Neuromyelitis optica (NMO) is a central nervous system (CNS) autoimmune disorder that preferentially affects the optic nerve and spinal cord, and the discovery of the disease specific antibody, NMO-IgG (anti-aquaporin-4-antibody, AQP4-ab) has widened the spectrum of NMO-related disorders (NMO spectrum disorder, NMOSD) [11], [12]. Here, AQP4 is linked to neuromyelitis optica.