Albinism

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Overview, Causes, & Risk Factors

An amino acid called tyrosine is normally converted by the body to the pigment melanin. Albinism results when the body is unable to produce or distribute melanin because of one of several possible defects. In particular, defects in the metabolism of tyrosine leading to failure to convert it into melanin, can cause albinism.

Albinism appears in different forms and may be inherited by one of several modes: autosomal recessive, autosomal dominant, or X-linked inheritance. Complete albinism involves a total absence of pigment from the hair, eyes, and skin (this is also called tyrosinase-negative oculocutaneous albinism). It is the most severe form of the condition. Affected people may appear to have hair, skin, and iris color that are white as well as vision defects. They also have photophobia (sunlight is painful to their eyes), they sunburn easily, and do not tan.

Albinism of just the eyes also occurs. This is called ocular albinism. In this form of albinism, skin color is usually normal and eye color may be in the normal range. However, examination of the eye will show that there is no pigment in the retina.

Other complex diseases may be associated with a partial or varying degrees of localized albinism (loss of pigment in only a specific area). These include:

• Waardenberg syndrome (often a white forelock - a lock of hair that grows on the forehead, or absence of pigment in one or both irises)
• Chediak-Higashi syndrome (diffuse but not complete depigmentation of skin)
• Tuberous sclerosis (white leaf macule) -- small localized areas of depigmentation)
• Hermansky-Pudlak syndrome (generalized albinism) -- also associated with a bleeding disorder