In animal models of PD via MPTP injections, it is possible to reproduce the progressive degradation of the nigrostriatal dopaminergic system, degradation of other monoaminergic systems of the brain, and peripheral nervous system, motor and non-motor symptoms, etc. The only significant drawback of MPTP models in rodents, but not in monkeys, is an absence of α-synuclein overproduction and aggregation [33,34,35]. The gene discussed is SNCA; the disease is Parkinson disease.