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Factor V Leiden

Thrombophilia is an inherited or acquired susceptibility to thrombosis due to an abnormality of blood coagulation. Factor V Leiden thrombophilia is the most common form of inherited thrombophilia and is characterized by poor anticoagulant response to activated protein C,thus imparting an increased risk to develop venous thrombosis. Individuals with factor V Leiden have a 3-8 fold increased risk for deep venous thrombosis compared to the general population. Thrombotic risks associated with factor V Leiden thrombophilia can include deep-vein thrombosis, with the leg being the most common site along with increased risk for pulmonary embolism. Also, factor V Leiden thrombophilia has been associated with an increased risk for pregnancy loss, and possibly other pregnancy complications such as preeclampsia, fetal growth retardation, and placental abruption.

The F5 gene encodes the protein factor V, and a specific disease-causing mutation in this gene is associated with factor V Leiden thrombophilia. Individuals with factor V Leiden thrombophilia may be either heterozygous or homozygous for a specific mutation, 1691G>A (R506Q), in the F5 gene. Heterozygosity occurs in 3-8% of the Caucasian population in the United States and Europe, and is less common in other ethnic groups. Molecular testing of additional genes associated with thrombotic risk, including factor II and MTHFR, is also available at the Genetics Center Molecular Diagnostic Laboratory.

Reasons for Referral

  • Neonates or children with non-catheter related idiopathic VTE or stroke of uncertain etiology.
  • An individual with unprovoked venous thromboembolism (VTE) at any age (especially prior to the age of 50).
  • An individual with recurrent VTE.
  • An individual with VTE at an unusual site (cerebral, mesenteric, portal, or hepatic veins).
  • An individual with a VTE and a first-degree relative also with VTE prior to the age of 50.
  • A female with VTE during pregnancy.
  • A female with VTE associated with the use of oral contraceptives or hormone replacement therapy.
  • A female smoker with a myocardial infarction or stroke before the age of 50 years.
  • Asymptomatic adult individuals with a family history of VTE at a young age or a known diagnosis of Factor V Leiden.

Testing Methods

PCR and RFLP analysis for the specific R506Q mutation.

Turn Around Time

6 days or fewer

Specimen Requirements and Shipping/Handling

Blood: A single tube with 1-5 mL whole blood in EDTA (lavender top).


Store blood at 4°C until shipment. Ship at ambient temperature in an insulated container via overnight delivery within 96 hours of collection.

Send Specimen(s) to:

Genetics Center
211. S Main Street
Suite AA
Orange, CA 92868
Tel: (714)288-3500


Test Limitations

Targeted mutation analysis for the c.1691G>A (p.R506Q) mutation. Test results on DNA extracted from a patient with recent liver transplantation or hematopoietic stem cell transplantation must be interpreted with caution. Molecular genetic identity testing of donor tissue may be required in these scenarios.

CPT Codes

CPT’s: 81241, G0452

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