Molecular Diagnosis of Hearing Loss

AbstractThis unit discusses an approach to identifying a genetic cause in an individual with nonsyndromic hearing loss. Two protocols are presented, including a full‐gene sequencing assay to identify mutations in theGJB2gene encoding the connexin 26 protein. Mutations in theGJB2gene represent the most common cause of congenital hearing loss. In addition, a protocol to detect the presence of a 342‐kb deletion that includes a portion of theGJB6gene is presented. TheGJB6‐D13S1830 deletion, in homozygosity or in combination with a singleGJB2mutation, causes hearing loss. In addition to the two protocols presented, the Strategic Planning section presents a discussion of a decision‐making process that can be used to begin determining which gene(s) to test for in a patient presenting with nonsyndromic hearing loss. This task can be quite challenging, with the suspected involvement of over 90 genes.