In the context of genetic predispositions of MS, sequence analysis localizes a single MHC vitamin D response element (VDRE) to the promoter region of Human Leukocyte Antigen DRB1 (HLA-DRB1) which is conserved in MS HLA-DRB1 homozygotes; thus, expression of MS-associated MHC class II allele HLA-DRB1*1501 is regulated by vitamin D. Polymorphisms of the VDR may influence vitamin D function and metabolism [82]. The gene discussed is HLA-DRB1; the disease is myeloid sarcoma.