AQP4 and neuromyelitis optica: Myelin oligodendrocyte glycoprotein antibody-associated autoimmune disease (MOGAD) is a rare inflammatory demyelinating disease of the central nervous system (CNS), which causes a broad spectrum of atypical, partly multiple sclerosis (MS)-mimicking demyelinating CNS syndromes including (recurrent) optic neuritis (ON), myelitis, aquaporin-4 (AQP4)-seronegative neuromyelitis optica (NMO)-like disease, (brainstem) encephalitis and others (1).