C9orf72 and amyotrophic lateral sclerosis: Histopathological analysis of the most common genetic subtype of ALS linked with expansion of GGGGCC hexanucleotide in the C9orf72 gene, in addition to cytoplasmic TDP-43 aggregates, shows p62-positive deposits formed by pathological dipeptide repeat proteins (DPRs), which is absent in other ALS models (Ramos-Campoy et al. 2018; Mead et al. 2023).