C9orf72 and amyotrophic lateral sclerosis: The GGGGCC (G4C2)repeat expansion in the non-coding region of the C9orf72 protein is the most common cause of sporadic and familial forms of amyotrophic lateral sclerosis (ALS) and frontal temporal dementia (FTD), (DeJesus-Hernandez et al., 2011; Renton et al., 2011).