The possibility that there were neuroepithelium alterations in some cases of NMO, which allowed the anomalous presence of AQP4 in the CSF thereby causing an autoimmune reaction and the possible generation of AQP4-Ab, could explain the physiopathology of several kinds of NMOSD such as seronegative cases for AQP4-Ab [25]. Here, AQP4 is linked to neuromyelitis optica.