aquaporin-4
Water channel protein targeted by antibodies in neuromyelitis optica spectrum disorders.
Full Definition
Aquaporin-4 (AQP4) is the predominant water channel protein in the central nervous system, highly expressed on astrocyte endfeet at the blood-brain barrier and around blood vessels. In neuroimmunology, AQP4 is the target antigen for pathogenic antibodies in neuromyelitis optica spectrum disorder (NMOSD), an autoimmune inflammatory demyelinating disease of the CNS. Anti-AQP4 antibodies cause complement-mediated astrocyte damage, leading to secondary demyelination and characteristic clinical features including optic neuritis and longitudinally extensive transverse myelitis. Testing for AQP4 antibodies is essential for diagnosing NMOSD and distinguishing it from multiple sclerosis, as the treatments differ significantly.
Usage
Usage note: Often abbreviated as AQP4, particularly when referring to antibodies (anti-AQP4).
In Context
- "The patient tested positive for aquaporin-4 antibodies, confirming the diagnosis of neuromyelitis optica." — Laboratory report
- "Anti-aquaporin-4 antibody-positive patients require different therapeutic approaches than those with multiple sclerosis." — Treatment guideline