Overview of alopecia areata.

Alopecia areata is a complex genetic, immune-mediated disease that targets anagen hair follicles. The disease affects children and adults and is characterized by round or oval patches of hair loss, loss of all scalp hair (alopecia totalis), body hair (alopecia universalis), or ophiasis pattern hair loss. Patients may also present with patchy loss in multiple hair-bearing areas. Commonly associated diseases include asthma, allergic rhinitis, atopic dermatitis, thyroid disease, and automimmune diseases, such as thyroiditis and vitiligo. Nail abnormalities may precede, follow, or occur concurrently with hair loss activity. Alopecia areata has no known age, race, or ethnic preponderance and in contrast to other autoimmune diseases such as thyroiditis or lupus, the hair follicle does not usually sustain permanent injury and maintains its potential to regrow hair. It is estimated that alopecia areata affects between six and seven million individuals in the United States. Genes, the immune and nervous systems have all been implicated in the pathogenesis of alopecia areata. Although many treatments are available, there is still no cure. Bolstered by new scientific and translational opportunities from recently published genome-wide association studies, an ambitious treatment development program has recently been initiated by the National Alopecia Areata Foundation.