MTHFR and Venous thrombosis: In addition, we found that factor-V-Leiden is a risk factor that is independent of other known determinants of thrombosis; specifically, it is independent of the G20210A prothrombin or MTHFR-gene-mutation, whereas MTHFR-mutation in combination with hyperhomocysteinemia is independently from factor-V-Leiden-mutation also a risk factor for DVT in AIVC.