Diagnostic Test Directory

Molecular Genetics Laboratory

CHOP in the News

Clinical Lab Products quotes Avni Santani, PhD, Scientific Director, Molecular Genetics Laboratory, in a story about next-gen sequencing. Read the story »

Laboratory Update

Testing for the Noonan spectrum of disorders is now available at the Molecular Genetics Laboratory. Learn more about Noonan spectrum testing »

Factor II Prothrombin (Prothrombin G20210A Gene Mutation)

  • Synonyms: Coagulation Factor II, Hyperprothrombinemia
  • LIS Mnemonic: MBFACII


    Collect whole blood in a purple top (EDTA) tube (preferred). Extracted DNA is also acceptable.

    Volume Required

    5 ml whole blood or 1 ug extracted DNA

    Minimum Required

    3 ml whole blood


    Refrigerate sample until shipment. Send the sample at room temperature with overnight delivery for receipt Monday through Friday within 24 hours of collection.


    Whole blood can be refrigerated until shipment.

    Unacceptable conditions

    Heparinized specimens, severely hemolyzed specimens, frozen, clotted or possibly commingled specimens, blood in non-sterile or leaky containers, mislabeled or inappropriately labeled specimens.

    Specimen Handling

    Do not heat, freeze or centrifuge blood before shipment. Refrigerate sample until shipment.

Days Performed

Mon - Fri 9:00am to 4:00pm


Within 10 days



Disease Information

Clinical Features:

Coagulation factor II is proteolytically cleaved to form thrombin in the first step of the coagulation cascade which ultimately results in clot formation. Factor II also plays a role in maintaining vascular integrity during development and postnatal life. Mutations in factor II lead to various forms of thrombosis and dysprothrobinemia. Factors that predispose to thrombosis in G20210A heterozygotes include: the number of prothrombin G20210A alleles; presence of coexisting genetic abnormalities, such as factor V Leiden; and acquired thrombophilic disorders, such as hyperhomocysteinemia (plasma concentrations of homocysteine >12 µmol/L). Circumstantial risk factors for thrombosis include pregnancy and oral contraceptive use.

Molecular Genetics:

The factor II gene is located on chromosome 11p11-q12. The mutation is a single nucleotide polymorphism at nucleotide 20210 (G>A). The prothrombin g.20210G>A mutation is the second most commonly identified inherited thrombophilia risk factor after factor V Leiden. The prothrombin mutation is rare in the Asian and African American population and is found more frequently in individuals of southern European descent. The clinical expression of prothrombin thromophilia is variable; many individuals heterozygous or homozygous for the g.20210G>A allele never develop thrombosis, and while most G20210A heterozygotes who develop thrombotic complications remain asymptomatic until adulthood, some have recurrent thromboembolism before age 30 years. Presence or absence of the factor II (prothrombin) mutation does not rule out mutations in other genes involved in APC resistance (ie, factor V Leiden).

Test Methods:

We detect the g.20210G>A single nucleotide polymorphism using sequence analysis.

Detection Rate:

The detection rate for sequencing is 100% of factor II genotypes at nucleotide 20210.

Related Tests:

We offer the following tests related to Inherited Thrombophilia: Factor V Leiden (c.1691G>A; p.Arg506Glu)


Test results with interpretation will be mailed and/or faxed to the referring physician or send out lab following completion of the test. Additional reports will be provided as requested.


The clinical utility of the assay is to identify a genetic risk factor for patients who have had a hyper coagulation episode, quantify risk, and to determine the need to avoid other environmental risk factors.

Search Lab Test Directory

Search by disease or test name

View a full list of all lab tests

Contact Us

Ask for more information about our laboratory services.