Factor V Leiden Thrombophilia
Most common inherited thrombophilia caused by an activated protein C resistance mutation in factor V.
This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.
This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Hematoloji department. Book Appointment →
What is Factor V Leiden Thrombophilia?
Factor V Leiden (FVL) is the most common inherited thrombophilia in populations of European descent (carrier frequency 3-8% in heterozygotes). It is a single-base substitution (1691 G>A) in the F5 gene replacing arginine with glutamine at position 506 (R506Q), one of the cleavage sites where activated protein C (APC) inactivates factor Va. The mutated factor Va is degraded more slowly, resulting in prolonged thrombin generation and a hypercoagulable state called APC resistance.
Heterozygous FVL increases venous thromboembolism (VTE) risk approximately 3-7 fold, while homozygous FVL increases risk 20-80 fold. The lifetime VTE risk in heterozygotes without other factors remains modest (5-10%), so most carriers never have an event. Risk multiplies with concurrent factors: estrogen-containing oral contraceptives, hormone replacement therapy, pregnancy, postpartum, surgery, immobilization, and other thrombophilias.
Diagnosis is by APC resistance screening (modified clotting assay) followed by genetic testing for F5 R506Q if abnormal. Most carriers do not require prophylactic anticoagulation; thromboprophylaxis is targeted to high-risk situations (major surgery, pregnancy in selected cases, prolonged immobilization). After a first VTE, decisions about extended anticoagulation depend on whether the event was provoked, additional risk factors, and personal/family history rather than carrier status alone.
Symptoms
Risk Factors
When to See a Doctor?
If you experience any of the following symptoms, seek medical attention promptly:
- Personal history of VTE for thrombophilia evaluation
- Family history of VTE in young relatives
- Recurrent unexplained miscarriage
- Pre-pregnancy counseling with known FVL
- Considering oral contraceptives or HRT with FVL or family history
- Major surgery planned in known carrier
- Unusual-site thrombosis
- Cerebral or mesenteric venous thrombosis
Treatment Methods
Which Department to Visit?
You can visit our Hematoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.
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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.