Subnormal levels of serum type I interferons (IFN-α and IFN-β) plus poor in vitro responses to IFN-β by peripheral blood mononuclear cells (PBMC) implicate a fundamental defect in IFN regulation and signaling in therapy-naïve MS patients [3,5] (Fig 1). The gene discussed is IFNA1; the disease is myeloid sarcoma.