INS (insulin), PTPN22, PTPN2 (protein tyrosine phosphatase non-receptor 2), IL2RA (interleukin 2 (IL2) receptor alpha), CTLA4 (cytotoxic T lymphocyte antigen-4), and IFIH1 (interferon induced with helicase C domain 1) are some non-major histocompatibility (MHC) genes associated with type 1 diabetes mellitus (T1D) [8]. The gene discussed is CTLA4; the disease is type 1 diabetes mellitus.