Albinism is the congenital absence of pigmentation or coloration because of the lack of or insufficient pigment production. In plants, it is caused by the partial or complete loss of chlorophyll pigments. In animals (which most of them have multiple pigments), albinism is characterized by the partial or complete lack of pigment or coloration in the eyes, skin, hair, scales, fur, feathers, or cuticle. The organism with this type of condition is referred to as albino.
In humans, albinism is characterized by the lack of pigmentation in the skin, hair, and eyes. At the biomolecular level, the cause of this disorder is the absence of or defect in tyrosinase (tyrosine 3-monooxegenase). Tyrosinase is a copper-containing enzyme that is associated with melanin production. Without a functional tyrosinase, melanin cannot be produced sufficiently and therefore, this results in congenital characteristics such as pale skin, white hair, and red eyes. Albinism may either be hypomelanism where there is only a partial lack of melanin or amenalism where melanin is completely lacking. In humans, albinism may affect skin, eyes, and hair and is termed oculocutaneous albinism or it may affect only the eyes and it is called ocular albinism. The oculocutaneous albinism is caused by mutations in genes (e.g. tyrosinase gene, tyrosinase-related protein-1 gene, P gene, etc.) controling melanin production within the melanocytes.1