Taking advantage of red cells, plasma and DBS extracted from the same blood samples from healthy controls and patients with amyotrophic lateral sclerosis (ALS), a clinically heterogeneous and invariably fatal neurodegenerative disorder, we have looked at whether DBS-based Nf-L measurements maintain the same discriminatory power reported using plasma assays where Nf-L differentiates healthy from affected individuals as well as fast versus slow progressing ALS patients. This evidence concerns the gene NEFL and amyotrophic lateral sclerosis.