Factor V Leiden

This inherited disorder increases the risk for deep vein thrombosis (clots that appear deep in the body, usually in the thigh or lower leg) and complications with pregnancy, such as miscarriage. It is the most common inherited clotting disorder and occurs most often in children of European descent, affecting about 5 percent of whites. Although many people inherit this abnormality, only about 10 percent will ever have an abnormal blood clot.