Test in Focus
Stiff-person syndrome is a spectrum of disorders whose most severe form is associated with uncontrollable muscular rigidity and spasms that can be caused by an autoimmune response. In this "Test in Focus" episode of the "Answers From the Lab" podcast, Andrew McKeon, M.B., B.Ch., M.D., discusses Mayo Clinic Laboratories' unique assay based on the four known antibodies that can be present in individuals on the spectrum — including patients with the severe PERM phenotype.
"The idea is to include all antibodies pertinent to stiff-person syndrome but not to other movement disorders," Dr. McKeon says. "Capturing all of the stiff-person spectrum will aid in confirming diagnosis because there can be clinical overlap in how these disorders present."
Available for both serum and cerebral spinal fluid, the assay detects GAD 65, anti-glycine receptor, DPPX and amphiphysin antibodies.
Mayo Clinic Laboratories recommends serum evaluation for individuals suspected of having classic stiff-person syndrome. A CSF test is appropriate if the serum test is negative but clinical suspicion remains. For patients who present with myoclonus and encephalopathy — symptoms associated with the PERM phenotype — both serum and cerebral spinal fluid evaluation are recommended.
The test results can help guide patient treatment.
"A positive test result could mean there is an occult cancer that needs to be looked at," Dr. McKeon says. "In terms of treatment, all four antibodies respond to immune therapy to varying degrees. In particular, the glycine receptor antibody, which is very specific for a diagnosis of PERM, seems to be immune therapy responsive."
The laboratory report includes guidance for appropriate immune therapy and cancer evaluations.
Listen to learn more about how the stiff-person assay can provide comprehensive results to guide the treatment of patients with stiff-person syndrome.
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Evaluating patients with suspected stiff-person syndrome (classical or focal forms, such as stiff-limb or stiff-trunk) and progressive encephalomyelitis with rigidity and myoclonus using spinal fluid specimens.
SPPS | Stiff-Person Spectrum Disorders Evaluation, including Progressive Encephalomyelitis with Rigidity and Myoclonus, Serum
SPPC | Stiff-Person Spectrum Disorders Evaluation, including Progressive Encephalomyelitis with Rigidity and Myoclonus, Spinal Fluid
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