CTLA4 and type 1 diabetes mellitus: 15% of the genetic predisposition for developing type 1 diabetes is attributed to the insulin promotor (insulin-linked variable number of tandem repeats INS-VNTR, chromosome 1p5,511p15), the cytotoxic T-Lymphocyte Antigen-4 receptor (CTLA-4, chromosome 2q33), protein tyrosine phosphatase N22 (PTPN2), and the immune signaling regulator (PTPN22, chromosome 1p13) as well as other genes [28,29].