MAPT and amyotrophic lateral sclerosis: TAR DNA-binding protein of 43 kDa (TDP-43), encoded by TARDBP gene, was originally described as the major component of ubiquitin-positive neuronal inclusions in nearly all (97%) amyotrophic lateral sclerosis (ALS) cases and in nearly 50% of patients with frontotemporal degeneration (FTLD-TDP), while most of the remaining cases have tau pathology (FTLD-tau).