The diagnostic criteria characterize NMO by optic neuritis, myelitis, and at least 2 of the following 3 criteria must be present: longitudinally extensive cord lesion, magnetic resonance imaging nondiagnostic for MS, and NMO-IgG seropositivity.[3–6] The serum autoantibody NMO-IgG, which targets aquaporin-4, is a good candidate because it is >90% specific for NMO in patients presenting with an optic-spinal syndrome and is not detected in patients with classic MS. This evidence concerns the gene AQP4 and neuromyelitis optica.