ABSTRACT
Approximately 1 in 1000 children is affected sporadically with congenital or early childhood-onset sensorineural hearing impairment/deafness. Approximately 50% have a genetic cause, with 70% nonsyndromal and 75% attributable to a mutation in an autosomal recessive gene. Studies of the recurrence of hearing impairment in the offspring of couples, both of whom have hearing impairment/deafness, have indicated that up to 100 genes are responsible for nonsyndromal sensorineural hearing impairment/deafness (NSSNHI/D). During the past 8 years, 28 autosomal recessive, 30 autosomal dominant, and 5 X-linked loci have been mapped; during the past 3 years, 6 autosomal recessive, 10 autosomal dominant, and 2 X-linked genes for NSSNHI/D have been cloned. It is now possible to offer mutation testing of children sporadically affected with NSSNHI/D to determine whether their hearing impairment is attributable to a genetic cause allowing precise Mendelian recurrence risk advice to be provided for couples in whom a mutation is identified.
KEYWORD
Hearing impairment - inheritance - molecular genetics
