In plasma, levels of OCN [PD vs. HC, 11,716.4pg/ml (8,052.7–14,679.4) vs. 4833.1 pg/ml (1,953.1–8,847.8), P < 0.001] and OPN [PD vs. HC, 16,733.7 pg/ml (12,446.0–19,981.3)vs 12,333.7 pg/ml (6,341.4–16,882.7), P < 0.001] were increased in the PD patients relative to the controls. The gene discussed is SPP1; the disease is Parkinson disease.