Further evidence for a third deafness gene within the DFNA2 locus

DFNA2 is a complex locus. Two hearing loss genes have been identified at this site: GJB3, the gene that encodes the gap junction protein connexin 31, and KCNQ4, a voltage-gated potassium channel gene. A third gene has previously been postulated to explain the hearing loss in an Indonesian family linked to the region but devoid of mutation in either known gene (Van Hauwe et al. [1999: Nat Genet 21:263]). We have identified a large five-generation family with nonsyndromic, autosomal dominant progressive high-frequency hearing loss. The hearing impairment maps to 1p34, the site of the DFNA2 locus. Two-point linkage analysis of microsatellite markers spanning the locus resulted in a lod score of 6.6 at D1S391 at theta = 0. We have investigated both identified deafness genes in affected and unaffected family members and have not found any disease-causing mutations, suggesting that another hearing impairment gene resides at the DFNA2 locus.