DCM mouse model, different sources of cardiomyocytes, adeno‐associated virus 9 (AAV9), gene knockout, RNAscope miRNA in situ hybridization, mRFP‐GFP‐LC3B reporter, echocardiography and transmission electron microscopy were adopted for mechanistic explorations. The gene discussed is MAP1LC3B; the disease is familial dilated cardiomyopathy.