PTPN22 and alopecia areata: SNPs in PTPN22 gene are linked to an increased risk of developing autoimmune diseases such as Alopecia Areata, RA, Graves’ Disease, Primary Sjogren Syndrome, Generalized Vitiligo, Myasthenia Gravis, Addison Disease, Systemic Sclerosis, and SLE by enhancing T-cell proliferation and activation of T-cells (20).