The genetic susceptibility genes in patients are mainly concentrated in the dopamine metabolic system genes, including the catecholamine oxymethyltransferase gene, the monoamine oxidase gene, the dopamine receptor gene, and the dopamine transporter (DAT) gene (gene symbol: SLC6A3), in which the DAT gene plays an essential role in the pathogenesis of PD. Here, SLC6A3 is linked to Parkinson disease.