In a cohort in which the diagnostic certainty was increased based on genetic, neuropathological, or CSF AD biomarker data or, in the case of FTLD, on the co-occurrence of ALS, given the differences in CSF NFL levels between patients with FTLD (showing the highest levels), patients with AD (intermediate levels), and cognitively normal controls (lowest levels), CSF NFL was able to correctly assign 85.2% of patients to each of the three categories (Alcolea et al., 2017). This evidence concerns the gene NEFL and amyotrophic lateral sclerosis.