(A) CRaTER-flox gene-editing approach. Red asterisk indicates variant. (B) Representative genotyping gel using primers indicated in A. Parental: WTC11 MYH7^WT/WT. Edited: WTC11 MYH7^WT/R403W. (C) Representative sequencing chromatograms. (D) CRaTER-flox editing efficiency to generate variant hiPSC lines. (E) Representative hiPSC-CM force curves as measured with traction force microscopy. (F) Log-transformed maximum hiPSC-CM active traction force z scores normalized to benign lines and raw force values. Blue: benign/likely benign (B); red: pathogenic/likely pathogenic (P) variant. Box bounds: upper and lower quartiles; midline: median; whiskers: 1.5 × IQR. Circles: variant-associated cardiomyopathy reported in ClinVar or de Frutos et al. (4). (G–I) Mean maximum MYH7 exon 12–14 hiPSC-CM active traction forces (G), maximum traction velocity (H), and maximum relaxation velocity (I). Kruskal-Wallis test, P < 0.05; post hoc 2-tailed Mann-Whitney U test with Bonferroni’s correction, *P < 0.0167. Error bars in G–I indicate SEM.