Factor V Leiden
Test Code
Factor V Leiden (FV)
CPT Codes
83891-3A x1; 83892-3A x2; 83900-3A x1; 83914-3A x1; 83909-3A x1; 83912-3A x1; 83912-25 x1
Specimen
Whole blood or buccal swabs
Volume
5 mL of whole blood or four buccal swabs
Minimum Volume
3 mL of whole blood or four buccal swabs
Container
Lavender-stopper (EDTA) tube or paper envelope for dried buccal swabs
Storage Instructions
Maintain at room temperature or refrigerate
Cause for Rejection
Hemolyzed specimen; quantity not sufficient
Use
The Factor V Leiden polymorphism is the result of a single point mutation (1691 G>A) that results in substitution of a glutamine for arginine at amino acid 506. The amino acid change prohibits the inactivation of Factor V by activated protein C, thereby creating a state of activated protein C resistance (APCR) and increasing the risk of thrombosis. Individuals with this polymorphism have a 10-20 fold increased thrombotic risk.
.Limitations
Other genetic variants of the Factor V gene that are not detected in the assay may influence Factor V activity. Other genetic and non-genetic factors may also influence the balance of proper coagulation.
Methodology
Multiplex polymerase chain reaction and allele specific primer extension (Tag-It [TM]).
Turnaround Time
Five business days after receipt of specimen. STAT turnaround time of 3 business days is available for an additional charge.
References
Ho WK et al. Risk of recurrent venous thromboembolism in patients with common thrombophilia. Arch Intern Med 2006;166:729-736.
Tripodi A. Issues concerning the laboratory investigation of inherited thrombophilia. Mol Diag 2005;9(4):181-186.
Bauer KA. Role of thrombophilia in deciding on the duration of anticoagulation. Semin Thromb Hem 2004;30(6):633-637.
Kim RJ and Becker RC. Association between factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations and events of the arterial circulatory system: a meta-analysis of published studies. Am Heart J 2003;146:948-957.