Breakthrough muscle biopsy test could lead to earlier ALS diagnosis, researchers say

There soon could be a breakthrough on testing for amyotrophic lateral sclerosis, better known as ALS. Researchers say a muscle biopsy test could lead to an earlier diagnosis of the deadly disease.

Hiroshima University scientists conducted a study of 10 people who had ALS at the time of their death and 12 who did not. Researchers say that all of the ALS patients had TDP-43 accumulations in their intramuscular nerve bundles, while those without ALS did not.

“TDP-43 is a protein that plays a key role on motor neurons, and accumulation of TDP-43 may be a biomarker for early diagnosis of ALS,” says researcher Hirofumi Maruyama, a professor at the Graduate School of Biomedical and Health sciences at Hiroshima, in a statement.

Researchers then studied 114 patients who underwent a muscle biopsy and did not have a family history of ALS. Of those 114 patients, 71 had evidence of intramuscular nerve bundles and 43 did not. Among the 71, 33 had axonal TDP-43 accumulations in their nerve bundles and were all later diagnosed with ALS. Of the 43 patients without nerve bundles, three were later diagnosed with the disease.

Accumulation of TDP-43 with ALS patientsTDP-43 accumulation was evident in intramuscular nerve bundle from ALS patient. (Credit: Takeshi Kurashige, Kure Medical Center)

“Results of this dual case-control and cohort study suggest that axonal TDP-43 accumulations may be characteristic for patients with ALS, and consequently may be a novel diagnostic biomarker for ALS,” says Maruyama. “Early diagnosis enables patients to initiate prompt treatment. We aim to prevent progression of ALS and will continue research into developing new medication.”

In previous research on mice, scientists found a critical function of TDP-43 in axons, which is the part of the neuron that sends signals to other neurons. According to the study, researchers believed that TDP-43 accumulation in muscular nerve bundles could be an early predictor of ALS.

“It is difficult to diagnose ALS in its early stages because there is not a known biomarker,” says Maruyama. “Muscle is possible to biopsy, and transitive response DNA-binding protein 43 accumulates in the peripheral nerves inside muscle.”

The study is published in JAMA Neurology.

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