A Case of Oculocutaneous Albinism Induced by Tyrosinase Mutation

Kim, Won Jeong; Kim, Su Han; Jung, Do Sang; Ko, Hyun Chang; Kim, Moon Bum; Kwon, Kyung Sool

Abstract

Oculocutaneous albinism (OCA) is a group of inherited disorders of the melanin synthesizing system, and these are characterized by hypopigmentation of the hair, skin and eyes, with a normal number of melanocytes. The defect of melanin biosynthesis is caused by genetic mutation of such enzymes as tyrosinase (TYR), and tyrosinase-related protein (TYRP), which affect tyrosine convert to melanin pigment. There are at least four types of OCA from OCA1 to OCA4. The different types of OCA are caused by mutations in different genes. The most severe form, OCA1A, is distinguishable from other forms owing to a complete lack of melanin pigment throughout the patient's whole life. But among other types, except OCA1A, it is hard to identify the correct type according to only the clinical findings because their clinical phenotypes usually overlap. Therefore, molecular study is a useful tool for the typing and diagnosis of OCA. We experienced a case of a 10-month-old male toddler who has pale skin, straw-colored hair, nystagmus and visible choroidal vessels. Under the clinical impression of OCA, the correct subtyping was made on the basis of genetic analysis of the chromosomes and we found a new TYR gene frame-shift mutation.