Deafness and Hereditary Hearing Loss Overview

Summary Disease characteristics. Several hundred genes are known to cause hereditary hearing loss and deafness. The hearing loss may be conductive, sensorineural, or a combination of both; syndromic or nonsyndromic; and prelingual (before language develops) or postlingual (after language develops). Diagnosis/testing. Genetic forms of hearing loss must be distinguished from acquired (non-genetic) causes of hearing loss. The genetic forms of hearing loss are diagnosed by otologic, audiologic, and physical examination, family history, ancillary testing (such as CT examination of the temporal bone), and molecular genetic testing. Molecular genetic tests are available for many types of syndromic and nonsyndromic deafness, often only on a research basis. On a clinical basis, molecular genetic testing is available for the diagnosis of branchiootorenal (BOR) syndrome (EYA1 gene), Mohr-Tranebjaerg syndrome (deafnessdystonia-optic atrophy syndrome; TIMM8A gene), Pendred syndrome (SLC26A4 gene), Usher syndrome type 2A (USH2A gene), Usher syndrome type 3 (one mutation in USH3A), DFNA3 and DFNB1 (GJB2 and GJB6 genes), DFN3 (POU3F4 gene), DFNB4 (SLC26A4 gene), DFNA6/14 (WFS1 gene), DFNA8/12, DFNB9 (OTOF gene), and DFNB21 (TECTA gene). Testing for deafness-causing mutations in the GJB2 gene (which encodes the protein connexin 26) and GJB6 (which encodes the protein connexin 30) plays a prominent role in diagnosis and genetic counseling. Management. Hereditary hearing loss is managed by a team including an otolaryngologist, an audiologist, a clinical geneticist, and a pediatrician, and sometimes an educator of the Deaf, a neurologist, and a pediatric ophthalmologist. Treatment includes hearing aids and vibrotactile devices; cochlear implantation is considered in children over