To further explore the effects of FUS on snRNP biogenesis in a physiological cellular model, we then used CRISPR/Cas9 to target the endogenous FUS locus and generate isogenic hiPSC lines harbouring the ALS-associated P525L mutation as well as complete knockout of the FUS gene using the CRISPR-Trap approach31 (Fig. 5a). Here, FUS is linked to amyotrophic lateral sclerosis.