C9orf72 and frontotemporal dementia: Our study highlighted this emerging research avenue in drug discovery for these devastating diseases consolidating ER-mitochondria signalling as a common pathogenic mechanism, affecting to the most frequent familial form of ALS/FTD; pathogenic C9orf72 repeat expansion account for around 40% and 25% of familial ALS or FTD respectively, and for around 6% of sporadic cases in both as well.