C9orf72 and frontotemporal dementia: The most common genetic determinant in the present bvFTD cohort was MAPT mutations, and C9orf72 repeat expansions were identified with a low frequency, which differ from reports derived from Europe and America (Greaves and Rohrer, 2019; Oijerstedt et al., 2019; Ramos et al., 2019b, 2020), but are similar to previous studies involving Chinese patients with FTD (Shi et al., 2016; Tang et al., 2016; Che et al., 2017; Jiang et al., 2021).