In contrast, samples of patients with lower AQP4-IgG antibody titers and all investigated serum samples of AQP4-IgG negative CNS demyelinating diseases and controls were not able to activate the complement cascade on the surface of AQP4-expressing HEK-293A cells (Table 3 and additional file 3). The gene discussed is AQP4; the disease is demyelinating disease of central nervous system.