A 41-year-old woman with acute weakness and encephalopathy associated with MOG antibodies

Antibodies to native glycosylated myelin oligodendrocyte glycoprotein (MOG), measured by cellbased assays, have been reported in adults with acute disseminated encephalomyelitis (ADEM) and in children with demyelinating diseases, including multiple sclerosis (MS) and ADEM. More recently, antibodies to both truncated and full-length MOG have been identified in a few adults with aquaporin-4 (AQP4) antibody–negative neuromyelitis optica spectrum disorder (NMOSD). We report a patient with a rapidly worsening longitudinally extensive transverse myelitis (LETM) whose serum antibodies were subsequently found to bind the full-length version of MOG. Aggressive and early immunomodulation correlated closely with reduction in MOG titer and clinical improvement.