These studies have found convincing evidence of associations of several loci with T1D: HLA class II genes on chromosome 6p21, INS on 11p15, CTLA4 on 2q33, PTPN22 on 1p13, the IL2Rα region on 10p15 and the IFIH1 region on 2q24. Here, CTLA4 is linked to type 1 diabetes mellitus.