As expected given the strong association of HLA-DRB1*15:01 with MS risk, we identified at least one copy of the HLA-DRB1*15:01 allele in 26.8% of controls (n = 108,917) and 49.7% of MS cases (n = 1044), yielding an odds ratio of 2.7 for MS given the presence of HLA-DRB1*15:01 (OR = 2.72, 95% CI 2.72–2.72, p < 2 × 10–16; model adjusted for age, sex, and genetical Principal Components 1–4; PCs). The gene discussed is HLA-DRB1; the disease is myeloid sarcoma.