NEFL and amyotrophic lateral sclerosis: Among the different isoforms, Neurofilament light-chain (NF-L), the most abundant and soluble form detected in biofluids [18], was investigated in a variety of neurological disorders, such as Multiple Sclerosis (MS), AD, frontotemporal dementia (FTD), Amyotrophic Lateral Sclerosis (ALS), atypical parkinsonian disorders (APD), and traumatic brain injury (TBI) [17,19,20,21,22,23,24,25], showing the non-specific nature of axonal damage and its contribution in disease progression.