C9orf72 and frontotemporal dementia: Although most genetic FTD is accounted for by mutations in 3 genes, progranulin (GRN), microtubule-associated protein tau (MAPT), and chromosome 9 open reading frame 72 (C9orf72) (Moore et al., 2020), there are a number of rarer causes including mutations in TANK-binding kinase 1 (TBK1), valosin-containing protein, and TAR DNA-binding protein 43 (Greaves and Rohrer, 2019).