what is alopecia disease

Alopecia areata is an autoimmune disease that causes hair loss when the immune system attacks hair follicles. Hair follicles are the structures in the skin that form hair. The extent of hair loss varies; in some cases, it is only in a few spots, while in others, the hair loss can be greater. On rare occasions, the person loses all of the hair on their head (alopecia areata totalis) or entire body (alopecia areata universalis) . The disease is unpredictable, and in some people, hair grows back but falls out again later, while in others, hair grows back and remains. The cause of alopecia areata is not entirely understood, but it is believed that a persons genetic makeup may trigger the autoimmune reaction, along with a virus or a substance the person comes into contact with. Scientists have linked a number of genes to the disease, which suggests that genetics play a role in alopecia areata. People with certain autoimmune diseases, such as psoriasis, thyroid disease, or vitiligo, are more likely to get alopecia areata, as are those with allergic conditions such as hay fever. Emotional stress or an illness can bring on alopecia areata in people who are at risk, but in most cases, there is no obvious trigger. There are three main types of alopecia areata: alopecia areata, alopecia totalis, and alopecia universalis. The main symptom of alopecia is hair loss, which can occur in small bald patches on the scalp or other parts of the body. The amount of hair loss is different in everyone, and the patches may get larger and grow together into a bald spot. Doctors don't know why it happens, but they think people who get it have something in their genes that makes it more likely.