PRKN and Parkinson disease: Mitophagy has been implicated in many physiological processes, such as tumorigenesis, neurological and immunological disorders.42, 43 It has been demonstrated that mitochondrial dysfunction is accompanied by a large amount of ROS production, mitochondrial division/fusion changes, and there is impaired mitophagy in the early stage of Alzheimer's disease.44 Mice with Parkin and PINK1 genetic deletion had symptoms similar to Parkinson's disease, with progressive mitochondrial damage.45 Thus, Parkin and PINK1 play key roles in the process of clearing damaged mitochondria.