Prothrombin G20210A Molecular Mutation Assay

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Subject: Prothrombin G20210A Molecular Mutation Assay

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Definition

  • The prothrombin mutation c.20210G>A (20210G>A) in the F2 gene is associated with increased plasma prothrombin levels and an increased risk of venous thrombosis (OMIM# 32790). Heterozygosity for the prothrombin c.20210G>A mutation is associated with an approximately threefold increased risk of venous thrombosis. Homozygosity for this mutation is rare, but the associated risk of venous thrombosis is likely to be higher than the heterozygous risk. Other factors can further increase the risk of thrombosis.

  • Normal values: negative or no mutations are found.

Use

  • Prothrombin c.20210G>A testing should be performed in the following cases:

    • A first venous thrombotic embolism (VTE) before age 50 years

    • A first unprovoked VTE at any age

    • A history of recurrent VTE

    • Venous thrombosis at unusual sites such as the cerebral, mesenteric, portal, or hepatic veins

    • VTE during pregnancy or the puerperium

    • VTE associated with the use of oral contraceptives or hormone replacement therapy

    • A first VTE at any age in an individual with a first-degree family member with a VTE before age 50 years

    • Women with unexplained fetal loss after 10 weeks of gestation

  • Prothrombin c.20210G>A testing may be considered in the following cases:

    • Women with unexplained early-onset severe preeclampsia, placental abruption, or significant intrauterine growth retardation

    • A first VTE related to tamoxifen or other selective estrogen receptor modulators (SERM)

    • Female smokers younger than 50 years with a myocardial infarction

    • Individuals older than age 50 years with a first provoked VTE in the absence of malignancy or an intravascular device

    • Asymptomatic adult family members of probands with one or two known c.20210G>A mutation in the F2 gene, especially those with a strong family history of VTE at a young age

    • Asymptomatic female family members of probands with known prothrombin thrombophilia who are pregnant or who are considering oral contraception or pregnancy

    • Women with recurrent unexplained first-trimester loss with or without second- or third-trimester loss

    • Children with arterial thrombosis

Limitations

  • The results of a genetic test may be affected by DNA rearrangements, blood transfusion, bone marrow transplantation, or rare sequence variations.

  • Genetic causes of thrombosis, other than the prothrombin c.20210G>A mutation, will not be detected.

 
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