What is AQUAPORIN-4 (NMO) Antibody?

Aquaporin 4 (AQP4) is a water channel protein found on cells known as astrocytes that surround the blood-brain barrier, (a layer of cells responsible for preventing dangerous substances in the blood from crossing into the brain). It is presumed that the blood-brain barrier allows the AQP4 antibodies to enter the central nervous system. This causes inflammation and demyelination and symptoms of a relapse.

Approximately 80% of people diagnosed with NMOSD have Aquaporin 4 antibodies in their blood.

When to test for AQP4 Antibodies

• If a patient has recurrent, bilateral or severe optic neuritis
• If a patient has longitudinal, or recurrent transverse myelitis
• If lumbar MRI spine shows a lesion greater than 3 vertebrae
• If a patient has poor recovery from MS relapses

If the test is positive, please refer the patient to one of the centers.

However 20% of people with NMOSD do not have Aquaporin 4 antibodies, If you have any concerns regarding diagnosis or management, please refer to the NMO service.

Useful For

• Diagnosis of a neuromyelitis Optica spectrum disorder (NMOSD)
• Diagnosis of autoimmune AQP4 channelopathy
• Diagnosis of neuromyelitis Optica (NMO)
• Distinguishing NMOSD from multiple sclerosis early in the course of the disease

Testing Algorithm

When the results of this assay require further evaluation, NMOTS / Neuromyelitis Optica (NMO)/Aquaporin-4-IgG Fluorescence-Activated Cell Sorting (FACS) Titer Assay, Serum will be performed at an additional charge.

Method Name

Flow Cytometry

Aliases

• AQP
• AQP4
• Aquaporin
• Devic's Antibody
• NMO (Neruomyelitis Optica)
• NMO-IgG
• Optic Neuritis Antibody
• Transverse Myelitis Antibody
• Vision Loss Antibody