Hearing loss is the most common sensory disorder in humans, and genetic factors are a major cause. Approximately 15-20% of genetic cases exhibit an autosomal dominant pattern of transmission. So far, 41 autosomal dominant loci have been mapped and 17 genes have been identified. Here we report the mapping of a novel locus for autosomal dominant non-syndromic hearing loss, DFNA47, to chromosome 9p21-22 in a large multigenerational Italian family with progressive hearing impairment. Most affected individuals noticed hearing impairment after their teens with subsequent gradual progression to a moderate-severe loss. There were no obvious vestibular dysfunction and other associated abnormalities. A maximum lod score of 3.14 was obtained with marker D9S157 (at θ=0) after a genome wide search. The study of additional markers allowed us to confirm this region with positive lod scores of 3.58 (at θ=0 from D9S285) and of 3.67 (at θ=0 from D9S162). Recombinants define a region of approximately 9 cM flanked by markers D9S268 and D9S942. Multipoint linkage analysis showed a Lod score of 4.26. Few known genes map to the region, and those possibly related by function to hearing are being screened for disease-causing mutations.
- Autosomal dominant nonsyndromic hearing loss
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