Despite discrepancies among some findings as noted above, which may be caused by differences in cohort sizes, matrices (i.e., CSF, plasma, serum), neurofilament types (i.e., NfL or pNfH), assay sensitivity, and analytical rigor, neurofilaments are leading prognostic biomarkers for ALS. This evidence concerns the gene NEFL and amyotrophic lateral sclerosis.