In 2011, a major discovery connecting ALS and FTD was made that the expanded GGGGCC hexanucleotide repeat of the C9orf72 gene is an important genetic cause for ALS/FTD, accounting for roughly 40% of familial ALS patients, 25% of familial FTD patients and as high as 88% in familial ALS/FTD patients (DeJesus-Hernandez et al., 2011). This evidence concerns the gene C9orf72 and frontotemporal dementia.