The mechanisms of aspirin and its reduction in venous thromboembolism is not entirely understood, but believed to occur via differing mechanisms, including inhibition of cyclooxygenase-1 (which reduces thromboxane A2, a promoter of platelet aggregation), prevention of thrombin formation and thrombin-mediated coagulant reactions, acetylation of proteins involved in coagulation (such as fibrinogen), and enhancing fibrinolysis [23,26]. The gene discussed is PTGS1; the disease is venous thromboembolism.