A novel autosomal recessive non-syndromic hearing impairment locus (DFNB47) maps to chromosome 2p25.1-p24.3

Hereditary hearing impairment (HI) displays extensive genetic heterogeneity. Autosomal recessive (AR) forms of prelingual HI account for approximately 75% of cases with a genetic etiology. A novel AR non-syndromic HI locus (DFNB47) was mapped to chromosome 2p25.1-p24.3, in two distantly related Pakistani kindreds. Genome scan and fine mapping were carried out using microsatellite markers. Multipoint linkage analysis resulted in a maximum LOD score of 4.7 at markers D2S1400 and D2S262. The three-unit support interval was bounded by D2S330 and D2S131. The region of homozygosity was found within the three-unit support interval and flanked by markers D2S2952 and D2S131, which corresponds to 13.2 cM according to the Rutgers combined linkage-physical map. This region contains 5.3 Mb according to the sequence-based physical map. Three candidate genes, KCNF1, ID2 and ATP6V1C2 were sequenced, and were found to be negative for functional sequence variants.