Establishment of tyrosinase sequence database in normally pigmented Indians and Japanese for rapid determination of novel mutations.

BACKGROUND

Many mutations of the tyrosinase gene have been reported in oculocutaneous albinism type I (OCA1) patient. In the future, a greater number of novel mutations will be found as the search for pathological mutations in the tyrosinase genes of OCA patients from various ethnic origins. For rapid determination in future whether an observed mutation is a polymorphism or a novel pathological one, sequence databases of the gene of various ethnic people are needed.

OBJECTIVE

We established a sequence database of the tyrosinase gene of Japanese as well as Indian people.

METHOD: We collected DNA from 109 Japanese and 103 Indians with normal pigmentation and analyzed their tyrosinase gene using a direct sequencing method.

RESULT: The database shows an apparent difference between the two ethnic groups in polymorphisms of the tyrosinase gene namely, Q402 allele, Y192 allele and IV2+24 insT were found in the Indian population, but not in the Japanese. On the other hand, some Japanese had IV2-21 insT but none of the Indians did. The database supports the notion that the tyrosinase gene evolved and extended separately in the two ethnic groups. And the developing database confirmed that the reported mutations causing Indian and Japanese OCA were not among the polymorphisms in the database, which conversely gives genetical proof of the "genuine" pathological mutations.

CONCLUSION

Eventually, the sequence database we established will contribute to demonstrating novel mutations of albinism in Indians and Japanese.