AQP4 and neuromyelitis optica: Thus, the purpose of this study was (i) to evaluate to what extent NMO sera (AQP4‐IgG+) are able to recognize AQP4‐expressing skeletal muscle fibres versus AQP4 expressed in brain and (ii) to provide information on AQP4 isoform expression and OAP pool composition, tissue‐specific suprastructure organization and their effect on NMO epitope binding.