C9orf72 and frontotemporal dementia: For example, post-mortem examination of brain tissue in patients with an expanded ‘GGGGCC’ repeat in the 5’ region of C9orf72 ALS/FTD, revealed multiple potential pathogenic RNA species: RNA that had been stalled at repeat locations, RAN proteins, antisense transcription of repeat regions and alternative splicing of intron 1 containing the repeat [48].