Factor V Leiden Mutation

Sample type: Whole Blood

Other names: c.1601G>A (p. Arg534Gln) variant

By Healthmatters Editorial Team

Peer-reviewed sources

Normal / Not detected

A "Normal / Not detected" result for the Factor V Leiden mutation means that the specific genetic change linked to an increased risk of developing venous thromboembolism, a type of blood clot that starts in a vein, was not found in the tested individual's DNA. This result suggests that the person's risk of venous thromboembolism due to Factor V Leiden is not elevated because of this specific genetic factor. However, it's important to remember that venous thromboembolism can still occur due to other genetic, lifestyle, or environmental factors.

Abnormal / Detected

An "Abnormal / Detected" result for the Factor V Leiden mutation means that the individual tested has a specific genetic variation in their F5 gene, which can increase their risk of developing venous thromboembolism, a condition where blood clots form in the veins, potentially blocking blood flow and leading to complications like deep vein thrombosis (DVT) or pulmonary embolism (PE). This mutation makes the blood more prone to clotting, a condition known as hypercoagulability. Diagnosing this mutation involves genetic testing, which can be recommended if there's a personal or family history of blood clots, especially in individuals under 50, or in cases with unexplained clots. The Factor V Leiden mutation can be inherited from one or both parents; having one copy (heterozygous) increases clotting risk mildly, whereas two copies (homozygous) lead to a much higher risk. Symptoms of venous thromboembolism can include swelling, pain, and redness in the affected limb, sudden shortness of breath, chest pain, and in severe cases, can be life-threatening. Treatment options focus on preventing clot formation and may include anticoagulant medications (blood thinners), lifestyle changes to improve circulation and reduce clot risk (like regular exercise, not smoking, and managing weight), and, in some situations, the use of compression stockings or filters placed in the veins to prevent clots from traveling to the lungs. The management of Factor V Leiden mutation emphasizes preventing thrombotic events, given the absence of a direct cure for the genetic mutation itself.

Venous thromboembolism is a complex condition that can be caused by a combination of genetic factors, lifestyle choices, and specific situations. One key genetic risk factor is the presence of a specific change in the F5 gene, known as Factor V Leiden (c.1601G>A or p. Arg534Gln variant). People who carry one copy of this variant are 6 to 8 times more likely to develop venous thromboembolism, while those with two copies (one from each parent) face an approximately 80 times higher risk. The risk increases even further for individuals who carry both the Factor V Leiden variant and another variant called c.*97G>A in the F2 gene, making them about 20 times more susceptible. Certain combinations of genetic factors, including both mentioned variants, could further elevate this risk.

Other risk factors that can contribute to the development of venous thromboembolism include low levels of certain proteins (protein C, protein S, or antithrombin III), being older, male, having a personal or family history of blood clots, smoking, undergoing surgery, being immobile for long periods, having cancer, or receiving treatments like tamoxifen, raloxifene, oral contraceptives, hormone replacement therapy, and being pregnant.

To manage the risk of blood clots, it's essential to follow established medical guidelines tailored to each person's situation. Genetic counseling can also provide valuable information on the implications of test results and advise on testing for family members.

The Factor V Leiden variant mentioned is the main focus of testing, which has a diagnostic accuracy greater than 99%. However, it's important to interpret these results in the context of the individual's overall health and other risk factors.

While molecular-based tests are very reliable, they are not perfect and can sometimes give false results due to various factors like other genetic variations, blood transfusions, bone marrow transplants, sample mix-ups, or inaccuracies in family history documentation.

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Written by Healthmatters Editorial Team

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