ALDH1A1 and Parkinson disease: ALDH1A1 (PD vs. control: 0.063 ± 0.022 vs. 0.053 ± 0.016, p = 0.047), apoptotic protease activating factor 1 (APAF1, PD vs. control: 0.459 ± 0.188 vs. 0.354 ± 0.082, p = 0.006), CR1 (PD vs. control: 0.073 ± 0.031 μM vs. 0.054 ± 0.032, p = 0.026), and colony stimulating factor 1 receptor (CSF1R, PD vs. control: 0.375 ± 0.082 μM vs. 0.325 ± 0.094, p = 0.032) were significantly upregulated in PBMCs of PD patients (Table 2).