DAergic neurons derived from induced pluripotent stem cells (iPSCs) from a PD patient carrying triplication of the SNCA demonstrate high expression levels of markers of oxidative stress and augmented susceptibility to H2O2, suggesting that the overdose of α-synuclein intrinsically changes the balance of ROS production and antioxidant activities in DAergic neurons [81]. This evidence concerns the gene SNCA and Parkinson disease.