Furthermore, the findings of the Medco-Mayo Warfarin Effectiveness study (MM-WES) demonstrated that preemptive genotyping of the CYP2C9 and VKORC1 genes resulted in a 43% reduction in the risk of hospitalization due to bleeding or thromboembolism, with an overall 31% decrease in hospitalizations compared to those in the control group [43]. This evidence concerns the gene VKORC1 and Thromboembolism.