A 52-year-old man presented with TMA caused by ADAMTS13 deficiency after treatment with IFN-β.55 Three women with RRMS treated with high doses of INFβ-1a were diagnosed with thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) when they presented with blurred vision, cephalalgia, confusion, arterial hypertension, seizures, and focal deficits associated with hemolytic anemia and thrombocytopenia.56 A 36-year-old patient with RRMS who had been treated with subcutaneous (SC) INF-β1a was hospitalized due to progressive dyspnea, systolic dysfunction and pulmonary hypertension. The gene discussed is ADAMTS13; the disease is thrombotic thrombocytopenic purpura.