TBK1 and frontotemporal dementia: The FTD‐ALS causative gene TBK1 contributed to about 1.3% ALS, 3%–4% ALS‐FTD, and <1% FTD with TDP‐43 pathology (Nguyen, Van Broeckhoven, & van der Zee, 2018), of whom great clinical heterogeneity was presented.