HLA-DRB1 and myeloid sarcoma: Comparing OCB negative (n = 199) and OCB positive (n = 1453) MS patients showed that HLA-DRB1*15∶01 and HLA-DRB1*04∶04 were significantly differently distributed between OCB positive and OCB negative MS patients (p*15∶01 = 9.9×10−5, OR = 0.64, 95% CI 0.49–0.83, p*04∶04 = 0.0004, OR = 2.2, 95% CI = 1.5–3.20).