Neurological Test Distinguishes MS from Other Demyelinating Diseases

Representing the first of its kind in the United States, a test from the Mayo Clinic, Rochester, Minn, is designed to help patients who have recently been diagnosed with an inflammatory demyelinating disease (IDD) but are unsure of the exact disorder.

Neurologic-related diseases commonly affect the brain, optic nerves, and spinal cord. The MOG-IgG test is appropriate for diagnosing IDDs with characteristics similar to neuromyelitis optica spectrum disorders (NMOSD), including optic neuritis (single or bilateral) and transverse myelitis.

The test can also help diagnose acute disseminated encephalomyelitis (ADEM) and neuromyelitis optica, and is able to predict a relapsing disease. Furthermore, the test allows distinction of ADEM, NMOSD, optic neuritis, and transverse myelitis from multiple sclerosis (MS) early in the course of the disease.

The test uses live cells to identify patients who are positive for an antibody to myelin oligodendrocyte glycoprotein (MOG).

Sean Pittock, MD, Mayo Clinic.

“From our years of research, we have learned that if patients test positive for MOG antibodies, it generally indicates that it’s not classical MS,” says Sean Pittock, MD, a Mayo Clinic neurologist and director of the Mayo Clinic neuroimmunology laboratory. “More important, some MS treatments have been reported to worsen the disease of patients diagnosed with an IDD that is not classical MS.

“While many IDDs that mimic MS are rare, correct and early diagnosis allows for early immunotherapy with immunosuppressants, rather than disease-modifying agents that are commonly used in treating MS,” says Pittock.

The researchers also found that persistence of the MOG antibody is associated with disease relapses, thus warranting relapse-preventing immunotherapy.

Andrew McKeon, MB, BCh, MD, Mayo Clinic.

“We’ve learned that if patients are positive for MOG antibodies, and they have an attack (such as optic neuritis), and they persistently remain positive [for the MOG antibodies] when tested 6 to 12 months later, they have a higher likelihood for a relapse,” says Andrew McKeon, MB, BCh, MD, a clinical biochemist and codirector of Mayo’s neuroimmunology laboratory. “Certain drugs will prevent disease relapses and may reduce disability progression, so this diagnostic information will help healthcare providers and their patients with treatment options.”

Pittock says that patients suddenly presenting with vision loss, significant disc edema, or recurrent optic neuritis should consider testing for both MOG and AQP4 antibodies.

Discovered at Mayo Clinic in 2004, the aquaporin-4 (AQP4) antibody was the first biomarker associated with inflammatory demyelinating diseases. “The AQP4 test is a standard test in the evaluation of any patient undergoing an MS workup,” says Pittock. “And now, this second antibody—MOG—will be helpful because the presence of MOG antibodies indicates that a patient doesn’t have MS.”

McKeon agrees and adds, “the combination of these two tests—the AQP4 and MOG antibodies —allows for the most comprehensive evaluation for patients recently diagnosed with demyelinating diseases.”

The test is performed with serum, not spinal fluid—as some may assume. “Testing for either AQP4 or MOG antibodies in cerebrospinal fluid (CSF) alone will miss positive patients; therefore, MOG antibody testing is not offered on CSF.”

The Mayo researchers worked extensively with Patrick Waters, PhD, codirector of the University of Oxford autoimmune neurology diagnostic laboratory.

“The Mayo Clinic neuroimmunology laboratory has been developing this test in the United States for 3 years,” says Pittock. “We’ve collaborated with experts at Oxford University in MOG antibody testing to optimize our assay.”

Both the MOG and AQP4 tests are available to Mayo Clinic patients and healthcare providers worldwide through Mayo Medical Laboratories, the global reference laboratory of Mayo Clinic.