Central nervous system (CNS) autoimmune demyelinating disorders present with a broad clinical disease spectrum, including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), anti-myelin oligodendrocyte glycoprotein-associated disease (MOGAD), acute disseminated encephalomyelitis (ADEM), and glial fibrillary acidic protein (GFAP)-associated meningoencephalomyelitis. The gene discussed is MOG; the disease is neuromyelitis optica.