HNRNPA1 and amyotrophic lateral sclerosis: To understand the effect of loss-of-function of two FTD/ALS-associated RBPs on the neuritic proteome, we used CRISPRi (16) to knock down TDP-43 and hnRNPA1 by lentiviral sgRNA transduction of iPSCs prior to proceeding with neuron differentiation (Figure 5A).