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Factor V Leiden Thrombophilia

What is Factor V?

Factor V LeidenFactor V (factor five) is a protein and an important component of the coagulation system. It is also known as proaccelerin or labile factor and functions as a cofactor that activates an enzyme called thrombin. Thrombin in turn cleaves fibrinogen to form fibrin, which functions to cross link and form the dense meshwork that makes up the majority of a blood clot when activated. Deficiency of Factor V leads to increased bleeding whereas its abnormality may lead to increased risk of forming blood clots (thrombosis)

What is factor V Leiden and why is it important?

The gene for Factor V is located on the first chromosome, and Factor V Leiden refers to a mutation in that gene resulting in production of abnormal Factor V and a condition is called Factor V Leiden thrombophilia. The affected individuals are at an increased risk for forming blood clots such as deep venous thrombosis (DVT). The clots can then travel into the lungs causing a potentially life threateninig condition called pulmonary embolism. Due to increased propensity of the blood to form clots, the risk of a heart attack may also be slightly increased.

Factor V Leiden has been also implicated in pregnancy complications further increasing the risk of blood clots and pulmonary embolism that exist during pregnancy. Furthermore pregnant women with certain sub-types of Factor V Leiden mutation have a small increased risk of preeclampsia (high blood pressure during pregnancy), low birth weight babies, as well as miscarriage and stillbirth due to either clotting in the placenta or umbilical cord.

Who should be tested?

  • Individuals¬†who have had an unexplained blood clot (thrombotic episode), especially under the age of 50
  • Individuals¬†who have recurrent DVT/VTE (venous thrombo embolism) episodes
  • Individuals¬†who have a strong family history of thrombosis
  • Women considering pregnancy

I am positive for Factor V Leiden. What should I do?

Although factor V Leiden mutation can lead to serious complications, only about 10 percent of individuals with the factor V Leiden mutation ever develop abnormal clots. Likewise most women with factor V Leiden thrombophilia have normal pregnancies. Your doctor can run additional tests to check your blood clotting system and evaluate your history and other risk factors. If necessary, medications can lessen your risk of developing additional blood clots and help you avoid potentially serious complications.

Where can I learn more about Factor V Leiden?