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Can Fam Physician. 2010 April; 56(4): 353.
PMCID: PMC2860828


Factor V Leiden

Factor V Leiden is the most common inherited risk factor associated with thrombophilia. Risk of venous thromboembolism (VTE) is moderated by complex gene-gene and gene-environment interactions.

Bottom line. Genetic testing for factor V Leiden can identify those at increased risk of VTE and allow for individual risk assessment and risk avoidance. Testing is recommended for those with VTE at younger than 50 years of age; recurrent VTE; venous thrombosis at an unusual site; VTE while pregnant or while taking oral contraceptives; a first incidence of VTE, with strong family history of VTE; and for asymptomatic relatives of individuals with a factor V Leiden mutation considering oral contraceptive use or pregnancy; and others. General population screening is not recommended, given the low absolute thrombotic risk in heterozygotes.

The complete Gene Messenger—Factor V Leiden by the GenetiKit research team is available on CFPlus.* Past Gene Messenger articles can be accessed online at On the home page, click on Collections in the left-hand menu, then click on Genetics.


Funding was provided by the Canadian Institutes of Health Research.


Competing interests

None declared

The GenetiKit research team, a group of family physicians, genetic counselors and geneticists, designed the Gene Messenger series to provide practical information to help family physicians and their patients make informed choices about rapidly emerging genetic discoveries. The series is a collection of up-to-date, definitive, short reviews on genetics topics that have made headlines, and offers recommendations regarding referral for genetic services or testing.

*The Gene Messenger on factor V Leiden is available at Go to the full text of this article online, then click on CFPlus in the menu at the top right-hand side of the page.

Articles from Canadian Family Physician are provided here courtesy of College of Family Physicians of Canada