TBK1 and mild neurocognitive disorder: TBK1 was the most frequently mutated gene in genetic-positive PPA-MND patients (41.2%), in accordance with evidence suggesting that loss of function mutations in this gene display a broad phenotypic heterogeneity - encompassing bvFTD, PPA (both PNFA and SD) (Le Ber et al., 2015; Lamb et al., 2019; Swift et al., 2021), MND (and, especially, predominant-UMN phenotypes) (Van Mossevelde et al., 2016; Gómez-Tortosa et al., 2017) and atypical parkinsonisms (Wilke et al., 2018; Seibert et al., 2021; Swift et al., 2021).