Factor V Leiden Analysis
Factor V Leiden (F5) R506Q mutation is the most common cause of inherited thrombophilia and accounts for over 90 percent of activated protein C (APC) resistance. Individuals heterozygous for this mutation have an increased risk for venous thrombosis (approximately five- to tenfold). Individuals homozygous for this mutation have an even higher risk for venous thrombosis (approximately fifty- to one hundredfold). Specific acquired or environmental factors may dramatically increase this baseline risk.
Analysis for the factor V Leiden R506Q mutation is offered as a specific DNA test, or as part of the thrombosis panel which also includes the Prothrombin (Factor II) G20210A mutation analysis. Individuals with multiple thrombophilic mutations develop venous thromboembolism at a younger age and are at higher risk for recurrent thrombosis than those with a single defect.
A factor V gene haplotype, HR2 may confer mild APC resistance and interact with the factor V Leiden mutation to produce a more severe APC resistance phenotype. Reflex testing to factor V HR2 analysis is available upon request with any abnormal factor V Leiden result.
Indications for Testing
- Deep vein thrombosis
- Pulmonary embolism
- Superficial venous thrombosis, phlebitis or thrombophlebitis
- Personal history of two or more blood-clotting incidents
- Family history of blood clots or factor V Leiden
- Unexplained fetal loss after 10 weeks gestation
- Unexplained severe preeclampsia, placental abruption, or a fetus with intrauterine growth retardation
3 – 4 mL whole blood in purple top EDTA tube
Blood samples stored overnight should be refrigerated or kept cold. Blood samples should never be frozen. Specimens being sent from outside facilities should be packaged with a cold pack according to standard medical safety practices. The specimen should be shipped by overnight priority [scheduled to arrive by Friday morning at the latest].
Center for Human Genetics Laboratory
10524 Euclid Avenue, Sixth Floor
Cleveland, OH 44106
For local samples, please call Client Service (216-844-5227) to arrange for sample pick-up.
3 – 9 days
- Factor V Leiden Analysis – 81241
- Factor V HR2 Analysis – 81400
Please submit a completed Molecular Requisition for each sample.