Harvard Health Publishing Q&A: Factor V Leiden

 Factor V Leiden (FVL) is a genetic mutation that affects blood clotting. It is one of the most common inherited thrombophilias, a group of diseases that increase the risk of abnormal blood clotting. To shed light on this condition, we present a question and answer session with Harvard Health Publishing featuring Drs. Elizabeth Johnson, renowned expert in hematology.

Question 1: What is factor V Leiden and how does it affect blood clotting?

Dr. Johnson: Factor V Leiden is a mutation of one of the clotting factors in the blood, specifically factor V. Under normal circumstances, factor V plays a key role in regulating blood clotting. However, in individuals with this mutation, factor V Leiden is resistant to a natural anticoagulant called protein C. This resistance makes the blood more prone to clotting, potentially leading to abnormal and dangerous blood clots.

Question 2: How common is factor V Leiden and who is at risk?

Dr. Johnson: Factor V Leiden is one of the most common genetic mutations associated with an increased risk of blood clotting, especially in people of European descent. Approximately 5% of Caucasians in the United States carry at least one copy of this mutation. Having one copy increases the risk of clotting, but having two copies (homozygous) significantly increases the risk.

Q3: Are there any symptoms or warning signs of Factor V Leiden?

Dr. Johnson: Factor V Leiden often causes no noticeable symptoms until a blood clot forms. When a clot develops, it can cause symptoms such as swelling, pain, warmth and redness in the affected area, typically in the legs (deep vein thrombosis) or lungs (pulmonary embolism). However, many individuals with this mutation may never experience a clot.

Q4: How is factor V Leiden diagnosed?

Dr. Johnson: Factor V Leiden can be diagnosed with a blood test that detects the presence of the mutation. This test is often done if a person has a personal or family history of blood clots or if unexplained blood clotting events occur.

Question 5: What are the treatment options for Factor V Leiden?

Dr. Johnson: Factor V Leiden treatment aims to reduce the risk of blood clots. For individuals with one copy of the mutation, preventive measures may include lifestyle changes such as staying active, maintaining a healthy weight, and avoiding smoking. In cases of recurrent blood clots, doctors may prescribe blood thinners (anticoagulants) such as warfarin or newer oral anticoagulants.

Q6: Can factor V Leiden be prevented?

Dr. Johnson: Because factor V Leiden is a genetic mutation, it cannot be prevented. However, the associated risks of clotting can be managed with lifestyle modifications and medications under the guidance of a health care provider.

Question 7: Is factor V Leiden a significant problem during pregnancy?

Dr. Johnson: Yes, it can be. Pregnancy itself increases the risk of blood clots, and the presence of factor V Leiden further increases this risk. Pregnant women with the mutation may require special monitoring and, in some cases, blood thinners to reduce the risk of complications such as deep vein thrombosis or placental blood clots.

Factor V Leiden is a genetic mutation that affects blood clotting and can increase the risk of abnormal clot formation. Although this is a common condition, it does not always lead to symptoms or complications. Early detection with blood tests and appropriate treatment, including lifestyle changes and medications, can help individuals with Factor V Leiden lead healthy lives while minimizing the risk of dangerous blood clots. If you suspect you may have this mutation or have a family history of clotting disorders, it is important to consult a healthcare professional for proper evaluation and management.