A blood test developed by researchers at the University of Miami can now estimate when symptoms of amyotrophic lateral sclerosis (ALS) will emerge in people at genetic risk — often years before the first sign of muscle weakness. Published in Nature Medicine in July 2026, the study identifies a panel of 19 blood proteins that predict the timing of ALS onset with an average error of about 18 months.
The finding, funded in part by the National Institutes of Health, could reshape how clinical trials for ALS are designed and open the door to true preventive treatment for one of neurology’s most devastating diseases.
Why Predicting ALS Onset Matters
ALS is a progressive neurodegenerative disease that destroys motor neurons in the brain and spinal cord. Roughly 5,000 Americans are diagnosed each year, and average survival after diagnosis is two to five years, according to the ALS Association. About 10 percent of cases are familial, linked to inherited mutations in genes such as SOD1, C9orf72, and FUS.
For decades, researchers have known that pathological changes begin long before the first cramp or twitch. But without a way to time the arrival of symptoms, clinicians could not confidently enroll high-risk carriers in trials of drugs meant to delay or prevent the disease. The new blood-based biomarker changes that calculus.
Inside the Study
The team, led by neurologist Michael Benatar, M.D., Ph.D., and biostatistician Joanne Wuu, Sc.M., drew on the long-running Pre-fALS observational study, which tracks people carrying ALS-causing gene mutations before they develop symptoms. From 137 participants, 33 eventually progressed to clinical ALS or the related condition frontotemporal dementia during the observation period.
Researchers analyzed more than 5,000 circulating proteins from stored blood samples using high-throughput proteomics. Ninety-two proteins showed significant pre-symptomatic changes. A refined 19-protein panel — anchored by neurofilament light chain (NfL), a marker of axonal injury — delivered the sharpest predictive accuracy across windows ranging from six months to five years before symptom onset.
Crucially, the model was validated against blood samples in the UK Biobank, suggesting the biomarkers may work beyond the genetically enriched cohort studied at Miami. Dr. Benatar summarized the result: “These biomarkers give us a far better idea of the timing, allowing us to estimate the time to symptom onset with an average error of about 18 months.”
How Neurofilament Light Chain Fits In
NfL is a structural protein released into blood and cerebrospinal fluid when nerve axons are damaged. Elevated NfL levels have already been validated as a marker of neurodegeneration in multiple sclerosis, Alzheimer’s disease, and traumatic brain injury. In ALS, NfL rises months to years before overt weakness, and it is already used to monitor treatment response for the gene therapy tofersen, which received accelerated FDA approval in 2023 for SOD1-linked ALS.
What the new study adds is context. NfL alone tells clinicians that neurons are dying; the broader 19-protein signature tells them approximately when clinical disease will manifest. Combined, the biomarkers can help match the right patient to the right trial at the right window.
Enabling Preventive ATLAS Trials
The finding lands at a moment when gene-targeting ALS therapies are moving upstream. The ATLAS trial, currently underway, tests tofersen in people who carry SOD1 mutations but have not yet developed symptoms. Enrolling participants close to their expected onset — rather than years too early or too late — is essential to detecting a real prevention effect within a realistic trial timeframe.
Beyond SOD1, similar strategies are being explored for C9orf72 and FUS mutation carriers. Research published in The Lancet Neurology has shown that antisense oligonucleotide platforms can silence disease-driving genes; the missing piece has been identifying who is close enough to onset to benefit. The Miami-led biomarker panel begins to fill that gap.
Broader Implications for Neurodegenerative Disease
The approach echoes a broader shift across neurology toward pre-symptomatic detection. Blood-based tests for phosphorylated tau (p-tau217) are transforming early Alzheimer’s diagnosis, and alpha-synuclein seed amplification assays are advancing pre-motor Parkinson’s research. In each case, the ability to identify disease before irreversible neuronal loss creates a wider therapeutic window.
Researchers caution that the ALS biomarker panel is not yet a screening test for the general population. It was developed in people already known to carry ALS-causing gene mutations, and its performance in sporadic ALS — which accounts for the other 90 percent of cases — will require additional validation. Studies extending the analysis to broader biobank cohorts are already underway.
What Patients and Families Can Do Today
For families with a known history of ALS, genetic counseling is the first practical step. Board-certified counselors can explain the implications of testing for SOD1, C9orf72, and other ALS-linked variants, and can connect interested individuals with pre-symptomatic research programs such as Pre-fALS or the Genetic Frontotemporal Dementia Initiative.
Lifestyle factors do not cause familial ALS, but general neurological health matters. Reviews in JAMA Neurology associate regular aerobic exercise, Mediterranean-style diets rich in omega-3 fatty acids, and control of vascular risk factors with lower rates of neurodegenerative disease progression. Whether any of these modify ALS onset in mutation carriers remains an active research question.
Anyone experiencing new muscle weakness, twitching, difficulty speaking or swallowing, or unexplained falls should consult a neurologist. Early evaluation matters because current disease-modifying therapies — including riluzole, edaravone, and tofersen for SOD1-linked disease — appear most effective when started early in the clinical course.
The Road Ahead
The University of Miami team plans to expand the biomarker panel using data from ongoing longitudinal cohorts and to test whether the same proteins predict progression rate after symptoms begin. If confirmed, the panel could become a routine tool for enrolling and monitoring participants in the next generation of ALS prevention trials.
For a disease long defined by therapeutic frustration, the ability to see it coming — and to intervene before it takes hold — represents a meaningful shift. As Dr. Benatar and colleagues note in their paper, predicting onset is not a cure. But it is the prerequisite for one.
Disclosure: This content is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider before making changes to your health regimen.