SETX and amyotrophic lateral sclerosis type 4: To confirm the relevance of SETX function to nucleolus liquidity in a more physiologically relevant cell type, we obtained an induced pluripotent stem cell (iPSC) line from an ALS4 patient carrying the pathogenic L389S mutation (SETX L389S), and using genome editing, we generated an isogenic corrected iPSC line (SETX WT) and an isogenic knock-out line lacking SETX expression (SETX KO).