Individuals with anti-aquaporin-4 (AQP4) antibodies and anti-myelin oligodendrocyte glycoprotein (MOG) antibodies were previously grouped under the umbrella term neuromyelitis optica spectrum disorder (NMOSD), as they shared two cardinal clinical manifestations, optic neuritis and longitudinally extensive transverse myelitis. This evidence concerns the gene AQP4 and optic neuritis.