(A) Pedigree of the affected family. The proband was diagnosed with HCM and a MYBPC3 truncation mutation (p.R943x) was identified by genetic screening. (B) Sanger sequencing of patient corrected (943cor), patient (943het), and patient homozygous (943hom) iPSCs. (C) Micropatterned iPSC-CMs stained with Troponin (green) and DAPI (top row), and MYBPC3 (green), alpha sarcomeric actin (αSA; red), and DAPI (bottom row; scale bar 10 µm). (D) Representative plots of fluorescence intensity longitudinally throughout myofibers analyzed using plot profile (ImageJ), showing MYBPC3 expression in micro-patterned iPSC-CMs (943cor, 943het) and αSA (943hom). (E) Quantification of sarcomeric length based on αSA stained micro-patterned iPSC-CMs (n=10, 11, and 4 cells, respectively). (F) Distribution of the obtained sarcomere length measurements in 943cor (blue), 943het (red), and 943hom (dark). (G) Cell size measurement of unpatterned iPSC-CMs (n=4–6 differentiation batches with 20–130 cells each, respectively). HCM - hypertrophic cardiomyopathy; SCD - sudden cardiac death; CHF - congestive heart failure; ICD - implantable cardioverter defibrillator; AU - arbitrary units.