Publications analysing post-mortem tissue of C9-ALS/FTD cases most commonly reported (i) reduced levels of C9orf72 proteins (n = 5), (ii) DPR aggregates/ toxicity (n = 24), (iii) abundant RNA foci (n = 10) and (iv) brain region-specific neuronal loss (n = 5). Here, C9 is linked to frontotemporal dementia.