Thromboembolism in patients with hereditary deficiency of coagulation factors.

Despite significantly prolonged prothrombin time endogenously caused by factor VII deficiency, a 65-year-old woman suffered a fatal pulmonary embolism. This seemingly paradoxic phenomenon prompted our review of 14 other patients with various coagulation factor deficiencies who also had thromboembolic events. It is postulated that certain factor deficiencies may protect against venous and/or arterial thrombosis. A large-scale prospective study of this population may help define the relative importance of the various coagulation factors, platelets, and the vessel wall in thrombosis and atherogenesis and allow a rational evaluation of anticoagulant therapy.