Prothrombin 20210A : F2 Targeted Analysis

Test Information

F2 targeted analysis is a molecular test used to identify the common 20210G>A variant in the gene associated with Prothrombin.

Turnaround Time

1 week

CPT Code(s)





  • F2

Clinical Information

Two mutations within genes in the blood coagulation pathway that have been implicated as significant factors for thrombotic risk. These two defects, factor V Leiden and prothrombin 20210A, are responsible for over 60% of all cases of inherited thrombophilia. In addition to being significant risk factors for hypercoagulation, the mutations are frequently found in, but are not limited to, people of European descent. Carriers of the Leiden R506Q mutation have an 8 fold increased risk for venous thrombosis and homozygotes have a 91 fold increased risk. Specific acquired or environmental factors may dramatically increase this baseline risk. Approximately 5% percent of the Caucasian population carries the Factor V Leiden mutation. Three percent of the Caucasian population carries the prothrombin mutation. The molecular diagnosis of these mutations is done with the polymerase chain reaction and restriction endonuclease digestion or allele specific oligonucleotide amplification.


Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis.

Specimen Requirements

The preferred sample type is peripheral blood collected in an EDTA (purple top) tube - at least 2-3ml for pediatric patients and 5-6ml for adult patients. Extracted DNA, dried blood spots, and saliva are also accepted for this test. Saliva samples must be submitted in an approved saliva kit. Contact the lab to receive a saliva kit or to have one sent to your patient.

Transport Instructions

The specimen should be kept at room temperature and delivered via overnight shipping. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.

Prenatal Testing Information

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.

Have Questions? Need Support?

Call our laboratory at 1-800-473-9411 or contact one of our Laboratory Genetic Counselors for assistance.
Robin Fletcher, MS, CGC
Falecia Thomas, MS, CGC

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