Reductions in SV2 and the size of readily releasable pool of vesicles were also reported in C9orf72-ALS patient-derived induced pluripotent stem cell (iPSC) cortical neurons [36, 57], but, while we observed reduced SV2 in hippocampal neurons in vitro after C9orf72 knockdown, and a C9orf72 gene dosage-dependent decrease in vivo in the hippocampus of C9orf72-HET and C9orf72-KO mice (Figs. 4, 5), we did not observe this in post-mortem hippocampus from C9ALS/FTD patients (Fig. 6). Here, C9orf72 is linked to frontotemporal dementia.