However, in the context of the vitamin D, Treg cell, and DRB1*1501 epigenetic hypothesis of MS risk (Figure 1D), it seems plausible that reduced 1,25(OH)2D3-VDR signaling and MET cycle flux could decrease DNA methylation within the MHC class II DRB1*1501 MS risk allele, causing inappropriate expression and dysregulation within the CD4+ T cell compartment. The gene discussed is HLA-DRB1; the disease is myeloid sarcoma.