C9orf72 and amyotrophic lateral sclerosis: Poly‐GR is an unfolded dipeptide repeat that can never adopt a native state and accumulates inside the nucleolus; poly‐GR originates from the GGGGCC (G4C2) repeat expansion in a non‐coding region of the C9ORF72 gene, which represents the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (Freibaum et al, 2015).