The strongest genetic risk factors for T1D are located in the major histocompatibility complex (MHC, also called the human leukocyte antigen: HLA) class II on chromosome 6, with the predisposing HLA class II haplotypes found in around 90% of patients with T1D [45]; the specific combination of HLA II alleles HLA-DRB1*03 (DR3) or HLA-DRB1*04 (DR4) with DQB1*03:02 (DQ8) confer the highest risk for T1D (for details on HLA susceptibility please see an excellent previous review [46]). This evidence concerns the gene HLA-DRB1 and type 1 diabetes mellitus.