DMD and Becker muscular dystrophy: Subsequently, we generated two hiPSC lines, the DMD Δ3–7 hiPSC line as a model for DMD and the DMD Δ3–9 hiPSC line as a model for the mild form of BMD,23,31 from the WT hiPSCs with dual indicators through electroporation of Cas9 and two single guide RNAs (sgRNAs) targeting sequences in introns 2 and 7 for Δ3–7 and introns 2 and 9 for Δ3–9 (Figure 1D; Table S2).15