AQP4 and autoimmune polyendocrinopathy: The term "NMO spectrum disorder (NMOSD)" has been advocated as a broader concept for AQP4 antibody-seropositive diseases, and consensus diagnostic criteria of NMOSD with anti-AQP4 antibody need at least one core clinical characteristic, including optic neuritis, acute myelitis, area postrema syndrome (APS), acute brainstem syndrome, symptomatic narcolepsy, acute diencephalic clinical syndrome, and symptomatic cerebral syndrome [2].