MAPPING OF DFN2 TO XQ22

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