Alopecia areata is one of the top two most common causes of hair loss in the world, with genetic predisposition coming in first place (called androgenetic alopecia). If you are experiencing an auto immune disorder and are affected by the results of alopecia areata, you may notice one or two bald spots that start to show up on your scalp. The spots will become larger and larger over time until your immune system gets back to normal and the hair eventually replaces itself.