[Genetic aspects of deafness].

Congenital sensorineural hearing impairment affects approximately 1 in 1000-2000 children and is of genetic origin in at least one half of these cases. Over 70% of congenital sensorineural hearing impairment is non-syndromic while, about 30% is associated with other defects. Over 75% of congenital non-syndromic hearing sensorineural hearing impairment is autosomal recessive and to date at lest ten loci have been implicated. The remaining forms are transmitted in an autosomal dominant, or X-linked (2%) manner. Some congenital types of hearing impairment are also due to chromosomal aneuploides or mitochondrial DNA mutations. Although different loci associated with hearing impairment have been mapped to specific chromosomic regions, the cloning and the functional characterization of these genes is not immediate.