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Factor XI Deficiency

National Organization for Rare Disorders, Inc.


It is possible that the main title of the report Factor XI Deficiency is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • haemophilia C
  • hemophilia C
  • plasma thromboplastin antecedent deficiency
  • PTA deficiency
  • Rosenthal syndrome

Disorder Subdivisions

  • None

General Discussion


Factor XI deficiency is a rare genetic bleeding disorder caused by reduced levels and insufficient activity of a blood protein called factor XI. Factor XI is a clotting factor. Clotting factors are specialized proteins that are essential for proper clotting, the process by which blood solidifies like glue to plug the site of a wound to stop bleeding. Individuals with factor XI deficiency do not bleed faster or more profusely than healthy individuals, but, because their blood clots poorly, they may have difficulty stopping the flow of blood from a deep or surgical wound. This may be referred to as prolonged bleeding or a prolonged bleeding episode. The severity of factor XI deficiency can vary from one person to another. In many cases, prolonged bleeding episodes only occur after surgery, dental procedures or trauma. Bleeding tendencies in factor XI deficiency are unpredictable and inconsistent, making the disorder difficult to manage in some cases. Factor XI deficiency is caused by disruptions or changes (mutations) to the F11 gene. Factor XI deficiency is inherited autosomally and can occur in people of either sex.


Factor XI deficiency was first described in the medical literature in 1953. It used to be also referred to as hemophilia C in order to distinguish it from the better known hemophilia types A and B. In rare cases, factor XI deficiency can be acquired during life (acquired factor XI deficiency). This report deals with the genetic form. Although the genetic form is present at birth, as it is a mild bleeding disorder symptoms do not usually occur until later in life.


National Hemophilia Foundation

116 West 32nd Street, 11th Floor

New York, NY 10001


Tel: (212)328-3700

Fax: (212)328-3777

Tel: (800)424-2634



Canadian Hemophilia Society

400-1255 University Street


Quebec, H3B 3B6


Tel: 5148480503

Fax: 5148489661

Tel: 8006682686



NIH/National Heart, Lung and Blood Institute

P.O. Box 30105

Bethesda, MD 20892-0105

Tel: (301)592-8573

Fax: (301)251-1223



World Federation of Hemophilia

1425 René Lévesque Blvd. W. Suite 1010


Quebec, H3G 1T7


Tel: 5148757944

Fax: 5148758916



Hemophilia Federation of America

210 7th St. SE

Suite 200B

Washington, DC 20003


Tel: (202)675-6984

Fax: (202)675-6983

Tel: (800)230-9797



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223


Madisons Foundation

PO Box 241956

Los Angeles, CA 90024

Tel: (310)264-0826

Fax: (310)264-4766



For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated:  8/28/2012

Copyright  2012 National Organization for Rare Disorders, Inc.

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