[Congenital thrombophilia].

Congenital thrombophilia is a thrombotic diathesis caused by a variety of genetic abnormalities in blood coagulation factors or their inhibitory factors associated with physiological thrombus formation. Patients with congenital thrombophilia often present with unusual clinical episodes of venous thrombosis (occasionally combined with pulmonary embolism, known as venous thromboembolism) at a young age and recurrence in atypical vessels, such as the mesenteric vein and superior sagittal sinus, often with a family history of this condition. Studies in Japan as well as in western countries have shown congenital thrombophilia to be caused by a wide variety of genetic abnormalities in natural anticoagulant proteins, such as antithrombin, protein C, and protein S. However, there may still be many unknown causes of hereditary thrombosis. We recently reported a case of hereditary thrombosis induced by a novel mechanism of antithrombin resistance, that is, congenital thrombophilia caused by a gain-of-function mutation in the gene encoding the coagulation factor prothrombin.