While it is possible that all three of these mechanisms contribute towards disease, studies have shown that C9orf72 knockout models fail to recapitulate FTD or MND phenotypes, suggesting that even though haploinsufficiency may potentiate toxic RNA and DPR gain-of-function it is unlikely to precipitate the disease in its own right [4, 10]. This evidence concerns the gene C9orf72 and frontotemporal dementia.