The objective of this research project is to map and clone genes that are important for the normal development or maintenance of the auditory system. One strategy for identifying some of the genes important for auditory processes is to ascertain large families each with several hearing impaired individuals. Initial contact will be made by family physicians, audiologist, supervisors in schools for the hearing impaired, and directly by the principal investigators during surveys of schools for the deaf and visits with hearing impairment self-help groups. Members of a family will be evaluated by an audiologist, and instances of hearing impairment will be documented and categorized. A clinician would then examine hearing impaired and unaffected members of the family for the presence of other clinical features so as to distinguish between nonsyndromic and syndromic forms of hearing impairment. Pedigrees of these families will be analyzed to determine the mode of inheritance of the hereditary hearing impairment segregating in each family. Families will be ascertained through audiologists and other clinicians, genetics clinics, schools for the hearing impaired and through linguists and medical anthropologists who study unique sign languages and the sociology of communities with a high proportion of hearing impaired individuals. The mutated gene will then be genetically mapped by a linkage or association based strategy, using DNA typing of highly polymorphic genetic markers distributed across the human genome.