Billia et al. observed mitochondrial swelling and abnormal mitochondrial function in PINK1-deficient mice, which eventually brings about left ventricular dysfunction as well as pathological cardiac hypertrophy.218 Song et al. found that in adult mice, ablating Drp1 interrupts mitochondrial fission and significantly elevates Parkin levels, enhancing Parkin-mediated mitophagy.219 Excessive activation of mitophagy causes mitochondrial depletion and fatal cardiomyopathy. The gene discussed is PRKN; the disease is cardiac hypertrophy.