OCA typing and causative genes: All OCA types are caused by impaired melanin synthesis and are autosomal recessive disorders. According to the different genes involved, OCA is generally divided into four subtypes, namely oculocutaneous albinism types I, II, III, and IV (referred to as OCAl-4), which are caused by mutations in the tyrosinase (TYR) gene, P gene (proteingene), tyrosinase-associated protease 1 (TYRP a 1) gene, and The mutation of MATP (membrane-associated transporter protein) gene caused. 1, OCAl: OCAl is caused by mutations in the TYR gene. In humans, the IYR gene is located at 1lql4.3, with a total length of about 65 kb, containing 5 exons and 4 introns.TYR is derived from embryonic neural crag cells and is a key enzyme for melanin synthesis. The complete loss of tyrosinase activity in OCAl can be divided into two types: OCAlA and OCAlB, which are indistinguishable at birth. The skin, hair and eye pigment can increase with age and can be tanned. 2, OCA2: OCA2 has a high incidence in African and African-American people and is the most common type. OCA2 has a milder phenotype than OCAl, but the skin phenotype is diverse, with mild to moderate hair, skin and iris pigmentation. Skin pigmentation tends to aggregate into freckles or moles rather than being uniformly distributed, and skin color does not deepen under sunlight. The typical OCA2 phenotype includes yellow hair, white skin, blue/light brown/light brown iris, and nystagmus, strabismus, and decreased visual sensitivity due to abnormalities in the optic nerve conduction pathway. Individuals with OCA2 are born with a small amount of hyperpigmentation in the hair and iris, and as they age, the hair color increases and gradually becomes yellow to brownish-yellow. OCA2 patients may have slightly milder ocular symptoms than OCAlA, but the skin, hair color and ocular clinical manifestations are not easily distinguished from OCAlB. 3, OCA3: is caused by mutations in the gene encoding TYRP-1 located at 9p23. The human TYRP-1 gene is about 15 to 18 kb long, including 8 exons and 7 introns. oca3 was first discovered in blacks, and the pigment synthesized in patients with oca3 is not black but brown, and its clinical manifestations are characterized by light brown hair, light brown skin, blue/brown iris, nystagmus and decreased vision. OCA4: OCA4 is caused by the MATP gene located at 5p13.3. The MATP gene is about 40 kb in length, containing 7 exons and 6 introns, and most patients with OCA4 have reduced visual acuity and nystagmus. OCAl and OCA2 can be distinguished from each other by their phenotypes. In addition to the above four types, recent studies have found that there may be other types of OCA.