Hemophilia (see Hemophilia) is the most common hereditary clotting disorder. Hemophilia involves an inherited deficiency of certain clotting factors (proteins that help the blood clot, stopping bleeding). In hemophilia A, clotting factor VIII is deficient and in hemophilia B, factor IX is deficient. However, rarely people have an inherited deficiency of another clotting factor. Examples include a deficiency of factor V, VII, X, or XI. Most of these disorders are inherited in an autosomal recessive fashion. In other words, the person needs to receive two copies of the abnormal gene, one from each parent.
In general, deficiency of factor XI is uncommon. However, it is more common in certain ethnic groups. About half of cases of factor XI deficiency occur among people of Eastern European Jewish ancestry. Factor XI deficiency affects both males and females and may cause bleeding after injury or surgery. Spontaneous bleeding episodes are usually less frequent and milder than in hemophilia A or B.
Bleeding that is difficult to control after injury or surgery may indicate that a person has an uncommon clotting disorder. Doctors measure the levels of clotting factors in a blood sample in people who experience bruising or bleeding that is difficult to control.
Treatment depends on the specific factor that is deficient but usually includes replacing the deficient clotting factor.
Last full review/revision April 2014 by Joel L. Moake, MD