This also applies to myelin-oligodendrocyte-glycoprotein (MOG) encephalomyelitis (MOG-EM), a novel entity associated with serum autoantibodies against MOG, which phenotypically overlaps with both NMOSD and MS or may present as acute demyelinating encephalomyelitis (ADEM) and encephalitis. Here, MOG is linked to myeloid sarcoma.