Aquaporin-4 Antibodies, Neuromyelitis Optica, and Multiple Sclerosis

Two Japanese research groups independently tested an assay that uses recombinant human antigen to confirm the specificity of anti-aquaporin-4 antibodies for neuromyelitis optica.

Diagnostic criteria for neuromyelitis optica (NMO) require the presence of optic neuritis and myelitis plus at least two of the following features: (1) brain MRI not consistent with multiple sclerosis (MS); (2) “longitudinally extensive” transverse myelitis (LETM: MRI-detected cord lesion spanning ≥3 vertebral segments); and (3) seropositivity for NMO-IgG, an autoantibody that targets aquaporin-4 (Neurology 2006; 66:1485). NMO-IgG is approximately 75% sensitive for NMO (Lancet 2004; 364:2106). In Japan, Asian “opticospinal” MS (OSMS) is recognized as a distinct phenotype that comprises 30% of CNS demyelinating disease. OSMS and NMO may be the same disorder.

To assess the diagnostic utility of an assay that uses human recombinant aquaporin-4 …

Reviewing Author

Dean M. Wingerchuk, MD, MSc, FRCP(C)