In CSF, patients with PD had significantly lower levels of OCN [14,817.5 pg/ml (8,145.9–18,998.3) vs. 18,264 pg/ml (12,835.5–22,342.3), P = 0.002; Figure 1A] and OPG [204.3 pg/ml (107.3–307) vs. 282.7 pg/ml (215.3–444.1), P = 0.008; Figure 1C] relative to HC. Here, TNFRSF11B is linked to Parkinson disease.