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Hemophilia B

It is possible that the main title of the report Hemophilia B 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.


  • Christmas disease
  • Factor IX deficiency
  • royal disease

Disorder Subdivisions

  • None

General Discussion

Hemophilia B is a rare genetic bleeding disorder in which affected individuals have insufficient levels of a blood protein called factor IX. Factor IX is a clotting factor. Clotting factors are specialized proteins needed for blood clotting, the process by which blood seals a wound to stop bleeding. Individuals with hemophilia B do not bleed faster than unaffected individuals, they bleed longer. This is because they are missing a protein involved in blood clotting and are unable to effectively stop the flow of blood from the site of a wound. This is sometimes referred to as prolonged bleeding or a bleeding episode.

Hemophilia B is classified as mild, moderate or severe. In mild cases, bleeding symptoms may occur only after surgery, major injury or a dental procedure. In some moderate and most severe cases, bleeding symptoms may occur after a minor injury or spontaneously with no known cause.

Hemophilia B is caused by disruptions, or changes, to the factor IX gene. The factor IX gene is located on one of two sex chromosomes - the X chromosome. Males have one X chromosome and one Y chromosome and thus one altered copy of the factor IX gene in a male is enough to cause him to have hemophilia. Females have two X chromosomes and must have two altered copies of the factor IX gene to have hemophilia. Hemophilia in females is very uncommon and therefore the disorder almost always affects males. It is possible for some females with only one altered copy of the factor IX gene to have bleeding symptoms most often seen in mild hemophilia.

Hemophilia B is the second most common type of hemophilia and is estimated to occur in about 1 in 25,000 male births. It affects all races equally. Hemophilia B is also known as factor IX deficiency or Christmas disease. The disorder was first reported in the medical literature in 1952 in a patient with the name of Stephen Christmas. The most famous family with hemophilia B was that of Queen Victoria of England. Through her descendants, the disorder was passed down to the royal families of Germany, Spain and Russia and thus hemophilia B is also known as the "royal disease."

Although the focus of this report is the genetic, or inherited, form of hemophilia B, it should be noted that another form called acquired hemophilia B can develop later in life (see "Related Disorders" section below). An individual with acquired hemophilia B is not born with the condition. Acquired hemophilia B is caused by the body's production of antibodies against its own factor IX protein. The factor IX antibodies destroy circulating factor IX in the blood causing bleeding symptoms. Acquired hemophilia B is extremely rare; most cases of acquired hemophilia are in those with hemophilia A.


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 1987, 1988, 1989, 1995, 1996, 2000, 2007, 2008, 2012 National Organization for Rare Disorders, Inc.

WebMD Medical Reference from the National Organization for Rare Disorders

Last Updated: 8/, 015
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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