Mapping of DFN2 to Xq22.

Non-syndromic X-linked deafness is a rare form of genetic deafness accounting for a small proportion of all hereditary hearing loss. It is both clinically and genetically heterogeneous and five loci have been described to date but only two of these have been mapped. DFN2 represents a locus for congenital profound sensorineural hearing loss that has yet to be mapped. We describe a four generation family with this phenotype in which female carriers have a mild/moderate hearing loss affecting the high frequencies. The mutant gene has been mapped to Xq22 using polymorphic microsatellite markers. A maximum two point lod score of 2.91 at theta = 0 was observed with a fully informative dinucleotide repeat at COL4A5, and flanking recombinations were observed at DXS990 and DXS1001.