HLA-DRB1 and type 1 diabetes mellitus: Since 85.9% of the patients had DRB1*0301, to study if the interaction of VDR with predisposing HLA alleles was mediated by VDRE present in the promoter region of the allele, we amplified the promoter region of 3 T1D subjects and 3 healthy controls homozygous for HLA-DRB1*0301.