HLA-DRB1 and myeloid sarcoma: Furthermore, because HLA-DRB1*15.01 is the main genetic risk factor in MS development, and its expression is regulated by VDR, all of the subjects were characterized for HLA-DRB1*15.01 and clustered on the basis of positivity, finding that HLA-DRB1*15.01 did not correlate with the outcome of MDR.