Another pathological condition that involves AQP4 is neuromyelitis optica spectrum disorder (NMOSD), in which patients produce anti-AQP4 antibodies that target astrocytes, thus damaging the BBB, and allowing for further damage to arise due to the chemoattraction of polymorphonuclear leukocytes; notably, however, BBB repair precedes repopulation by astrocytes [225]. This evidence concerns the gene AQP4 and neuromyelitis optica.