Third, although model systems often characterize the effects of individual C9orf72-pathomechanisms, it may be difficult to relate these findings to iPSC-derived neurons or postmortem tissue from C9orf72-ALS cases, which may exhibit concurrent signs of RNA toxicity, DPRs, and C9orf72 downregulation. The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.