In 2011, a trio of teams [8,9,10] discovered a GGGGCC (G4C2) nucleotide repeat expansion mutation in the first intron of the chromosome 9 open reading frame 72 (C9orf72) gene as the most frequent genetic cause in up to 35–45% of familial ALS, 5–20% of sporadic ALS, 15–25% of familial FTD, and 6–7% of sporadic FTD patients [11]. The gene discussed is C9orf72; the disease is frontotemporal dementia.