MMRN1 and cardiac hypertrophy: We confirmed that a large proportion of up‐regulated DEG genes intersecting between our data and previous scRNA studies on both human DCM patients and mouse cardiac hypertrophy models were ECM genes and the ECM pathway was commonly activated in the HCM cardiomyocytes of published HCM scRNA‐seq or snRNA‐seq datasets (Figures S8 and S9).5, 6, 7, 8, 9, 11