Molecular testing for coagulation abnormalities
Molecular testing is frequently used in conjunction with other laboratory analyses in the evaluation of patients with hemorrhagic as well as thrombotic disorders. The most common thrombophilic defects, factor V Leiden and the prothrombin G20210A mutation, are detected by molecular testing. Functional assays are used for the less common inherited hypercoagulable states, such as antithrombin or protein C deficiency, since no single mutation has been found to predominate in these deficiency states. Functional assays are also used to identify patients with hemophilia, but genetic analysis of these individuals is frequently performed to aid in the diagnosis of carriers and identify potentially affected children. Patients with thrombotic events are treated with anticoagulant therapy, which has traditionally been warfarin, a vitamin K antagonist. Recently, polymorphisms in CYP 2C9 and VKOR1 have been shown to affect the dose of warfarin required to achieve a target international normalized ratio (INR). Similarly, polymorphisms associated with the metabolism of clopidogrel have also been identified. Prospective clinical trials will be necessary to determine the optimal use of this information.
