The expression of the MS risk gene HLA-DRB1*1501 is regulated by a vitamin D responsive promoter (124), and the level of serum 1,25(OH)2D3 in MS patients is inversely correlated with disease progression (125, 126), new CNS lesion formation (127), and risk of relapse (128, 129). Here, HLA-DRB1 is linked to myeloid sarcoma.