An inherited blood-clotting disorder due to a change in the blood's factor V protein.
Factor V Leiden (FAK-tur five LIDE-n) increases the chance of having clumps of blood, known as clots. This can be life-threatening. Women with the disorder risk developing blood clots during pregnancy or when taking the hormone estrogen.
Most people never develop symptoms. The first indication of the disorder may be a blood clot. Some clots do no damage and disappear on their own. Others can be life-threatening depending on what part of the body is affected.
Treatment may include blood-thinning medicines. Other precautions, including keeping the legs moving and wearing compression stockings, can reduce the risk of having blood clots.