NEFL and amyotrophic lateral sclerosis: •TDP-43 showed colocalization in ALS motor neurons with mutants or WT-SOD1.•TDP-43 showed colocalization in ALS's MNs and controls with STAUFEN.•The frequency of SGs and P-bodies in ALS's MNs were higher than controls and showed colocalization with TDP-43.•NFL mRNA processing in ALS's MNs is severely altered by TDP-43.