She was then re-admitted to the hospital with urosepsis, and new demyelinating lesions were found (Figures 1G–I); persistently elevated ferritin, C-reactive protein (CRP), and interleukin-2 (IL-2) receptor levels raised concerns of hemophagocytic lymphohistiocytosis (HLH) with CNS involvement, as well as possible macrophage activation syndrome (MAS), consequently, treatment with anakinra and cyclosporine was initiated. This evidence concerns the gene IL2 and macrophage activation syndrome.