Area postrema syndrome (APS), which refers to episodes of intractable nausea, vomiting or hiccups mimicking gastrointestinal disorders, is one of the six core clinical characteristics of aquaporin-4 (AQP4)-IgG seropositive neuromyelitis optica spectrum disorder (NMOSD). The gene discussed is AQP4; the disease is autoimmune polyendocrinopathy.