We found that the parental history of PD (OR = 3.58; 95%CI: 1.58, 8.94), exposure to metals (OR = 2.34; 95%CI: 1.31, 4.27), polymorphism rs356219 in the SNCA gene (OR = 2.10, 95%CI: 1.30, 3.43 for CC vs. TT), exposure to agricultural chemicals (OR = 1.98; 95%CI: 1.28, 3.10), and older age (OR = 1.03; 95%CI: 1.01, 1.05, per year increase) were associated with an increased risk of developing PD. This evidence concerns the gene SNCA and Parkinson disease.