lso involved in melanin pigment formation and albinism, but the exact role of these proteins remains unknown. These genes are the P gene on chromosome 15, the Hermansky--Pudlak syndrome gene on chromosome 10, and the ocular albinism gene on the X chromosome. The gene carrying the defect that produces albinism is recessive, which means that both parents must carry this recessive gene in order to produce a child with the condition. When both parents carry the gene (and neither has albinism), there is a one in four chance with each pregnancy that their child will have albinism. The inheritance pattern of ocular albinism is alittle different. This condition is X-linked, meaning that the recessive gene for ocular albinism is located on the X chromosome. X-linked ocular albinism appears just about only in males who inherit the condition from their mothers. Albinism is a recessive inherited defect in melanin metabolism in which pigment is absent from the hair, skin, and eyes (oculocutaneous albinism) or just from the eyes (ocular Albinism). Albinos tend to be children of parents who were first cousins.For a long time, the term albinism referred only to people who had white hair, white skin, and blue eyes. Individuals who had OCA and pigmented hair and eyes were identified, particularly in the African and African-American population, and terms such as incomplete albinism, partial albinism of imperfect albinism were used for this, but these terms are inappropriate and are no longer used. In the 1960s, Dr. Carl Witkop invented the hairbulb incubation test to separate pigmenting and non-pigmenting types of OCA and stared to use the terms ty-neg or tyrosinase-negative and ty-pos or tyrosinase-positive OCA. Freshly plucked hairbulbs from a person with OCA were place in a solution of tyrosine or dopa in a test tube and watched to see if pigment formed in the cells in the hairbulb. If no pigment formed, the test was positive and the diag...
