The expression levels of the 12 hub genes (SLC18A2, SLC6A3, KCNJ6, NR4A2, DRD2, RET, EN1, FGF13, SYNGR3, RIMBP2, KCNB1, and RAB3C) in SN tissues of PD samples were significantly decreased compared with those of normal samples (P value <0.01 and log FC ≤ −1.0). This evidence concerns the gene SLC18A2 and Parkinson disease.