C9orf72 and frontotemporal dementia: To do so, we assembled an FTD cohort with a neuropathological diagnosis of frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP), with an approximately equal number of cases having an expanded G4C2 repeat in the C9ORF72 gene, GRN mutations or no known FTD-causative mutation (Supplementary Table S1).