iPSC-derived SNs with P525L FUS-eGFP showed a 5-fold decrease in tracing (p < 0.05, 2way ANOVA, Sidak post-test for multiple comparisons; Supplementary Figures S2C,D), consistent with the age-dependent neurodegeneration observed in ALS. The gene discussed is FUS; the disease is amyotrophic lateral sclerosis.