APP and Alzheimer disease: In addition, by using an AD iPSC line carrying APP duplication (“APP cells” hereafter), we used paired Cas9nVQR for the one-step generation of isogenic iPSC lines with monoallelic, biallelic, or triallelic knockout of the target gene; among them was an isogenically corrected line (“Iso cells” hereafter) that had undergone monoallelic APP disruption (i.e., carrying two functional APP alleles) as an APP wild-type revertant.