Abnormal ETC function is closely linked to the pathogenesis of various diseases: in Alzheimer’s disease (AD), for example, ETC impairment induces neuronal apoptosis through ROS-mediated neuroinflammation (immune response) and cytochrome c-dependent apoptotic signaling (neuronal apoptotic signaling) [13,14]. The gene discussed is CYCS; the disease is Alzheimer disease.