IFNB1 and myeloid sarcoma: The aim of this work was to characterize reports of TMA and aHUS for patients with MS who received subcutaneous (sc) IFNβ‐1a, to describe a case of MS patient who developed aHUS after a long time on IFNβ‐therapy and to analyze the possibility to restart a disease‐modifying treatment (DMT), after eculizumab therapy.