GFRA2 and Parkinson disease: Other PD related genes that we found to be differentially expressed between PD_R vs. PD/HC_NR included SEPT5 (down compared to CD4 PD_NR and HC_NR), GFRA2 (up compared to CD8 PD_NR and HC_NR), MAOA (down compared to CD8 HC_NR), AQP9 (up compared to CD4_NR), LAMP3 (up compared to CD4 PD_NR and HC_NR), PLK1 (down compared to HC_NR), and MPO (down compared to CD4 PD_NR).