ddiseasesanddisorders

Vitiligo to predict how much pig- s ment an individual will The pigment found in the skin, retina, and hair of human beings lose. Its incidence is is called melanin and is produced in melanocyte cells. If these cells higher in people with thy- die or cannot form melanin, the result is a skin condition called roid conditions and some vitiligo, in which the skin becomes lighter or completely white in other metabolic diseases, patches, usually on the face, lips, hands, arms, legs, and genital but most patients are in areas. Because of the social effects of the change in appearance, good health and suffer no it is considered by many to be a skin disorder that has more soci- symptoms other than etal than medical significance. areas of pigment loss. Medical researchers are not sure what causes vitiligo, but some The first cases of 1803 engraving of man with vitiligo. believe it originates from both genetic and environmental factors. vitiligo were recorded in Vitiligo sometimes runs in families, and one study conducted by the religious texts such as the Bible and the Koran. University of Florida College of Medicine (Genes Immun. 2003, There are several treatment options for the disease. The easi- 4, 492–499) found that 20% of the relatives of vitiligo patients also est is disguising the patches with makeup, self-tanning com- have the disease—suggesting that some people are born with pounds, or skin dyes, which is considered a safe, albeit temporary, genes that make them more likely to way to make the patches less noticeable. In small areas of vitiligo, develop vitiligo. Environmental factors O repigmentation therapy is an alternative. This consists of apply- such as traumatic skin injury, sun- ing topical corticosteroid creams, which can be effective in return- burn, or stress also appear to influence ing pigment to small areas; and they can be used with other the likelihood that an individual with treatments. Although effective, these agents can thin the skin or N those “susceptibility genes” will O H even cause stretch marks in certain areas. develop vitiligo. Some researchers Treatment with psoralen and ultraviolet A (PUVA) is another Melanin. believe the body develops an allergy form of repigmentation therapy. The skin is treated with a special to its own pigment cells, while others think that the cells may destroy type of ultraviolet light, and the psoralen is applied to the vitiligo themselves during the process of pigment production. In some areas. Psoralen is also given in pill form. Treatment with PUVA patients, disease progression appears to involve inappropriate acti- has a 50–70% chance of returning color on the face, trunk, and upper vation of an immune response against melanocytes; therefore, arms and legs, and a year of twice-weekly treatments is required. vitiligo is considered to be an autoimmune disease. Research on the Side effects include sunburn-type reactions. When used long- cause is ongoing. term, freckling may result, and the Vitiligo is also known as leuco- risk of skin cancer increases. derma, which means white (leuco) Another form of treatment, per- skin (derma). It is also medically Conditions similar to vitiligo haps the most drastic, is depig- known as achromia, which means mentation therapy. This consists l Albinism—the result of altered genes that cause a defect in loss of color. The ailment affects of removing the remaining pig- melanin production, which results in the partial or full absence of 1–2% of the world’s population, ment from normal skin and mak- pigment from the skin, hair, and eyes. roughly 40–50 million people, but ing the whole body an even white l Atopic dermatitis—commonly referred to as eczema, a the degree of pigment loss varies color. The procedure is done with chronic skin disorder characterized by scaly and itchy rashes. between individuals and even within a chemical called monobenzyl l Discoid lupus erythematosus—a chronic, inflammatory, each vitiligo patch. There may be ether of hydroquinone. The ther- autoimmune disorder that may affect many organ systems, includ- different shades of pigment in a apy takes about a year to complete ing the skin, joints, and internal organs. patch, or a border of darker skin and is permanent. The National l Lichen planus—a disorder of the skin and mucous mem- may circle an area of light skin (see Vitiligo Foundation, among others, branes resulting in inflammation, itching, and distinctive skin illustration). People with fair com- is diligently searching for an exact lesions. plexions usually notice the contrast cause and, eventually, a cure. l Seborrheic dermatitis—loose, dry or greasy, white to yel- between areas of vitiligo and sun- lowish scales with or without associated reddened skin. Cradle tanned skin, but for the most part, For more information cap is the term used when seborrheic dermatitis affects the scalp vitiligo is more obvious in people American Vitiligo Research Founda- of infants. tion; www.avrf.org. with darker skin. Individuals with l Tinea versicolor—a chronic fungal infection of the skin. Medline Plus; www.nlm.nih.gov/med severe cases can lose pigment all lineplus/vitiligo.html.

over the body, and there is no way —FELICIA M. WILLIS o PHOTO: NATIONAL LIBRARY OF MEDICINE

64 MODERN DRUG DISCOVERY FEBRUARY 2004  2004 AMERICAN CHEMICAL SOCIETY