HLA-DRB1 and type 1 diabetes mellitus: In 2008, Erlich and colleagues identified a cluster of 3 genes with a very high risk of T1D, known as a “superlocus” in HLA-DRB1–HLA-DQA1–HLA-DQB1 region responsible for encoding the HLA-DR-DQ proteins for HLA class II expression (Erlich et al, 2008).