Neuromyelitis optica (NMO) is a demyelinating inflammatory disorder of the central nervous system (CNS) that is clinically and pathologically defined as the co-occurrence of optic neuritis and myelitis.
1 NMO-IgG, an autoantibody that binds to human aquaporin 4 (hAQP4), is detectable in the serum of most patients with NMO.
2,3 AQP4 plays an important role in the transportation of water across the cell membrane of multiple cell types. Within the CNS, it is highly expressed in the foot processes of astrocytes.
4,5 There are 2 isoforms of hAQP4: M1 and the shorter M23 isoform, which lacks the first 22 amino acids but is otherwise identical in sequence.
6 Possibly because of the identification of the NMO-IgG antibody in patients with NMO, neurologists have focused on pharmacotherapies that predominantly target the humoral immune system.
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