Since FUS, TDP-43, hnRNPA2, TAF15 and EWS each form cytoplasmic aggregates when ectopically expressed in yeast—much like naturally occurring yeast prion proteins—it has been straightforward to monitor how specific ALS-linked mutations alter the proteins’ intrinsic propensity to aggregate and exert toxicity, especially when coupled with in vitro aggregation assays. The gene discussed is EWSR1; the disease is amyotrophic lateral sclerosis.