A previous study reported that Scandinavian and German MS patients with anti-JCV antibodies had a significantly lower frequency of the human leukocyte antigen (HLA)-DRB1*15 haplotype than those without anti-JCV antibodies, suggesting the DRB1*15 haplotype is negatively associated with anti-JCV antibody positivity [13]. The gene discussed is HLA-DRB1; the disease is myeloid sarcoma.