Genetic mutations in TARDBP, which encodes TDP-43, were first found to be a cause of sporadic and familial ALS and FTD disorders, providing a direct link between TDP-43 and disease pathogenesis.37,38 However, TARDBP mutations are a rare cause of ALS and FTD, accounting for only 1% of ALS cases and <1% of FTD cases.39 TDP-43 is found in both genetic and sporadic FTD and ALS. This evidence concerns the gene TARDBP and amyotrophic lateral sclerosis.