So far, at least 100 variants in the TBK1 gene, including loss of function variants, in-frame deletions of single amino acids, and missense variants, have been reported in ALS, FTD, or ALS-FTD patients, thus making TBK1 the third or fourth most frequent genetic cause of ALS and FTD [12]. This evidence concerns the gene TBK1 and amyotrophic lateral sclerosis.