A novel locus for autosomal recessive nonsyndromic hearing impairment, DFNB63, maps to chromosome 11q13.2-q13.4.

Hereditary hearing impairment is a genetically heterogeneous disorder. To date, 49 autosomal recessive nonsyndromic hearing impairment (ARNSHI) loci have been described, and there are more than 16 additional loci announced. In 25 of the known loci, causative genes have been identified. A genome scan and fine mapping revealed a novel locus for ARNSHI (DFNB63) on chromosome 11q13.2-q13.4 in a five-generation Turkish family (TR57). The homozygous linkage interval is flanked by the markers D11S1337 and D11S2371 and spans a 5.3-Mb interval. A maximum two-point log of odds score of 6.27 at a recombination fraction of theta = 0.0 was calculated for the marker D11S4139. DFNB63 represents the eighth ARNSHI locus mapped to chromosome 11, and about 3.33 Mb separate the DFNB63 region from MYO7A (DFNB2/DFNB11). Sequencing of coding regions and exon-intron boundaries of 13 candidate genes, namely SHANK2, CTTN, TPCN2, FGF3, FGF4, FGF19, FCHSD2, PHR1, TMEM16A, RAB6A, MYEOV, P2RY2 and KIAA0280, in genomic DNA from an affected individual of family TR57 revealed no disease-causing mutations.