Oculocutaneous albinism type 3: A Japanese girl with novel mutations in TYRP1 gene

Abstract

Oculocutaneous albinism (OCA) type 3 caused by mutations of the TYRP1 gene is an autosomal recessive disorder of pigmentation characterized by reduced biosynthesis of melanin pigment in the skin, hair, and eye. The clinical phenotype has been reported as mild in Caucasian OCA3 patients. We had the opportunity to examine a Japanese girl with OCA3 and investigated activity of TYRP1 protein derived from the mutant allele detected in the patient. Mutation search for OCA responsible genes was done. A mutant allele with a missense mutation was analyzed using melanocyte cultures (b cells) established from a mouse model of OCA3. Compound heterozygous mutations, p.C30R and p.367fsX384, were detected in the Japanese girl. Then we revealed that the missense mutation, p.C30R, was functionally incapable of melanin synthesis with in vitro experiments. This is the first report of the occurrence of OCA3 in Japanese population.