Single gene mutations are the most common cause of nonsyndromic deafness, which, in turn, is the most frequent cause of severe-to-profound sensorineural hearing loss (SNHL) in early childhood. Identification of such genes and their products is important for the clinical identification of carriers of hearing loss, the confirmation of a diagnosis of genetic SNHL in deaf children who have no stigmata of associated syndromes or history of congenital infection or meningitis, and for the elucidation of the biology of auditory function at a molecular level. "Syndromic deafness" affects the minority of hearing impaired individuals who have some recognizable set of physical features associated with hearing loss. Syndromes involving deafness often have a genetic basis; Turner syndrome has a chromosomal basis.

We characterized the rate and type of hearing loss that exists in Turner syndrome and used PCR of polymorphic microsatellite DNA to show the lack of correlation between the parental origin of the retained X chromosome and hearing status in a Turner syndrome population. It is postulated that the presence of unpaired genes on the X chromosome may account for hearing loss and other phenotypic abnormalities in this syndrome.

We chose the mouse as a model to facilitate genetic work and provide possible correlation with future human mapping. Currently, we use molecular biology techniques to identify candidate genes for deafness, i.e., total RNA is isolated from neonatal mouse cochlea and complementary DNA from messenger RNAs that are amplified and cloned. Additionally, degenerate primers are designed from conserved sequences of genes coding for proteins that can be rationally postulated to serve a physiologic role in audition.