Identification of Autosomal Recessive Nonsyndromic Hearing Impairment Genes

Baylor College Of Medicine, Houston TX

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Abstract

DESCRIPTION (provided by applicant): Identification of Autosomal Recessive Non-syndromic Hearing Impairment Genes Non-syndromic hearing impairment (NSHI) is the most heterogeneous trait known, with >150 mapped loci and >70 identified genes. However, the vast majority of NSHI genes have neither been localized nor identified. The extreme genetic heterogeneity of NSHI is due to the different processes which can malfunction within the inner ear and cause the hearing impairment (HI) phenotype. For autosomal recessive (AR) NSHI usually only consanguineous pedigrees are sufficiently large enough to map and identify novel genes. Therefore the Pakistani population is ideal to identify ARNSHI genes due to the high rates of consanguinity. To date we have ascertained 445 Pakistani families with ARNSHI which have undergone a genome scan and linkage analysis. We are continuing to ascertain ARNSHI families and localize NSHI genes. Thus far we have identified the NSHI gene for 173 of these families and 156 families map to a region containing a known gene. Of the 116 families for which the gene has not been identified and there is no known gene within the linkage region, 22 families have established linkage (LOD score >3.3) to 19 unique genomic regions, 53 families display strongly suggestive linkage (2.0<LOD score<3.3) and 41 families display suggestive linkage (1.5<LOD score<2.0). Gene identification will be performed using exome and whole genome next generation sequencing. We will begin by sequencing a DNA sample from an HI pedigree member from those families which established linkage and then sequence samples from families with suggestive linkage. Once a putative novel NSHI gene has been identified, segregation within the family will be verified and also ethnically matched controls will be sequenced to ensure that the variant is not present. Additionally, the identified NSHI genes will be followed up in additional families which are linked to the same region in our collection as well as in ARNSHI families from our longtime collaborators. These additional families will not only facilitate finding additional causal variants but can potentially allow for identification of variats within other populations including Middle Eastern, European and African American. Goal: To identify novel autosomal recessive non-syndromic hearing impairment genes using next generation sequencing.