PROS1 and hereditary antithrombin deficiency: Patients with rVTE, despite therapeutic doses of anticoagulant therapy, shouldbe assessed for several factors, such as treatment compliance, heparin-inducedthrombocytopenia (HIT), antiphospholipid syndrome, thrombophilia (protein C,protein S, Factor V Leiden mutation, and antithrombin deficiency), malignancycompression or invasion resulting in tumor-thrombosis [29].