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Reviewed August 2008
What is prothrombin thrombophilia?
Prothrombin thrombophilia is an inherited disorder of blood clotting. Thrombophilia is an increased tendency to form abnormal blood clots in blood vessels. People who have prothrombin thrombophilia are at somewhat higher than average risk for a type of clot called a deep venous thrombosis, which typically occurs in the deep veins of the legs. Affected people also have an increased risk of developing a pulmonary embolism, which is a clot that travels through the bloodstream and lodges in the lungs. Most people with prothrombin thrombophilia never develop abnormal blood clots, however.
Some research suggests that prothrombin thrombophilia is associated with a somewhat increased risk of pregnancy loss (miscarriage) and may also increase the risk of other complications during pregnancy. These complications may include pregnancy-induced high blood pressure (preeclampsia), slow fetal growth, and early separation of the placenta from the uterine wall (placental abruption). It is important to note, however, that most women with prothrombin thrombophilia have normal pregnancies.
How common is prothrombin thrombophilia?
Prothrombin thrombophilia is the second most common inherited form of thrombophilia after factor V Leiden thrombophilia. Approximately 1 in 50 people in the Caucasian population in the United States and Europe has prothrombin thrombophilia. This condition is less common in other ethnic groups, occurring in less than one percent of African-American, Native American, or Asian populations.
What genes are related to prothrombin thrombophilia?
Prothrombin thrombophilia is caused by a particular mutation in the F2 gene. The F2 gene plays a critical role in the formation of blood clots in response to injury. The protein produced from the F2 gene, prothrombin (also called coagulation factor II), is the precursor to a protein called thrombin that initiates a series of chemical reactions in order to form a blood clot. The particular mutation that causes prothrombin thrombophilia results in an overactive F2 gene that causes too much prothrombin to be produced. An abundance of prothrombin leads to more thrombin, which promotes the formation of blood clots.
Other factors also increase the risk of blood clots in people with prothrombin thrombophilia. These factors include increasing age, obesity, trauma, surgery, smoking, the use of oral contraceptives (birth control pills) or hormone replacement therapy, and pregnancy. The combination of prothrombin thrombophilia and mutations in other genes involved in blood clotting can also influence risk.
Read more about the F2 gene.
How do people inherit prothrombin thrombophilia?
The risk of developing an abnormal clot in a blood vessel depends on whether a person inherits one or two copies of the F2 gene mutation that causes prothrombin thrombophilia. In the general population, the risk of developing an abnormal blood clot is about 1 in 1,000 people per year. Inheriting one copy of the F2 gene mutation increases that risk to 2 to 3 in 1,000. People who inherit two copies of the mutation, one from each parent, may have a risk as high as 20 in 1,000.
Where can I find information about diagnosis or management of prothrombin thrombophilia?
These resources address the diagnosis or management of prothrombin thrombophilia and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about prothrombin thrombophilia?
You may find the following resources about prothrombin thrombophilia helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for prothrombin thrombophilia?
What if I still have specific questions about prothrombin thrombophilia?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding prothrombin thrombophilia?
blood clotting ; clotting ; coagulation ; embolism ; gene ; hormone ; hormone replacement therapy ; injury ; mutation ; placenta ; population ; protein ; pulmonary ; pulmonary embolism ; surgery ; thrombin ; thrombophilia ; thrombosis ; trauma ; veins
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (4 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.