PARK7 and Parkinson disease: Recent studies have demonstrated that the oxidation of DA produces oxidative products, leading to mitochondrial dysfunction, impaired protein degradation, α-synuclein aggregation into neurotoxic oligomers, and oxidative stress in vitro, and the DA content is critical for both DJ-1 knockout and A53T α-synuclein transgenic mice to develop PD pathological features, providing evidence for DA action in PD pathogenesis in vivo [19].