Coagulation
Hereditary thrombophilia / hypercoagulopathies
Prothrombin gene mutation (G20210A) / hyperprothrombinemia
Author: Jeremy C. Parsons, M.D.
Last author update: 1 June 2012
Last staff update: 23 September 2020
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Prothrombin gene mutation (G20210A) / hyperprothrombinemia
Cite this page: Parsons JC. Prothrombin gene mutation (G20210A) / hyperprothrombinemia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/coagulationprothrombingenemutation.html. Accessed November 27th, 2024.
Definition / general
- Mutation in G to A transition at nucleotide 20210 in 3 untranslated portion of prothrombin gene, which introduces a new Hind III site
- Associated with (may not directly cause) increased prothrombin levels, 2 - 5x increased risk of venous thrombosis
- Patients with G20210A mutation have increased levels of TAFI (Thrombin Activated Fibrinolysis I, a protein that inhibits clot lysis), which makes clots exist longer, leading to increased thrombotic episodes
- Risk is multiplicative if taking oral contraceptives and have factor V Leiden gene
- Heterozygous form occurs in 1 - 2% of normal individuals, 6 - 20% of patients with venous thrombosis
- Testing via nucleic acid based assay is preferred, as the lack of linearity of the clot - based Factor II assay at the high end makes this unsuitable for diagnostic use
Laboratory
- Recommended patients to test:
- Patients with recurrent venous thromboembolic events
- First episode before age 50
- First unprovoked venous thromboemboli at any age
- Thromboses at unusual anatomic sites (cerebral, mesenteric, portal or hepatic veins)
- Venous thromboemboli in patient with first degree relative with venous thromboemboli before age 50 years
- Venous thromboemboli related to pregnancy or estrogen use, or unexplained pregnancy loss in second or third trimesters
- Young individuals with myocardial infarction and no other risk factors
- Also test factor V Leiden and other mutations (combination most clearly impacts clinical decision making)
- Testing not recommended:
- As general population screen
- Routine test during pregnancy
- Routine test before or during oral contraceptive use or hormone replacement therapy
- As newborn initial test
- As initial test in patients with arterial thrombotic events
Treatment
- Patients with thromboemboli and this mutation should receive similar treatment as other patients with venous thromboemboli
Additional references
