One in 10 of all cases of ALS (and of the pathologically-linked syndrome of frontotemporal dementia) are associated with a hexanucleotide repeat expansion (HRE) in C9orf72, which contributes to neuronal death via haploinsufficiency, dipeptide repeat protein production and expanded RNA species forming RNA foci (De Jesus-Hernandez et al., 2011; Mori et al., 2013a, b; Cooper-Knock et al., 2014) and leads to sequestration of the nuclear export adaptor SFSR1 and impaired DNA repair mechanisms (Hautbergue et al., 2017; Walker et al., 2017). This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.