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Genetic and Rare Diseases Information Center (GARD)

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Factor V Leiden thrombophilia


* Not a rare disease
Other Names for this Disease
  • APC resistance, Leiden type
  • Hereditary resistance to activated protein C
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What are the signs and symptoms of factor V Leiden thrombophilia?

Individuals affected by factor V Leiden thrombophilia have an increased risk of developing blood clots. The severity of factor V Leiden thrombophilia is extremely variable. Many individuals with the factor V Leiden allele never develop a blood clot. Although most individuals with factor V thrombophilia do not experience their first thrombotic event until adulthood, some have recurrent thromboembolism before age 30 years. The chance a person will develop a blood clot is affected by the number of factor V Leiden mutations, the presence of coexisting genetic abnormalities, and non-genetic risk factors.  Non-genetic risk factors include surgery, long periods of not moving (like sitting on a long airplane ride), birth control pills and other female hormones, childbirth within the last 6 months, and traumas or fractures.[1][2]

Individuals who inherit one copy of the factor V Leiden mutation have a fourfold to eightfold increase in the chance of developing a clot.  Homozygotes (people who inherit two factor V Leiden mutations) may have up to 80 times the usual risk of developing a blood clot. Considering that the risk of developing an abnormal blood clot averages about 1 in 1,000 per year in the general population, the presence of one copy of the factor V Leiden mutation increases that risk to 4 to 8 in 1,000, and having two copies of the mutation may raise the risk as high as 80 in 1,000.[1][3]

People with factor V Leiden have an increased chance of having a blood clot that forms in large veins in the legs (deep venous thrombosis, or DVT) or a clot that travels through the bloodstream and lodges in the lungs (pulmonary embolism, or PE).[1] Symptoms of deep vein thrombosis usually include leg pain, tenderness, swelling, increased warmth or redness in one leg. The symptoms of pulmonary embolism usually include cough, chest pain, shortness of breath or rapid heartbeat or breathing.[4] To learn more about the symptoms of DVT and PE, click here.
Last updated: 6/29/2012

  1. Factor V Leiden thrombophilia. Genetics Home Reference. August 2010; Accessed 8/8/2011.
  2. Kujovich J.. Factor V Leiden thrombophilia. GeneReviews. March 2010; Accessed 8/8/2011.
  3. Ahmed R, Gupta P, Kannan M, Choudhry V, Saxena R. Thrombosis Research. 2003; Accessed 2/13/2008.
  4. Deep venous thrombosis. MedlinePlus. 2007; Accessed 2/13/2008.