Neurological syndromes include anti–N-methyl-D-aspartate receptor (NMDAR) encephalitis, limbic encephalitis, encephalomyelitis, neuromyelitis optica spectrum disorder [NMOSD; associated with aquaporin-4 (AQP4) antibodies], myelin oligodendrocyte glycoprotein (MOG)-associated disease, glial fibrillary acidic protein (GFAP) astrocytopathy, progressive cerebellar degeneration, and opsoclonus–myoclonus syndrome (OMS) (17). The gene discussed is AQP4; the disease is opsoclonus-myoclonus syndrome.