C9orf72 and frontotemporal dementia: Although the formation of polyG in OPML and OPDMs has not yet been elucidated, in the C9ORF72-associated amyotrophic ALS/FTD, translation of the polyglycine-alanine dipeptide repeat (polyGA DPR) protein occurs because of G4C2 repeats located in the first intron of the C9ORF72 gene (Tabet et al., 2018).