Neurofilament light chain (NfL), a structural protein found in axons, is released into the CSF and plasma at levels proportional to the degree of ongoing axonal damage, thereby serving as a biomarker of neurodegeneration in neurological conditions, including ALS (Gaetani et al., 2019; Verde et al., 2019). This evidence concerns the gene NEFL and amyotrophic lateral sclerosis.