C9orf72 and amyotrophic lateral sclerosis: With respect to C9orf72 ALS/FTD cellular phenotypes, it is notable that pathological features examined in postmortem human tissues, such as the formation of nuclear RNA foci and the generation of DPR proteins, are most prominent in neurons compared to neighboring astrocytes and microglia (Gendron et al., 2013; Mackenzie et al., 2013; Mizielinska et al., 2013; DeJesus-Hernandez et al., 2017; Saberi et al., 2018; Rostalski et al., 2019).