A GENE FOR WAARDENBURG SYNDROME TYPE-2 MAPS CLOSE TO THE HUMAN HOMOLOG OF THE MICROPHTHALMIA GENE AT CHROMOSOME 3P12-P14.1

Waardenburg syndrome (WS), an autosomal dominant syndrome of hearing loss and pigmentary disturbances, comprises at least two separate conditions. WS type 1 is normally caused by mutations in PAX3 located at chromosome 2q35 and is distinguished clinically by minor facial malformations. We have now located a gene for WS type 2. Two families show linkage to a group of microsatellite markers located on chromosome 3p12-p14.1. D3S1261 gave a maximum lod score of 6.5 at zero recombination in one large Type 2 family. in a second, smaller family the adjacent marker D3S1210 gave a lod of 2.05 at zero recombination. interestingly the human homologue (MITF) of the mouse microphthalmia gene, a good candidate at the phenotypic level, has recently been mapped to 3p12.3-p14.4.