The plasma levels of pS129-α-synuclein were significantly higher in PD patients (12.9 ± 8.7 fg/mL, minimal value: 0.1 fg/mL, maximal value: 67.4 fg/mL) than controls (0.8 ± 0.7 fg/mL, minimal value: 0.03 fg/mL, maximal value: 8.7 fg/mL; p < 0.001, Table 2, Figure 1A). This evidence concerns the gene SNCA and Parkinson disease.