C9orf72 and amyotrophic lateral sclerosis: A hallmark pathological feature of C9ORF72-associated ALS/FTD is the aberrant accumulation of dipeptide repeat proteins (DPRs), particularly poly(glycine-arginine) [poly(GR)], which are generated through repeat-associated non-AUG (RAN) translation of the expanded G4C2 repeats (5, 6, 7).