First, to evaluate the scope of the analysis, we assessed the number of genes expressed to a detectable level in both the Braineac and GTEx data sets. We found that of 515 genes within 1 Mb of a significant PD risk variant, 470 were expressed to a detectable level and passed quality control in both data sets. Second, we applied Coloc and TWAS to test whether the regulation of the expression of these overlapping genes was associated with PD risk. When applying the Coloc method to these 470 genes, 9 in Braineac and 27 in GTEx showed strong evidence for colocalization (PPH4 ≥ 0.75) in at least 1 brain region. In the TWAS analysis, 61 genes were found to be significantly associated with PD risk at an FDR level of 0.05. Five genes (WDR6 [OMIM 606031], CD38 [OMIM 107270], GPNMB [OMIM 604368], RAB29 [OMIM 603949], and TMEM163 [OMIM 618978]; Table 1) replicated across the Coloc and TWAS results (eFigure 1A in Supplement 1). Example regional association plots for the genes with the highest PPH4 in Braineac (RAB29) and GTEx (CD38
