PSMC4 and Parkinson disease: Logistic regression analyses establish a strong association between PD and reduced expression of PSMC4, SKP1, and HSPA8 (OR = 0.640, 95% CI = 0.415–0.987; OR = 0.000, 95% CI = 0.000–0.075; OR = 0.550, 95% CI = 0.368–0.823, respectively).