Together, our results indicated that the expression levels of 14 hub genes (SLC18A2, SLC6A3, KCNJ6, FOXA2, NR4A2, CACNA1E, DRD2, RET, EN1, FGF13, SYNGR3, RIMBP2, KCNB1, and RAB3C) were decreased in SN tissues of PD samples. The gene discussed is RET; the disease is Parkinson disease.