Studies in observational cohorts of patients with MS had previously employed propensity score-weighted analyses to evaluate disease outcomes, [5], [15]–[17] propensity score-based stratification to assess long-term benefits of early versus delayed immunomodulatory treatment [7], [18] and propensity score matching to evaluate sex difference in response to IFNβ. The gene discussed is IFNB1; the disease is myeloid sarcoma.