We stratified individual HLA-DRB1 genotypes conferring different risks for T1D confirming the main contribution of the HLA-DRB1 locus to T1D risk and demonstrated that the INS and PTPN22 genes provided only a marginal additional risk for T1D in subjects carrying the high, moderate and low risk HLA-DRB1 genotypes. The gene discussed is HLA-DRB1; the disease is type 1 diabetes mellitus.