ALBINISM

The term albinism refers to a group of congenital genetic conditions resulting from an inability of the pigment cell (melanocyte) to synthesize normal amounts of melanin pigment. It is caused by mutations in at least 18 genes. Reduced melanin synthesis in the melanocytes of the skin, hair, and eyes produces oculocutaneous albinism, whereas a reduction primarily involving the iris and retinal pigment epithelium produces ocular albinism. Hermansky–Pudlak syndrome includes the triad of oculocutaneous albinism, a mild bleeding diathesis, and a ceroid storage disease affecting primarily the lungs and the gut. Oculocutaneous albinism is the most common autosmal recessively inherited disorder of generalized hypopigmentation, with an estimated frequency of 1 in 20,000 in most populations. It has been described in all ethnic groups and in all animal species, making it one of the most widely distributed genetic disorders in the animal kingdom. Ocular albinism, an X-linked condition, is less common with an estimated frequency of 1 in 50,000 to 1 in 60,000. Hermansky–Pudlak syndrome is a rare autosomal recessively inherited condition in most populations. In the Puerto Rican population, two forms are found, with type 1 having an estimated frequency of approximately 1 in 1800.