AQP4 and autoimmune disease: NMOSD is a pretty new umbrella term used to include aquaporin-4 IgG antibodies AQP4-IgG seropositive patients with limited forms of NMO, those with typical NMO who have cerebral, diencephalon and brainstem lesions and AQP4-IgG seropositive patients with coexisting autoimmune diseases [5].