C9orf72 and amyotrophic lateral sclerosis: However, even these pathological hallmarks of C9orf72‐linked ALS remain controversial, since O'Rourke et al. showed RNA foci and DPR aggregation did not influence motor behaviour, while in other models, DPR formation, but no RNA foci, is present along with a severe motor phenotype (Riemslagh et al., 2021).