Autoimmune profile updates
Eye on Innovation
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As a leader in autoimmune neurology, Mayo Clinic is always looking to improve diagnostic testing. Studies have shown that certain antibodies may not be as clinically relevant to autoimmune testing as previously thought, and including those antibodies in autoimmune profiles increases the risk of false positives in what are already challenging diagnoses. Based on that, Mayo Clinic Laboratories is adjusting a number of its autoimmune profiles by removing certain antibodies from them.
The primary changes to the autoimmune evaluations include complete removal of striational antibodies and anti-calcium channel antibodies. Although N-type calcium channel antibodies sometimes accompany P/Q-type, and can be associated with cancer, it was determined, overall, that including N-type does not add sufficient value. In addition, P/Q-type antibody will only be used in the Lambert-Eaton syndrome and movement disorders evaluations. Alpha-3 ganglionic acetylcholine receptor antibody will be included in the autonomic dysfunction evaluations only.
According to Andrew McKeon, M.B., B.Ch., M.D., one of the directors of Mayo Clinic's Neuroimmunology Laboratory, these updates are being made on a solid foundation of research. "We've published extensively on biomarkers and their clinical utility, including the antibodies that we're now eliminating," he says.
"There are papers we have published dating back several years related to the striational, P/Q, N, and alpha-3 antibodies that spell out the limitations of those tests outside of specific neurologic phenotypes."
Although it's been known for some time that these antibodies are less specific than other IgG biomarker offerings, Mayo Clinic Laboratories' approach has been to include more biomarkers, rather than fewer, because they can contribute to building a picture of a patient's condition. Mayo Clinic Laboratories has included specific, directed comments for physicians when these antibodies are positive to ensure results are acted upon with caution. Over time, however, feedback from providers has made it clear that they would prefer more clarity in the test results.
"These are not radical changes by any means. This is something that's been evolving over time," Dr. McKeon says.
"We've collected data to drill down on the significance of test results in different phenotypes. Based on that, we're recalibrating our profiles to make sure what's in there is of the highest clinical utility for providers."
For the last several years, Mayo Clinic Laboratories has worked to develop phenotype-specific profiles tailored to a patient's presentation. This makes test ordering easier, and it improves positive-predictive value because the antibody is found in the appropriate clinical context that will have a meaningful impact on diagnosis and treatment. A decade ago, when the field of autoimmune neurology was less complex, the common thought was that one test could investigate all relevant neuronal antibodies and rule in or out an autoimmune etiology. The explosion of antibody discovery in the last 10 years, however, has made that approach untenable, as evidenced by the often confusing results of current antibody tests. Updating the autoimmune profiles is the next logical step in phenotype-specific testing. These changes will increase the profiles' positive predictive value and specificity, and will provide neurologists with greater confidence in an autoimmune diagnosis.
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