What is a prothrombin gene mutation?
A prothrombin gene mutation is an inherited genetic change that increases the risk of developing abnormal blood clots. The mutation affects the factor II (F2) gene, which helps the body make prothrombin, a protein involved in normal clotting. As a result, the body produces more prothrombin than normal, increasing the likelihood of clot formation.
Also known as the prothrombin G20210A mutation or factor II mutation, this blood clotting disorder is one of the most common inherited conditions linked to excessive clotting. Whether you’ve recently been diagnosed, have a family history of the condition, or have experienced a blood clot, Penn Medicine specialists provide expert evaluation, treatment, and long-term support every step of the way. Through our specialized blood clotting disorders program, people have access to expert care, including genetic testing to help guide diagnosis and treatment decisions.
Recognizing factor II mutation symptoms
Most people with a prothrombin gene mutation don’t experience symptoms unless a blood clot develops. Blood clots can be serious and may require emergency care. It’s associated with an increased risk of deep vein thrombosis (DVT) and pulmonary embolism. However, many people with the mutation never experience a blood clot at all. Get medical help right away if you have symptoms of DVT or pulmonary embolism.
Symptoms depend on where the clot forms and may include:
- Swelling, pain, warmth, or redness in an arm or leg (signs of DVT)
- Sudden shortness of breath, chest pain, rapid heartbeat, or coughing up blood (signs of pulmonary embolism)
- Recurrent blood clots, especially at a younger age or without a clear cause
- Blood clots during pregnancy or after childbirth
Types of prothrombin gene mutation
There are two types of prothrombin gene mutations: heterozygous and homozygous. The most common type, heterozygous, occurs when you inherit one copy of the mutated gene from one parent. Homozygous occurs when you inherit a mutated gene from both parents. This form is less common and carries a higher risk of blood clots.
What causes a mutation in the factor II gene?
A prothrombin genetic mutation is inherited from one or both parents. It involves a change in the F2 gene, which leads to a higher production of prothrombin than usual, making blood more likely to clot.
Having the mutation doesn’t always lead to a blood clot, but any of the following can increase your risk:
- Surgery or a serious injury
- Long periods of sitting or bed rest
- Pregnancy and childbirth
- Estrogen-containing birth control or hormone therapy
- Smoking
- Obesity
- Other inherited clotting disorders
Diagnosing a prothrombin gene mutation
To diagnose a prothrombin gene mutation, your doctor will ask about your symptoms, health history, family history, and risk factors for blood clots. Blood tests can check how well your blood clots and look for other clotting disorders. One test, called a prothrombin time test, measures how long it takes blood to clot. However, this test can’t diagnose a prothrombin gene mutation because many people with the condition have a normal prothrombin time. Genetic testing can confirm a prothrombin G20210A mutation and show whether you inherited one or two copies of the changed gene.
If a blood clot is suspected, imaging tests may be used to locate it. Testing may be recommended if you have had an unexplained or recurrent blood clot, a strong family history of clotting disorders, or certain pregnancy complications.
Can the prothrombin gene mutation be treated?
Treatment doesn’t correct the mutation itself. Instead, it focuses on preventing and treating blood clots. Your doctor may recommend blood-thinning medications to help prevent new blood clots and stop existing clots from getting larger. You might take them regularly or for a short time when your risk is higher, like before or after surgery or during pregnancy. Your care team may also recommend making lifestyle changes to lower your risk, including staying active, avoiding long periods of inactivity, maintaining a healthy weight, and not smoking. Some people may benefit from ongoing monitoring so that blood clots can be treated right away.
Specialized care for inherited blood clotting disorders
Living with a prothrombin gene mutation can raise questions about blood clot prevention, surgery, pregnancy, and long-term health. Working with specialists who treat inherited clotting disorders can help you understand your risks and treatment options.
At Penn Medicine, hematologists work closely with experts in vascular medicine, genetics, maternal-fetal medicine, and other specialties to provide coordinated care.
Our team offers:
- Accurate diagnosis: Comprehensive testing to confirm a prothrombin gene mutation and identify other inherited or acquired clotting disorders.
- Risk assessment: Recommendations based on your medical history, family history, and other factors that affect your risk of blood clots.
- Advanced treatment options: Access to the latest blood-thinning medications and evidence-based strategies to help prevent blood clots.
- Pregnancy expertise: Close collaboration with maternal-fetal medicine specialists to support people with inherited clotting disorders before, during, and after pregnancy.
- Coordinated care: Specialists across multiple disciplines work together to provide expert care and long-term follow-up when needed.
No matter where you are on your journey, we’re here to help you manage your clotting risk and protect your long-term health.