The AUCs for plasma, CSF, and the combined assessment of OPN when comparing PD patients with control groups were 0.73 (95% CI = 0.632–0.814), 0.589 (95% CI = 0.486–0.687), and 0.739 (95% CI = 0.641–0.822), respectively (Figure 1F). This evidence concerns the gene SPP1 and Parkinson disease.