Factor XI deficiency
Introduction
Factor XI (pronounced factor 11) deficiency, or haemophilia C, is an inherited bleeding disorder.
Blood travels around the body through a network of blood vessels. Bleeding occurs when a blood vessel is damaged or injured. In an unaffected person, blood flows out of the vessel and blood platelets stick together to form a plug. A blood clot forms and acts like glue to repair the blood vessel and stop the bleeding. The clotting process, or coagulation, turns blood from a liquid to a solid state.
Factor XI is a blood protein that is needed for the blood clotting process. It also helps to activate factor IX (factor 9) which is another blood clotting protein. In factor XI deficiency, the level of factor XI in the blood is lower than that of an unaffected person. Because of the deficiency, blood takes longer to clot, and the person has a tendency to bleed for longer than usual.
Factor XI deficiency affects an estimated 1 in 100,000 people, however it occurs more frequently among the Ashkenazi Jewish population, affecting an estimated 1 in 190. The condition affects males and females in equal numbers.
People with factor XI deficiency must not take aspirin in any form because it makes bleeding worse. Always read the label of any medicine package carefully and do not use the drug if it contains aspirin. If in doubt, ask a pharmacist.
Some medicines, such as warfarin, affect blood clotting and are therefore not suitable for people with factor read more
