AQP4 and neuromyelitis optica: Interestingly the commensal bacterium, Clostridium perfringens showed increased relative abundance in the patients of neuromyelitis optica (110) than the healthy controls and the adenosine triphosphate-binding cassette (ABC) transporter permease sequences of C. perfringens shared homology with T cell epitope with the Aquaporin 4 with the possibility of mimicry from the gut (108).