AQP4 and neuromyelitis optica: Even more recently, anti-MOG antibodies have also been identified in a subgroup of AQP4-seronegative pediatric and adult patients with neuromyelitis optica spectrum disorder (NMOSD) presenting with a distinct and more benign clinical phenotype with strong correlation to uni-/bilateral recurrent optic neuritis [68,71,72,74,75,76,77,78].