Identification of a new locus for autosomal dominant non-syndromic hearing impairment (DFNA7) in a large Norwegian family

Hereditary hearing impairment affects about 1 in 1000 newborns. In mostcases hearing loss is non-syndromic with no other clinical features, whilein other families deafness is associated with specific clinicalabnormalities. Analysis of large families with non-syndromic and syndromicdeafness have been used to identify genes or gene locations that causehearing impairment. The present report describes a large Norwegian familywith autosomal dominant non-syndromic, progressive high tone hearing losswith linkage to 1q21-q23. A maximum LOD score of 7.65 (theta = 0.00) wasobtained with the microsatellite marker D1S196. Analysis of recombinantindividuals maps the deafness gene (DFNA7) to a 22 cM region between D1S104and D1S466. The region contains several attractive candidate genes. Thisreport supports the idea of extensive genetic heterogeneity in hereditaryhearing impairment and represents the first localization of a deafness genein a Norwegian family.