Aquaporin is a family of transmembrane water channels found throughout the body of both humans and many other species, facilitating the passage of water, cations and gases 1.
At least thirteen types of aquaporin have been described, and these are variably expressed.
Aquaporin-4
Aquaporin-4 (gene: AQP4) is the most abundant water-channel in the brain, primarily located in the perivascular astrocytic endfeet, and has been implicated as critical in the glymphatic pathway.
Antibodies to AQP4 are responsible for neuromyelitis optica spectrum disorder (NMOSD).