Established T1D risk genes include the human leukocyte antigen (HLA) region, insulin (INS), protein tyrosine phosphatase non-receptor type 22 (PTPN22), interleukin-2 receptor alpha (IL2RA), and cytotoxic T-lymphocyte associated protein 4 (CTLA4), among others (12). The gene discussed is PTPN22; the disease is type 1 diabetes mellitus.