We re-analysed two human post-mortem brain datasets: one from FTD patients with either Tau (FTD-Tau) or TDP-43 (FTD-TDP) pathology (37) and the second from ALS patients with either C9orf72 mutations (c9ALS) or without known mutations (sALS) where both groups should have TDP-43 pathology (38). The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.