Additionally, non-HLA genes contributing to T1D risk are predominantly involved in immune tolerance, immune function and β- cell function; these genes include insulin, protein tyrosine phosphatase nonreceptor type 22 (PTPN22), cytotoxic T-lymphocyte associated antigen 4 (CTLA4), and interleukin 2 receptor alpha (IL2RA), among others (2, 7). Here, CTLA4 is linked to type 1 diabetes mellitus.