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Updated: Mar 23, 2026

Real-Time Fluorescent Measurement of Synaptic Functions in Models of Amyotrophic Lateral Sclerosis
Published on: July 16, 2021
SMN1 gene duplications are associated with sporadic ALS
H M Blauw1, C P Barnes, P W J van Vught
1Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands.
Objective:
To investigate the role of SMN1 and SMN2 copy number variation and point mutations in amyotrophic lateral sclerosis (ALS) pathogenesis in a large population.
Methods:
We conducted a genetic association study including 847 patients with ALS and 984 controls. We used multiplexed ligation-dependent probe amplification (MLPA) assays to determine SMN1 and SMN2 copy numbers and examined effects on disease susceptibility and disease course. Furthermore, we sequenced SMN genes to determine if SMN mutations were more prevalent in patients with ALS. A meta-analysis was performed with results from previous studies.
Results:
SMN1 duplications were associated with ALS susceptibility (odds ratio [OR] 2.07, 95% confidence interval [CI] 1.34-3.20, p = 0.001). A meta-analysis with previous data including 3,469 individuals showed a similar effect: OR 1.85, 95% CI 1.18-2.90, p = 0.008). SMN1 deletions and SMN2 copy number status were not associated with ALS. SMN1 or SMN2 copy number variants had no effect on survival or the age at onset of the disease. We found no enrichment of SMN point mutations in patients with ALS.
Conclusions:
Our data provide firm evidence for a role of common SMN1 duplications in ALS, and raise new questions regarding the disease mechanisms involved.
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