Alopecia areata is an autoimmune disease that results in hair loss in small coin shaped or larger round patches. These localized areas of hair loss will most commonly spontaneously regrow hair, however sometimes they may last for many years or spread to involve more extensive body areas.
Alopecia areata is somewhat common; almost 2% of the U.S. population will experience it during their lifetime. We do not understand what triggers the body's immune system to attack and destroy its own hair follicles.
Alopecia areata does not favor gender or ethnicity. Most commonly children and young adults are affected, but it can occur in people of any age. There is probably a hereditary component to alopecia areata, one in five people with alopecia areata also have an affected family member. Dermatologists believe these individuals have a genetic predisposition to the disease.