Alopecia areata is an autoimmune disease that causes the body's immune system to attack the hair follicles, resulting in patchy hair loss, which can occur on the scalp or anywhere else on the body. It can affect people of all ages, genders, and skin tones, and the onset can be at any age, although it often begins in children and young adults. The disease can manifest in various forms, such as patchy hair loss on the scalp (alopecia areata), a band or strip of hair loss on the scalp (alopecia ophiasis), complete loss of hair on the scalp (alopecia totalis), or complete loss of hair on the scalp and body (alopecia universalis)
Alopecia areata is characterized by sudden loss of round or oval patches of hair, and in some cases, it can progress to complete loss of body hair. The condition is not limited to the scalp and can also affect areas such as the beard, eyebrows, or eyelashes. While the exact cause of alopecia areata is not fully understood, it is believed to be related to genetics, as scientists have linked a number of genes to the disease, indicating a role for genetics in its development