To highlight the possible implications of developmental anomalies and substrate changes for cardiomyopathy studies with hiPSC-CMs, we compared cardiomyocytes from a Duchenne Muscular Dystrophy (DMD) patient carrying a deletion of exon 50 in the DMD gene (Guan et al., 2014) with control cell lines and with an isogenic control created by CRISPR-Cas9 targeting the DMD gene (c.263delG) (Pioner et al., 2019b). The gene discussed is DMD; the disease is Duchenne muscular dystrophy.