and 157 controls revealed deletions in genes known to be involved in hearing (e.g. GJB6, OTOA, and STRC, encoding connexin 30, otoancorin, and stereocilin, respectively), supporting CNV contributions to hearing loss phenotypes. Additionally, a novel region on chromosome 16 containing part of the PDXDC1 gene was found to be frequently deleted in hearing loss patients (OR = 3.91, 95% CI: 1.62-9.40, p = 1.45 x 10-7). Conclusions We conclude that many known as well as novel loci and distinct types of mutations not typically tested in clinical settings can contribute to the etiology of hearing loss. Our study also demonstrates the challenges of exome sequencing and genome-wide CNV mapping for direct clinical application, and illustrates the need for functional and clinical follow-up as well as curated open-access databases.
Project description:Background The genetic diversity of loci and mutations underlying hereditary hearing loss is an active area of investigation. To identify loci associated with predominantly non-syndromic sensorineural hearing loss, we performed exome sequencing of families and of single probands, as well as copy number variation (CNV) mapping in a case-control cohort. Results Analysis of three distinct families revealed several candidate loci in two families and a single strong candidate gene, MYH7B, for hearing loss in one family. MYH7B encodes a Type II myosin, consistent with a role for cytoskeletal proteins in hearing. High-resolution genome-wide CNV analysis of 150 cases and 157 controls revealed deletions in genes known to be involved in hearing (e.g. GJB6, OTOA, and STRC, encoding connexin 30, otoancorin, and stereocilin, respectively), supporting CNV contributions to hearing loss phenotypes. Additionally, a novel region on chromosome 16 containing part of the PDXDC1 gene was found to be frequently deleted in hearing loss patients (OR = 3.91, 95% CI: 1.62-9.40, p = 1.45 x 10-7). Conclusions We conclude that many known as well as novel loci and distinct types of mutations not typically tested in clinical settings can contribute to the etiology of hearing loss. Our study also demonstrates the challenges of exome sequencing and genome-wide CNV mapping for direct clinical application, and illustrates the need for functional and clinical follow-up as well as curated open-access databases. Single replicates of 151 non-syndromic hereditary hearing loss cases and 157 controls with normal hearing were analyzed.
Project description:The GJB6 gene is located just 35 kb telomeric to GJB2 in the so-called nonsyndromic hearing loss and deafness locus 1 (DFNB1). Knock out mouse models confirmed that inner ear expression of their protein products, connexin 30 (Cx30) and connexin 26 (Cx26), is crucial for hearing acquisition and normal development of the organ of Corti, however the coordinated regulation mechanism of Cx26 and Cx30 expression in the cochlea remains unclear. To investigate the mechanism underlying the etiopathogenesis of DFNB1, we used a microRNA (miRNA) and mRNA integrated expression profiling analysis on Cx30 -/- mice, which represent a model for humans in which large deletions in the DFNB1 locus lead to the down-regulation of both connexins and profound deafness.
Project description:The GJB6 gene is located just 35 kb telomeric to GJB2 in the so-called nonsyndromic hearing loss and deafness locus 1 (DFNB1). Knock out mouse models confirmed that inner ear expression of their protein products, connexin 30 (Cx30) and connexin 26 (Cx26), is crucial for hearing acquisition and normal development of the organ of Corti, however the coordinated regulation mechanism of Cx26 and Cx30 expression in the cochlea remains unclear. To investigate the mechanism underlying the etiopathogenesis of DFNB1, we used a microRNA (miRNA) and mRNA integrated expression profiling analysis on Cx30 -/- mice, which represent a model for humans in which large deletions in the DFNB1 locus lead to the down-regulation of both connexins and profound deafness.
Project description:Next-Generation Sequencing techniques (i.e, targeted re-sequencing and whole exome sequencing) have been employed for the study of two Italian patients affected by age-related hearing loss and of an Italian family affected by hereditary hearing loss. Data analysis led to the identification of three variants in SPATC1L, associated with the clinical phenotype.
Project description:Autism spectrum disorders (ASD) are common, heritable neurodevelopmental conditions. The genetic architecture of ASD is complex, requiring large samples to overcome heterogeneity. Here we broaden coverage and sample size relative to other studies of ASD by using Affymetrix 10K single nucleotide polymorphism (SNP) arrays and 1168 families with = 2 affected individuals to perform the largest linkage scan to date, while also analyzing copy number variation (CNV) in these families. Linkage and CNV analyses implicate chromosome 11p12-p13 and neurexins, respectively, amongst other candidate loci. Neurexins team with previously-implicated neuroligins for glutamatergic synaptogenesis, highlighting glutamate-related genes as promising candidates for ASD. Keywords: Autism spectrum disorder, Affymetrix SNP genotyping, linkage analysis, copy number analysis, chromosomal rearrangements.