Interestingly, four patients with TBK1 FTD–ALS from French–Portuguese cohort predominantly had language symptoms [25], secondarily developing ALS, which was similar to the p.E653fs mutation carriers in this study, suggesting that we should screen the TBK1 gene in patients who were clinically diagnosed as SD-ALS. Here, TBK1 is linked to amyotrophic lateral sclerosis.