C9orf72 and amyotrophic lateral sclerosis: Accordingly, the decreased expression of C9orf72 protein isoforms, the formation of nuclear RNA agglomerates (foci), and the aggregation of C9-DPRs have been recorded in tissues from patients and in cellular and animal systems modeling the disease [3,4], supporting the idea that a combination of these events underlies neuron degeneration in ALS and FTD.