Alternative Names
Blood clotting diseases; blood clotting disorders; hereditary thrombophilia; thrombotic events; thrombosis
Symptoms & Characteristics
Thrombophilia is the tendency to form abnormal blood clots in blood vessels. This can be due to an excess production of clotting factors or a deficiency of anti-clotting proteins. Thrombophilia can be inherited or acquired. Although most people with an inherited thrombophilia never develop abnormal blood clots, they are at increased risk over the general population for:
- clots in veins - called venous thrombosis, especially deep vein thrombosis (DVT) in arms and legs;
- clots in lungs - called pulmonary embolism (PE);
- stroke or transient ischemic attacks (TIAs);
- pregnancy loss and complications such as placental abruption (in women)
Common inherited thrombophilias include:
Some of the less common inherited thrombophilias include:
Elevated homocysteine levels have also been associated with increased blood clotting risk. People with two copies of a specific MTHFR gene variant called 677T have an increased risk for elevated homocysteine levels. High homocysteine levels have also been associated with some vitamin deficiencies (i.e. vitamin B6), kidney failure and other causes. Although debated by some, recent studies have suggested that having MTHFR by itself, is not considered an inherited thrombophilia. About 12% of Caucasians of Northern European descent have two copies of the 677T variant.
Treatment
The management of thrombophilia depends on the clinical situation.
If someone notices or experiences any of the signs or symptoms common to thrombophilia, it is important to see a doctor.
For women with thrombophilia, it is always important to speak with a doctor regarding appropriate care and management before and during pregnancy.
How Common Is It?
About 20% of people in the United States have an inherited thrombophilia.
About 25% to 30% of people with a previous DVT or PE have an inherited thrombophilia.
Genetics & Inheritance
The different inherited thrombophilias are caused by mutations in different genes. The mode of inheritance also varies by condition.
Other factors also increase the risk of blood clots in people with an inherited thrombophilia. These factors can include increasing age, obesity, trauma, surgery, smoking, the use of oral contraceptives (birth control pills) or hormone replacement therapy, and pregnancy. The combination of the different gene mutations involved in blood clotting may also influence risk.
Genetic Testing
Clinical genetic testing for the Thrombophilia Panel is available online (over the internet). Go to the Tests tab to link to the best providers, compare providers and read provider reviews.
- The Thrombophilia Panel typically includes testing for Factor V Leiden and prothrombin thrombophilia. Some providers test for a third condition, MTHFR, as well. Many health professionals currently believe that a fasting homocysteine level is more informative and clinically useful than MTHFR gene testing when assessing thrombophilia risk.
Clinical genetic testing for these common thrombophilias as well as less common thrombophilias is available through an in person genetic consultation for people who are considered at risk. Use our find a genetic professional directory to locate a trained genetic professional in your area.
Informational genetic testing for susceptibility to thrombosis is available online (over the internet). This testing is available individually or as part of a whole genome scan. Whole genome scanning involves analyzing thousands of SNPs at once related to a number of different health conditions.
- At this point, many genetic professionals do not consider this testing clinically useful or medically relevant, but for informational purposes only. Go to the Tests tab to link to the best providers, compare providers and read provider reviews.
Support & More Information
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