Skip to Main Content

Factor II

Thrombophilia is an inherited or acquired susceptibility to thrombosis due to an abnormality of blood coagulation. Factor II-related thrombophilia (also known as prothrombin-related thrombophilia) is the second most common form of thrombophilia after factor V Leiden. While many individuals with factor II-related thrombophilia do not develop blood clots, there is a 2-5 fold increased risk for thrombosis over that of the general population. Thrombotic risks associated with factor II-related thrombophilia can include deep-vein thrombosis, pulmonary embolism, myocardial infarction, and cerebral-vein thrombosis.

F2 is the only gene known to be associated with factor-II related thrombophilia, and encodes the protein prothrombin. Individuals with factor II-related thrombophilia are heterozygous or homozygous for a specific mutation, 20210G>A, in the F2 gene. Heterozygosity occurs in 1.7-3% of 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 V Leiden and MTHFR, are also available at the Genetics Center Molecular Diagnostic Laboratory.

Reasons for Referral

  • An individual with unprovoked venous thromboembolism (VTE) before the age of 50.
  • An individual with recurrent VTE.
  • An individual with VTE at an unusual site (cerebral, mesenteric, portal, or hepatic veins).
  • A woman with VTE during pregnancy.
  • A woman with VTE associated with the use of estrogen-containing oral contraceptives or hormone replacement therapy.
  • An individual with a first VTE at any, with a first-degree relative with VTE before age 50.

Testing Methods

DNA is isolated and analyzed specifically for the factor II (prothrombin) mutation (G20210A).

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


CPT Codes

CPT’s: 81240, G0452

Request to Schedule Telecounseling Make a Payment