The most complete meta‐analysis on disease (n = 16 studies) comparison demonstrated higher blood NfL levels in individuals with ALS (n = 930) if compared to cognitively unimpaired controls (n = 593) with an effect size of 9.64 (95% CI 6.65–13.99) (Forgrave et al., 2019). This evidence concerns the gene NEFL and amyotrophic lateral sclerosis.