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Neuromyelitis Optica (NMO) Spectrum Disorders

Aquaporin-4-IgG Cell-Binding Assay Offers Increased Sensitivity and Specificity



December 2013

New Method for Testing at Mayo Clinic

Because early diagnosis and differentiation of NMO spectrum disorders are critically important to assure the most appropriate early treatment, assays that are both highly sensitive and specific are essential. Mayo Clinic studies, involving thousands of patients, have found the cell-based AQP4 antibody assay to be more sensitive and specific than ELISA methods. The improved sensitivity and specificity of the AQP4 test offered by Mayo Medical Laboratories will assist clinicians in distinguishing early stage NMO spectrum disorders from multiple sclerosis.


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Featured Test:

  • Neuromyelitis Optica (NMO)/Aquaporin-4-IgG Cell-Binding Assay: Serum | CSF
 
Cell-Binding Assay
ELISA
Indirect immunofluorescence
Sensitivity1
70-75%
60-65%
50-55%
Specificity
>99%
99%
>99%

 

When Should this Test be Ordered?

When Should NMO Test be Ordered?

 

What is Neuromyelitis Optica (NMO)?

Neuromyelitis optica (NMO) is an inflammatory, demyelinating disease of the central nervous system. It is characterized by severe relapsing attacks of optic neuritis and transverse myelitis which, unlike the attacks in multiple sclerosis, commonly spare the brain in the early stages.

The spectrum of NMO was traditionally restricted to the optic nerves and the spinal cord. However, since Mayo Clinic physician Dr. Vanda Lennon discovered an antibody called aquaporin-4 (AQP4), which targets the water channel on astrocytes, a much broader category called NMO spectrum disorders has evolved and can include patients with:

  • Single or recurrent episodes of optic neuritis who test positive for AQP4-IgG
  • Single or recurrent episodes of transverse myelitis who test positive for AQP4-IgG

The Importance of Early and Accurate Diagnosis

Differentiating Between NMO and Multiple Sclerosis

Although NMO spectrum disorders have very similar clinical and radiologic characteristics to multiple sclerosis (MS), the diseases are treated very differently.

  • A majority of NMO patients, typically women, are initially misdiagnosed with MS
  • NMO is treated by immunosuppressant therapy and MS is treated by immunomodulation therapy, which may worsen NMO

Stop the Attacks, Stop the Disability

Unlike MS, the neurological disability caused by NMO spectrum disorders are based on the number of attacks rather than a progressive phase of the illness.

  • Initiating therapy early in the course to eliminate recurrence of attacks will minimize patient disability
  • If not treated appropriately, within 5 years, 50% of NMO patients lose functional vision in at least 1 eye or are unable to walk

How Does the Aquaporin-4-IgG Cell-Binding Assay Work?


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References

  1. Waters PJ, et al. Serologic diagnosis of NMO: a multicenter comparison of aquaporin-4-IgG assays. Neurology. 2012 Feb 28;78(9):665-71

A Patient’s Story

A Patient Story, Courtney Engel

Courtney uses her violin to continue her fight against a serious autoimmune disease

Word of the recital had spread and Courtney’s friends and admirers responded enthusiastically. It was her first time on stage as a soloist since she’d suffered a devastating loss of vision after developing neuromyelitis optica (NMO).

Learn more...


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