Inherited thrombophilic states

Thrombophilic states are a group of conditions associated with increased pr edisposition to thromboembolic events. The well-recognized inherited thromb ophilic states include resistance to activated protein C (APC) (Factor V Le iden) and deficiencies of plasma antithrombin, protein C, and protein S, Th ese entities are aberrations in the natural anticoagulant systems that exis t in plasma and at the endothelial cell level. Other causes of inherited th rombophilia include hyperhomocysteinemia, abnormalities in the proteins of the fibrinolytic system, dysfibrinogenemias, deficiency of heparin cofactor II, abnormal thrombomodulin, and the recently described variation in the p rothrombin gene. Most of the inherited abnormalities recognized to date are associated with venous thromboembolism (VTE) rather than arterial thrombos is. Approximately half of VTE episodes in patients with inherited thromboph ilias occur in relation to events that are generally recognized as predispo sing states, such as surgery, pregnancy, and immobilization, In this review , the risks of VTE associated with inherited risk factors are discussed, an d guidelines for the diagnosis and management are presented.