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Hemophilia B

Last updated Sept. 25, 2018

Approved by: Maulik P. Purohit MD, MPH

Hemophilia B is a rare inherited genetic disorder that prevents normal blood clot formation, generally in males.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Christmas Disease
  • Functional Factor IX Deficiency
  • Plasma Thromboplastin Component Deficiency

What is Hemophilia B? (Definition/Background Information)

  • Hemophilia B is a rare inherited genetic disorder that prevents normal blood clot formation, generally in males
  • In this bleeding disorder, the clotting factor IX protein levels necessary for blood clotting are either absent or only available in reduced quantities
  • Both the treatment and prognosis for the condition are based on its severity. Often, an individualized treatment plan for Hemophilia B is devised by the healthcare provider. The prognosis is usually good

Who gets Hemophilia B? (Age and Sex Distribution)

  • Hemophilia B occurs in approximately 1 in 25,000-30,000 males
  • This condition usually affects only males because it is an X chromosome-linked disorder. Males have only one X chromosome; thus, if the mutation is present, the disease will develop in them
  • Women will be affected by the disorder only if they inherit two abnormal X chromosomes. Those who inherit only one copy of the mutation do not show any symptoms of the condition and are referred to as carriers
  • All races and ethnic population are prone to Hemophilia B

What are the Risk Factors for Hemophilia B? (Predisposing Factors)

Hemophilia B risk factors include:

  • Previous family history of Hemophilia B
  • Male sex

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your health care provider.

What are the Causes of Hemophilia B? (Etiology)

  • Hemophilia B genetic disorder is either inherited or acquired
  • Causes of Hemophilia B include:
    • A mutation in the FIX gene
    • An acquired factor IX inhibitor (in rare cases)
  • Approximately 30% of Hemophilia B cases occur as spontaneous mutations. This means that no known family history is present as a risk factor
  • Acquired Hemophilia B is extremely rare. Such cases can occur when an individual produces antibodies against clotting factor IX. This results in a deficiency of clotting factor IX in the body

What are the Signs and Symptoms of Hemophilia B?

The signs and symptoms of Hemophilia B vary, depending on the severity of the disorder. These include:

  • Prolonged bleeding after surgical procedures, tooth extractions, circumcision, cuts, etc.
  • Unexplained, excessive bruising, nosebleeds
  • Unexplained blood in urine or feces
  • Internal bleeding, causing pain and swelling of joints
  • Unexplained intracranial bleeding in childbirth (bleeding in the skull)
  • Spontaneous (unprovoked) bleeding

How is Hemophilia B Diagnosed?

Hemophilia B disorder is diagnosed through coagulation studies to pinpoint the specific defect present. The blood tests used for this condition include:

  • Activated partial thromboplastin time (aPTT), prolonged
  • Normal prothrombin time
  • Normal fibrinogen level
  • Clotting factor assays (measures level of factor IX in blood)

Differentiating between severe Hemophilia A and Hemophilia B based on clinical presentation is almost impossible. Though, factor assay tests can help distinguish between the two.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hemophilia B?

The possible complications due to Hemophilia B include:

  • Intracerebral hemorrhage - bleeding in brain
  • Chronic joint problems, due to persistent bleeding into joint space
  • Extreme blood loss in some cases could be fatal

How is Hemophilia B Treated?

Hemophilia B cannot be cured. The treatment is provided on a case-by-case basis, depending on the severity of hemophilia. Treatment plans for the blood clotting disorder may include:

  • Infusion of factor IX concentrates
  • Desmopressin acetate (DDAVP), to treat small bleeds
  • Blood transfusions
  • Hemophilia B vaccination is administered if the need for blood transfusion is frequent

How can Hemophilia B be Prevented?

  • Currently, there are no specific methods or guidelines to prevent Hemophilia B genetic condition
  • Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
  • If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
  • Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Hemophilia B? (Outcomes/Resolutions)

  • The prognosis of Hemophilia B is dependent on the severity of the disease and an individual’s response to therapy. However, generally the prognosis is fairly good
  • With frequent checkups and efficient treatment, the affected individuals can lead a normal life

Additional and Relevant Useful Information for Hemophilia B:

Hemophilia A is a genetic deficiency of clotting factor VIII, which causes increased bleeding, generally in males. The clotting factor VIII itself may be abnormal or normal; when normal, factor VIII levels vary from ‘essentially absent’ to ‘moderately reduced’.

The following article links will help you understand prothrombin time & international normalized ratio (PT/INR) and partial thromboplastin time (PTT) tests.



What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: June 15, 2014
Last updated: Sept. 25, 2018