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:Objectives: Despite recent advancements in diagnostic tools, the genomic landscape of hereditary hearing loss remains largely uncharacterized. One strategy to understand genome-wide aberrations includes the analysis of copy number variation that can be mapped using SNP-microarray technology. A growing collection of literature has begun to uncover the importance of copy number variation in hereditary hearing loss. This pilot study underpins a larger effort that involves the stage-wise analysis of hearing loss patients, many of whom have advanced to high-throughput sequencing analysis. Data description: Our data originate from Infinium HumanOmni1-Quad v1.0 SNP-microarrays (Illumina) that provide useful markers for genome-wide association studies and copy number variation analysis. This dataset comprises a cohort of 108 individuals (99 with hearing loss, 9 normal hearing family members) for the purpose of understanding the genetic contribution of copy number variations to hereditary hearing loss.
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.
Project description:Although most disease-causing variants are within coding region of genes, it is now well established that cis-acting regulatory sequences, depending on 3D-chromatin organization, are required for temporal and spatial control of gene expression. Disruptions of such regulatory elements and/or chromatin conformation are likely to play a critical role in human genetic disease. Hence, recurrent monoallelic cases of the most common hereditary type of nonsyndromic hearing loss (i.e. DFNB1) carrying out only one identified pathogenic allele, led to strongly suggest the presence of uncharacterized distal cis-acting elements in the missing allele. Herewith, we study the spatial organization of a large DFNB1 locus encompassing the gap junction protein beta 2 (GJB2) gene, the most frequently mutated gene in this inherited hearing loss, with the chromosome conformation capture carbon copy technology (5C). By combining this approach with functional activity reporter assays and mapping of CCCTC-binding factor (CTCF) along the DFNB1 locus by quantitative real-time PCR chromatin immunoprecipitation, we identify a novel set of cooperating GJB2 cis-acting elements and propose a DFNB1 three-dimensional looping regulation model. A loop chromatin forming, allows bringing closer enhancers to the GJB2 promoter, but also avoids GJB2 silencing with an enhancer-blocking insulator activity.
Project description:The ataxia telangiectasia-mutated (ATM) gene is a moderate-risk breast cancer susceptibility gene; germline loss-of-function variants are found in up to 3% of hereditary breast and ovarian cancer (HBOC) families who undergo genetic testing. So far, no clear molecular features of breast tumors occuring in ATM deleterious variant carriers have been described, but identification of an ATM-associated tumors signature may help patients' management. To characterize hallmarks of ATM-associated tumors, absolute copy number variation and loss of heterozygosity profiles were obtained from the OncoScan SNP array.
Project description:The DNA-binding protein REST forms complexes with histone deacetylases (HDACs) to repress neuronal genes in non-neuronal cells. In differentiating neurons, REST is downregulated predominantly by transcriptional silencing. Here we report that post-transcriptional inactivation of REST by alternative splicing is required for hearing in humans and mice. We show that in the mechanosensory hair cells of the mouse ear, regulated alternative splicing of a frameshift-causing exon into the Rest mRNA is essential for the derepression of many neuronal genes. Heterozygous deletion of this alternative exon of mouse Rest causes hair cell degeneration and deafness, and the HDAC inhibitor SAHA (Vorinostat) rescues the hearing of these mice. In humans, inhibition of the frameshifting splicing event by a novel REST variant is associated with dominantly inherited deafness. Our data reveal the necessity for alternative splicing-dependent regulation of REST in hair cells, and identify a potential treatment for a group of hereditary deafness cases.
Project description:The DNA-binding protein REST forms complexes with histone deacetylases (HDACs) to repress neuronal genes in non-neuronal cells. In differentiating neurons, REST is downregulated predominantly by transcriptional silencing. Here we report that post-transcriptional inactivation of REST by alternative splicing is required for hearing in humans and mice. We show that in the mechanosensory hair cells of the mouse ear, regulated alternative splicing of a frameshift-causing exon into the Rest mRNA is essential for the derepression of many neuronal genes. Heterozygous deletion of this alternative exon of mouse Rest causes hair cell degeneration and deafness, and the HDAC inhibitor SAHA (Vorinostat) rescues the hearing of these mice. In humans, inhibition of the frameshifting splicing event by a novel REST variant is associated with dominantly inherited deafness. Our data reveal the necessity for alternative splicing-dependent regulation of REST in hair cells, and identify a potential treatment for a group of hereditary deafness cases.
Project description:The DNA-binding protein REST forms complexes with histone deacetylases (HDACs) to repress neuronal genes in non-neuronal cells. In differentiating neurons, REST is downregulated predominantly by transcriptional silencing. Here we report that post-transcriptional inactivation of REST by alternative splicing is required for hearing in humans and mice. We show that in the mechanosensory hair cells of the mouse ear, regulated alternative splicing of a frameshift-causing exon into the Rest mRNA is essential for the derepression of many neuronal genes. Heterozygous deletion of this alternative exon of mouse Rest causes hair cell degeneration and deafness, and the HDAC inhibitor SAHA (Vorinostat) rescues the hearing of these mice. In humans, inhibition of the frameshifting splicing event by a novel REST variant is associated with dominantly inherited deafness. Our data reveal the necessity for alternative splicing-dependent regulation of REST in hair cells, and identify a potential treatment for a group of hereditary deafness cases.