Generation of gene-edited hiPSC-CMs. (A) Sequence alignment of troponin T splice isoforms expressed in humans reveals that all isoforms contain the R92 residue. (B) CRISPR-Cas9 targeting of R92Q in troponin T. The R92Q mutation was added via homology-directed repair. The gRNA sequence for targeting was 5′-CCT​TCT​CCA​TGC​GCT​TCC​GGN​GG-3′. From our screen, 21% of the cells were homozygous for the R92Q mutation (CGG→CAA). (C) Karyotyping of R92Q gene-edited cells reveals a normal karyotype.