Did you know that Factor V Leiden is a type of inherited thrombophilia present in approximately 2% of the population?
What is factor V Leiden and how is it related to thrombophilias?
The thrombophilia is a condition in which the blood has an increased tendency to form clots, even when there is no obvious injury. These clots, when they form in places where they should not, can cause serious problems such as a deep vein thrombosis in the legs or a pulmonary embolism if the clot travels to the lungs.
One of the most common causes of hereditary thrombophilia is the factor V Leiden a genetic variant of the gene F5 which produces a key protein in the coagulation process: the factor V.
Why is factor V Leiden associated with an increased risk of thrombus?
Under normal conditions, the factor V is involved in clot formation when a blood vessel is injured. Once the clot has fulfilled its function, another protein in the body, called the activated protein C acts as a brake to stop coagulation by deactivating factor V.
But in people with factor V Leiden, this protein has a mutation that causes it to be resistant to the action of activated Protein C. As a result, coagulation continues longer than necessary, and that increases the risk of abnormal blood clot formation.
What does it imply at the genetic level and how useful is it to be tested?
The V Leiden factor is due to a point mutation in the gene F5, which encodes the factor V protein. This mutation is hereditary: it is transmitted from parents to children.
Each person has two copies of this gene, one from each parent. You can inherit:
- A mutated copy and a normal (heterozygous form), which represents a moderate risk.
- Two mutated copies (homozygous form), which implies a significantly higher risk.
Taking a genetic test like the one offered by ADNTRO can help you determine whether you carry this mutation and in what form. This information can be useful for:
- Assess your personal risk of thrombosis.
- In case of having higher risk, make more informed decisions (such as surgery or pregnancy).
- Plan with your doctor the use of hormonal contraceptives or hormonal therapies.
What factors can increase the risk?
Having Factor V Leiden does not mean that you will develop clots but it does increases the risk especially if combined with other factors. Some examples:
- Obesity
- Prolonged immobility (long trips, hospitalization)
- Recent surgery or trauma
- Estrogen use (oral contraceptives or hormone therapy)
- Smoking
- Additional hereditary thrombophilias
- Pregnancy
How common is the V Leiden factor?
Factor V Leiden is uncommon in the population:
- The variant is present in 1 to 4% of individuals.
- It is less common in East Asians, Africans and Native Americans.
- The homozygous form is present in less than 1% of the population.
