CTLA4 and type 1 diabetes mellitus: In addition, several non-MHC genes including INS (insulin), PTPN22 (lymphoid tyrosine phosphatase protein), CTLA4 (cytotoxic T-lymphocyte-associated antigen 4), IL2RA (interleukin 2 receptor α), STAT3, STAT4, IL10, IL19, IL20, IL27, and CD69 have been implicated in the development of T1D [2].