Nonsyndromic hearing loss caused by USH1G mutations: widening the USH1G disease spectrum.

Abstract

Currently, six genes are known to be associated with Usher syndrome type I, and mutations in most of these genes can also cause nonsyndromic hearing loss. The one exception is USH1G, which is currently only known to be involved in Usher syndrome type I and atypical Usher syndrome. A Dutch family with autosomal recessively inherited hearing loss was examined. Audiometric, ophthalmic, and vestibular evaluations were performed besides the genetic analysis. The hearing loss had an early onset with a downsloping audiogram configuration. Slight progression of the hearing loss was seen in both affected individuals. Compound heterozygous mutations in USH1G were found to segregate with the hearing loss in this family, a missense (c.310A>G, p.Met104Val) and a frameshift mutation (c.780insGCAC, p.Tyr261Alafs*96). Extensive ophthalmic and vestibular examinations demonstrated no abnormalities that are usually associated with Usher syndrome type I. This is the first family presented with nonsyndromic hearing loss caused by mutations in USH1G. Our findings expand the phenotypic spectrum of mutations in USH1G.