Thrombophilia, polymorphisms, and vascular disease.

Thrombophilia traditionally refers to rare inherited defects leading to enhanced coagulation, especially of the venous system. In recent years, a broader search for genetic polymorphisms of prothrombotic genes has been carried out to determine the relative impact on venous and arterial thrombosis. The bulk of evidence is drawn from numerous, often small, heterogeneous, case control association studies, with a variety of end points (deep venous thrombosis, myocardial infarction, or stroke). The data are often conflicting and inconclusive with only factor V Leiden and prothrombin polymorphisms having clear associations with venous thrombosis. Many of the polymorphisms interact with established cardiovascular risk factors, in particular smoking, to increase greatly the risk of a thrombotic episode. Future studies will need to consider the confounding factors of sample size, race, and clinical end points as well gene-environment interactions.