What is vitiligo?

Vitiligo consists of white patches of skin that are caused by the loss of melanin, the pigment that gives skin its color. Melanin is produced by special cells called melanocytes, which are destroyed in people who have vitiligo. No one knows exactly why these cells are destroyed, but one theory is that vitiligo is an autoimmune disorder, in which the body's immune system mistakenly targets the body's own cells rather than protect them from outside invaders.

People experience different degrees of vitiligo. In some people, it may be hardly noticeable, while in others it is obvious. Dark-skinned people may notice more contrast between the vitiligo patches and their normal skin, while light-skinned people may not notice much of a difference, or may notice it only in the summer when they tan.

People with vitiligo have an increased risk of developing autoimmune diseases, such as hypothyroidism (an underactive thyroid), hyperthyroidism (an overactive thyroid), Addison's disease (a disease that causes a decrease in the function of the adrenal gland) and pernicious anemia (vitamin B12 deficiency).

This disease affects an estimated 1% of the world's population. It affects individuals of all ethnic origins and both sexes, but is much more easily noticed on darker skin as areas that fail to tan. It is hereditary in one third of those affected. Vitiligo often starts on the hands, feet or face, and frequently pigment loss is progressive. Half the patients first notice vitiligo before 20 years of age. It often appears in an area of minor injury or sunburn.

It is believed that vitiligo is an autoimmune disorder (autoimmune means the bodies own immune system turns on itself). Certain white blood cells direct the destruction of melanocytes. People with vitiligo are also somewhat more prone to other autoimmune diseases, such as alopecia areata, autoimmune thyroid disorders, Addison's disease, pernicious anemia, and diabetes mellitus.

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