In this cohort of 130 patients (56 FTD, 58 ALS and 16 FTD-ALS), we performed C9orf72 hexanucleotide repeat expansion analysis, whole exome sequencing and measurement of “classical” (Aβ42, total tau and phospho-tau) and novel (TDP-43) CSF biomarkers and plasma progranulin. Here, C9orf72 is linked to frontotemporal dementia.