For example, a misssense SNP (R620W, rs2476601) in protein tyrosine phosphatase non-receptor type 22 (PTPN22) has been shown to be associated with several autoimmune diseases including T1D, rheumatoid arthritis and Crohn's disease (CD) but with opposite directions of association [39]. Here, PTPN22 is linked to type 1 diabetes mellitus.