HLA-DQA1 and type 1 diabetes mellitus: Twin and family studies demonstrate that genetic factors contribute to ~50% of the risk of type 1 diabetes [10, 11], with variation in HLA class I (HLA-A, HLA-B, HLA-C) and HLA class II (HLA-DRB1, HLA-DQA1, HLA-DQB1) accounting for 30%- 50% of genetic risk [12].