Alopecia areata is a type of autoimmune disease that results in loss of hair from any place in the body (the scalp in particular) because the body's immune system detects its own root hair cells as foreign invaders (similar to a pathogen) and therefore aims to destory it  .
- ↑ Brzezińska-Wcisło, L et al. 2014. Journal. [ONLINE] Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4171667/. [Accessed 23 October 15]