Project Summary Recent advances in molecular technologies have enhanced our ability to identify genetic forms of hearing losses with several important consequences. First, the incorporation of genetic testing into diagnostic algorithms has improved clinical care for deaf/hard-of-hearing persons. As more deafness-associated genes are identified and incorporated into these panels, further improvements in clinical care will follow. Second, because the genetic spectrum of non-syndromic hearing loss (NSHL) has been better defined, epidemiological studies of genetic deafness are possible. These studies can be used to define knowledge gaps in our understanding of genetic hearing loss. Third, the identification of genes required for normal auditory function provides insight into inner ear physiology at the molecular level. This insight is foundational to the development of novel therapies to treat deafness. During the 09/01/2014-08/31/2019 grant period, we built on prior successes to advance our understanding of NSHL by focusing on two specific aims. • Specific Aim 1: To identify genetic variants in regulatory elements of deafness-associated genes that contribute to NSHL • Specific Aim 2. To compare simple and complex haplotypes in two well-defined populations – one with age-related hearing loss (ARHL) and one with normal hearing – to identify whether common variants in deafness-associated genes contribute to ARHL In this competitive renewal, our overarching goals are to further improve the clinical care of persons with hearing loss and provide a more robust foundation for therapies that target specific types of genetic hearing loss. We will achieve these goals by addressing current knowledge gaps as reflected in the following specific aims: • Specific Aim 1: We will identify novel deafness-associated genes Hypothesis: By leveraging whole genome sequencing and structured bioinformatic analyses in carefully selected cohorts, we will optimize our ability to identify novel deafness-associated genes. The role of these genes in the biology of hearing and deafness will be validated using animals models of hearing loss. • Specific Aim 2: We will resolve hidden heritability and complexity in known deafness- associated genes Hypothesis: A wealth of unidentified and unrecognized complexity lies at the variant level in known deafness-associated genes. Examples include the unrecognized effect of missense variants of low predicted pathogenicity, the pathogenicity of synonymous variants, and the pathogenicity of non-coding variants. The completion of these aims will refine our understanding of the biology of hearing and deafness, improve clinical care for persons with hearing loss, provide a better genetic foundation for precision medicine for the hearing impaired, and identify new targets for gene therapy for deafness.