HLA-DRB1 and type 1 diabetes mellitus: The acetylation level of lysine 9 of H3 histone protein (H3K9Ac) in the type 1 diabetes susceptible genes, HLA class II histocompatibility antigen, DRB1 β chain (HLA-DRB1) and HLA-DQB1, was found to be higher in T1D patients as compared with the normal individuals [28].