CCN2 and Parkinson disease: Taken together, this study identified hub genes for multiple brain regions including the substantia nigra (SLC6A3, SLC18A2, and TH), putamen (BMP4 and SNAP25), prefrontal cortex area (SNAP25), and cingulate gyrus (CTGF, CDH1, and COL5A1) in PD based on WGCNA.