library_construction_protocol: Next-generation amplicon sequencing was carried out on the MiniSeq Sequencing System (Illumina©). In brief, a 250bp GATA4_HDR site PCR product was amplified, from gDNA, with GATA4 pAMPF1 (5'ACACTCTTTCCCTACACGACGCTCTTCCGATCTcaccttttacttggacatgaagc3') and GATA4 pAMPR1 (5'GTGACTGGAGTTCAGACGTGTGCTCTTCCGATCTgtacaaaggaagaagacaaggga3') (21) for 150bp, paired end, >10,000 reads (MiniSeq, Illumina, Australia) and reads aligned to the HDR or WT amplicon with CRISPResso2 software (22) RNA libraries were prepared with the SureSelect Strand-Specific XT HS2 Poly-A kit and sequenced at Genomics WA (Perth, Australia) on an Illumina NovaSeq 6000 platform (paired-end, 100bp. ~30 million reads per sample).