Albinism

Alternative names:

piebaldism

Definition:

An inherited defect of melanin production that results in partial or full absence of pigment from the skin, hair, and eyes.

Causes, incidence, and 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 melanin because of one of several possible defects in the metabolism of tyrosine.

Albinism appears in different forms and may be inherited by one of several modes: autosomal recessive, autosomal dominant, or X-linked. 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 have white hair, colorless skin, red irises, and 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 and may be associated with several inheritable disorders. Piebaldism, or partial albinism, is a condition associated with a patchy absence of pigment. This may occur as a white forelock of hair, or as depigmented spots on the forehead, elbows, knees, or other body areas.

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