albinism

Albinism is an inherited condition in which the body makes little or no melanin, the pigment that colors skin, hair and eyes. Think of melanin as the body's ink: without enough of it, hair and skin appear very pale and the eyes lack their usual pigment. Because that same pigment is needed for the eye to develop and work normally, albinism also affects vision, often causing reduced sharpness and sensitivity to bright light.

Most forms of albinism are autosomal recessive: a child must inherit a faulty copy of the relevant gene from each parent. Several different genes can be involved, many of them in the pathway that builds melanin, such as the gene for the enzyme tyrosinase that performs a key early step. A fault anywhere along that production line can reduce or block pigment, which is why albinism can result from mutations in any of several genes.

Albinism is a clear example of how one biochemical pathway can underlie a visible trait, and of allelic and genetic variety, different mutations and different genes producing related forms. The main practical concern is eye and skin care, including protection from sun. This entry uses encyclopedic terms and is educational reference, not a value judgment or medical advice.