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Your doctor may test you for Factor V Leiden if you tend to develop abnormal blood clots. Testing includes special screening and confirmatory blood tests to detect the presence of the mutation, FVL.
You can get tested for factor V Leiden (FVL) after discussing your concerns with your doctor. The tests include special screening and confirmatory blood tests to detect the presence of the mutation, FVL.
A genetic or activated protein C (APC) resistance test or a coagulation screen (screening test) is the initial test that helps the doctor diagnose FVL. Though it is possible to get yourself tested from an advertised genetic test purchased directly, it is not recommended. Always consult your doctor or a medical professional (geneticist) who works in the field of genetics beforehand.
The definitive test (confirmatory test) for FVL is called targeted mutation analysis (a type of DNA test) of the F5 gene for the Leiden mutation.
If you tend to develop clots or abnormal blood clots in your legs or lungs, your doctor may ask you to undergo testing for factor V Leiden, as well as prothrombin 20210 (PT 20210 or Factor II mutation). Both are genetic mutations that increase the risk of excessive clotting. You will need to undergo two separate blood tests that will look at your deoxyribonucleic acid (DNA) for the mutations.
What is factor V Leiden (FVL)?
Factor V Leiden (FVL) or factor “5” Leiden is a genetic mutation (change) that increases the affected person’s risk of developing abnormal (excessive) clotting.
Blood clotting is a protective mechanism that prevents excessive bleeding. Factor V is one of the proteins that help your blood to clot when there is external or internal bleeding in your body. However, when the gene that is involved in the making of factor V undergoes mutation, called factor V Leiden, you may develop clots in the deep veins of your leg (deep vein thrombosis, DVT) or the clots may travel from the legs to the lungs (pulmonary embolism), which is a life-threatening condition.
Not everyone who has FVL suffers from DVT or a pulmonary embolism. In fact, many people may not face any problem from the mutation.
What percentage of the population has factor V Leiden?
In the United States, Factor V Leiden (FVL) exists in approximately five percent of the population. People with Northern European ancestry are more likely to have the mutation than Native Americans and African Americans.
In some countries of Northern Europe, FVL is present in up to 10 to 15 percent of the population. It is less common in regions, such as South America, Africa and Asia.
What are the signs and symptoms of factor V Leiden?
Factor V Leiden itself does not cause any signs or symptoms. It only increases your tendency to form excessive blood clots in any veins of your body. Most of the clots disappear on their own while some others turn life-threatening.
A clot in the deep vein of your leg or deep vein thrombosis (DVT) may not cause any symptoms. If signs and symptoms do occur, they can include:
- Pain
- Swelling
- Redness
- Warmth
However, if a clot travels to your lungs (pulmonary embolism), it is a medical emergency, with signs and symptoms that include:
- Sudden shortness of breath
- Sudden chest pain
- Hemoptysis (coughing up blood)
- Rapid or irregular heartbeat
- Cyanosis (bluish discoloration of the skin)
- Dizziness