A novel locus DFNA 26 maps to chromosome 17q25 in two unrelated families with progressive autosomal dominant hearing loss. T. Yang, R. Smith. Genetics PhD Program, The University of Iowa, Iowa City, IA.
   It is estimated that 15-25% of hereditary hearing loss has an autosomal dominant mode of inheritance. To date, 31 autosomal dominant loci have been mapped, and 11 of the associated genes, with diverse functions, have been cloned. We have mapped a novel locus for autosomal dominant non-syndromic hearing loss, DFNA26, to chromosome 17q25 in two unrelated American families with progressive autosomal dominant hearing loss. Two-point linkage analysis generates a maximum lod score of 3.20 and 5.06 for each family. Because the genetic map of this region is not completely consistent, we have used radiation hybrid mapping to establish marker order. We also have refined the candidate DFNA26 gene region by identifying new short tandem repeat polymorphisms (STRPs) and single nucleotide polymorphisms (SNPs). The former were identified by pulling out sequenced BACs using mapped ESTs; the latter were identified by SSCP analysis of STSs. Numerous genes are known to map to the region, and among the positional candidate genes, those functionally related to hearing are being screened for deafness-causing mutations.