"Alopecia areata is an autoimmune disorder that causes your hair to come out, often in clumps the size and shape of a quarter. The amount of hair loss is different in everyone. Some people lose it only in a few spots. Others lose a lot. Sometimes, hair grows back but falls out again later. In others, hair grows back for good."
Alopecia Definition Website Link HERE
This cause is very near and dear to my heart, because I have been effected by this autoimmune disorder. When I was 16 was when I first lost all of my hair. It grew back, but when I was 20 it all fell out again.
Link to Alopecia Advocacy website HERE