C9orf72 and frontotemporal dementia: ALS/FTD‐causing mutations in C9orf72, OPTN, SQSTM1, TBK1, UBQLN2, and VCP are linked to the ubiquitin‐proteasome system (UPS) and autophagy, which can clear aggregated and phase‐separated proteins, suggesting the proteostasis system is of particular importance at least in genetic ALS/FTD (Gitcho et al, 2009; Deng et al, 2011; Hipp et al, 2019).