To gain insight into the pathogenic interplay between SGs and ALS, we monitored SG assembly and disassembly in two patient‐derived iPSC lines carrying distinct C9orf72‐HRE mutations (C9‐1: ~6000–8000 bp repeat expansion; C9‐2: ~2400 bp repeat expansion). Here, C9orf72 is linked to amyotrophic lateral sclerosis.