This article is a review of the genes and
genetic disorders that affect hearing in humans and a few selected mouse models of
deafness. Genetics is playing an increasingly critical role in the practice of medicine. This is not only in part to the importance that genetic knowledge has on traditional
genetic diseases but also in part to the fact that genetic knowledge provides an understanding of the fundamental biological process of most diseases. The
proteins coded by the genes related to
hearing loss (HL) are involved in many functions in the ear, such as cochlear fluid homeostasis,
ionic channels, stereocilia morphology and function, synaptic transmission, gene regulation, and others. Mouse models play a crucial role in understanding of the pathogenesis associated with these genes. Different types of familial HL have been recognized for years; however, in the last two decades, there has been tremendous progress in the discovery of gene mutations that cause
deafness. Most of the cases of genetic
deafness recognized today are monogenic disorders that can be broadly classified by the mode of inheritance (i.e., autosomal dominant, autosomal recessive, X-linked, and mitochondrial inheritance) and by the presence of associated phenotypic features (i.e., syndromic; and nonsyndromic). In terms of nonsyndromic HL, the chromosomal locations are currently known for ∼ 125 loci (54 for dominant and 71 for recessive
deafness), 64 genes have been identified (24 for dominant and 40 for recessive
deafness), and there are many more loci for syndromic
deafness and X-linked and
mitochondrial DNA disorders (http://hereditaryhearingloss.org). Thus, today's clinician must understand the science of medical genetics as this knowledge can lead to more effective disease diagnosis, counseling, treatment, and prevention.