C9orf72 and amyotrophic lateral sclerosis: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) cases with C9orf72 mutation show characteristic nuclear foci of the sense and antisense repeat RNA ((G4C2)n and (C4G2)n) as well as neuronal inclusions resulting from non‐canonical translation of the repeat RNA in all reading frames (DeJesus‐Hernandez et al, 2011; Renton et al, 2011; Ash et al, 2013; Mori et al, 2013; Edbauer & Haass, 2016).