AQP4-antibody positive NMO represents a rare chronic inflammatory disorder of the CNS as a result of an autoantibody- and complement-mediated astrocytopathy due to high expression of the antigen AQP4 at the astrocytic endfeet, which is followed by secondary demyelination and often extensive axonal and neuronal damage, which primarily affects the spinal cord, optic nerves and brain stem areas [7]. The gene discussed is AQP4; the disease is neuromyelitis optica.