Seeing a simple tube of blood decide the future of a patient suffering from amyotrophic lateral sclerosis (ALS) was until recently science fiction. No reliable biomarker, no blood test to confirm Charcot disease, only months of tests and waiting. An American laboratory today presents a blood test which promises to change this reality, with an announced accuracy of 97%.
This rare neurodegenerative disease progressively destroys the motor neurons responsible for movements, speech or breathing. The incidence is estimated at 1.6 cases per 100,000 adults, or approximately 7,000 people living with ALS in France. However, the diagnosis remains long and uncertain: up to 68% of patients are initially misdirected, and wait more than a year before obtaining the correct characterization. A deadline that this new test wants to drastically shorten.
A 97% blood test for Charcot disease
Wyoming-based nonprofit Brain Chemistry Labs has developed a blood test that analyzes microRNAs – short fragments of RNA that regulate gene expression. Researchers studied 788 blood samples, including 393 patients with
amyotrophic lateral sclerosis (ALS) and 395 age- and sex-matched healthy controls. The test identifies the presence of the disease from a single blood test, with a sensitivity of 97% (capacity to give a positive result in the event of illness) and a specificity of 93% (capacity to give a negative result in the absence of disease), and works as well for sporadic, majority forms as for familial forms of the disease*.
This test aims first of all to reduce the diagnostic wandering that affects Charcot disease. “ALS patients are woefully underdiagnosed“says Dr. Paul Alan Cox, co-founder of Brain Chemistry Labs.”This is why, as a non-profit organization, we have tirelessly pursued the development of this diagnostic test“, he declared. His colleague Sandra Banack insists on access: “We are seeking to identify a diagnostic company to make this test commercially available“, she explained during an international symposium. According to her, the analysis could cost less than 150 dollars, or around 140 euros, and be offered within one to two years if the validations are confirmed.
How these tests change for ALS patients
For patients, the issue is very concrete: shortening the time before specialist advice and access to treatments or clinical trials. “For ALS, which often leads to death between two and five years after symptom onset, a one-year delay in diagnosis is simply unacceptable“, explains Dr. Rachael Dunlop, first author of the study published in Molecular Neurobiology. For his part, neurologist Ahmad Al Khleifat, from King’s College London, speaks of a “fantastic” result, estimating that “the test works well to distinguish people with and without ALS”, cited by New Scientist magazine.
This microRNA test is part of a wave of blood biomarkers for Charcot disease. In September, a study published in Nature Medicine identified, out of nearly 3,000 proteins, a signature capable of announcing ALS ten years before the first symptoms. “We have always assumed that ALS is a rapid disease that begins 12 to 18 months before symptoms appear.“, recognized the neurologist Alexander Pantelyat at the origin of the study.
Together, these approaches point to a future where ALS would be detected much earlier, with simple tests based on a blood test.