OCA4: evidence for a founder effect for the p.D157N mutation of the MATP gene in Japanese and Korean.

Oculocutaneous albinism type 4 (OCA4) was identified as a rare form of human OCA among a group of autosomal recessive hypopigmentary disorders. Little is known about the prevailing distribution of patients of OCA4 with mutations of the MATP gene, although one Turkish, five German, one Korean, and 18 Japanese patients have been reported so far. The p.D157N mutation was previously reported to be the most frequent (0.389; 14/36) in Japanese patients and was also found in a Korean patient. On the other hand, this mutation has not been found in Turkish and German patients. We therefore investigated haplotypes of the patients who have the p.D157N mutation. The results showed that OCA4 is prevalent in East Asia including Japan and Korea likely as a result of a founder effect for the p.D157N mutation. Furthermore, it is suspected that the p.D157N mutation might have occurred on an ancestral chromosome after the divergence of Orientals and Caucasians.