Factor V Leiden thrombophilia is an inherited blood clotting disorder, according to the National Human Genome Research Institute. The cause is a genetic mutation that increases the risk of abnormal blood clots forming in blood vessels.
People who have factor V Leiden thrombophilia have a greater than average risk of having a blood clot in the large veins of the legs, which is known as deep vein thrombosis. They also have a higher than average risk of pulmonary embolism, which occurs when a blood clot lodges in the lungs. Having a pulmonary embolism or DVT below the age of 50 is a key symptom of factor V Leiden thrombophilia, according to the National Human Genome Research Institute. Other symptoms include recurring pulmonary embolisms or DVT.
If a doctor suspects that a patient has factor V Leiden thrombophilia, he can use a coagulation screening test or genetic testing to diagnose the condition. People with the condition can have one or two copies of the genetic mutation that causes it, according to the National Human Genome Research Institute. People with one copy of the mutation have a risk of clotting that is four to eight times higher than normal, while people with two copies are up to 80 times more likely to develop a blood clot.