SNPs for autoimmune diseases include major histocompatibility complex, class II, DR Beta 1 gene HLA‐DRB166 (mainly associated with rheumatoid arthritis), tumor necrosis factor receptor type 1 gene (TNFRSF1A)95 (mainly associated with multiple sclerosis and ankylosing spondylitis), and protein tyrosine phosphatase nonreceptor type 22 gene (PTPN22)29 (mainly associated with increased risk of type 1 diabetes, systemic lupus erythematosus, vitiligo,119 autoimmune thyroid disorder,120 and ulcerative colitis121 but is protective against Crohn's disease). The gene discussed is PTPN22; the disease is Crohn disease.