Pro-thrombin and Factor V Leiden

The annual incidence of venous thromboembolism (deep vein thrombosis and pulmonary embolism) is approximately 117 per 100,000 persons or about 1 per 1,000 person-years. ACMG selected two mutations associated with increased risk for occurrence/recurrence of venous thrombosis—the factor V Leiden and the prothrombin 20210G>A (factor II) 1

Prothrombin and Factor V Leiden are genetic mutations associated with an increased risk of blood clot formation. Prothrombin refers to a protein involved in the blood clotting process, while Factor V Leiden refers to a specific mutation in the Factor V gene, which affects the activity of a clotting protein called Factor V.

Individuals with these mutations have an altered blood clotting mechanism, making them more susceptible to developing abnormal blood clots, a condition known as thrombophilia. This increased clotting tendency can lead to various health issues, including deep vein thrombosis (DVT), pulmonary embolism (PE), and other clot-related complications. Prothrombin and Factor V Leiden mutations can be associated with an increased risk of miscarriages and may be considered as part of the evaluation for recurrent pregnancy loss.

When should you get tested?

Test specifications

Technique Variant types TAT Sample requirements
Sanger sequencing Mutation 3 - 4 weeks 2 ml EDTA Blood / 2 ug DNA


  1. Spector, Elaine B., et al. "Technical standards and guidelines: venous thromboembolism (Factor V Leiden and prothrombin 20210G> A testing): a disease-specific supplement to the standards and guidelines for clinical genetics laboratories." Genetics in Medicine 7.6 (2005): 444-453.