TTN and familial dilated cardiomyopathy: After lentiviral infection, ~85% of both control and DCM iPSC-derived cardiomyocytes were GFP positive (GFP+) (Supplementary Fig S5C), and a virtually complete, specific skipping of TTN exon 326 was achieved in both groups exclusively with U7snRNA-TTNAONs-IRES-GFP, as detected by RT–PCR and sequencing (Fig2B and Supplementary Fig S6A).