Simple and Accessible Blood Test to Enable Faster Diagnosis of Rare Autoimmune Disease

Myasthenia gravis, a rare autoimmune disease characterized by "severe muscle weakness," affects approximately one in 5,000 people, predominantly women under 40 and men over 60. Symptoms include drooping eyelids, double vision, difficulty speaking, chewing, breathing, and controlling limbs. In severe cases, it can be life-threatening. Current blood tests for myasthenia gravis target one of three antibodies and can take weeks to yield results. In 15 to 50% of cases, patients with the disease have negative antibody tests. Due to symptom similarities with other neurological conditions like stroke or multiple sclerosis, accurate diagnosis often takes up to two years. Researchers have now identified a universal biological marker that could lead to a quicker, more accessible diagnostic test for myasthenia gravis.

The research team at the University of Alberta (Edmonton, Canada) employed advanced proteomics to identify significantly higher blood levels of the protein fibrinogen in myasthenia gravis patients, compared to healthy individuals and those with rheumatoid arthritis. They analyzed blood samples from 31 myasthenia gravis patients, 30 healthy controls, and 18 rheumatoid arthritis patients, applying various proteomic techniques. These analyses revealed that fibrinogen levels were about 1,000 times higher in all myasthenia gravis patient samples. They replicated these findings with other methods and further validated the results using blinded samples.

The reason behind the elevated fibrinogen levels in myasthenia gravis patients remains unclear, though it is suspected to be related to chronic inflammation. Further research is necessary to fully understand the underlying mechanisms. Previously, the team had identified other myasthenia gravis biomarkers using metabolomics, but such techniques are limited to major medical centers. The newly identified biomarker, detectable with simpler technology, could potentially be used in smaller hospitals and rural centers. The researchers also anticipate that this biomarker might help monitor patients’ response to treatment in the future. Plans are underway for a larger study to confirm these findings and to develop a simpler, faster diagnostic test.

“We have found a simple and universal biomarker for all types of myasthenia gravis regardless of the stage of the disease, so I hope we can use this methodology to diagnose patients much quicker,” said principal investigator and neurologist Zaeem Siddiqi.

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University of Alberta