The National Alopecia Areata Foundation says only about 20 percent of alopecia areata cases are hereditary, unlike androgenic alopecia (permanent patterned balding), where heredity plays a more prominent role.
No diagnostic test has been developed for alopecia areata, but an experienced dermatologist most often can identify it. Doctors sometimes need to take a small skin biopsy for a definitive diagnosis. The disorder causes patchy hair loss, often appearing as smooth patches on small areas at various locations on the scalp (occasionally, on other body parts as well). These patches can appear suddenly, as quickly as 24 hours, and some people report feeling tingling or pain at the site.
Various types of alopecia areata include:
- Alopecia totalis - An advanced alopecia areata resulting in total hair loss on the scalp
- Alopecia universalis - Another advanced alopecia areata resulting in hair loss over the entire body
- Traction alopecia - Where hair loss is caused by physical stress and tension on the hair.