Understanding Hemophilia B

Understanding Hemophilia B

A Rare Bleeding Condition1-6

All forms of hemophilia are caused by a deficiency in a specific clotting factor. Hemophilia B is a rare form of hemophilia caused by a deficiency of clotting factor IX; therefore, it is also known as factor IX (FIX) deficiency. It is also referred to as Christmas disease because it was originally named after Stephen Christmas, a young British boy who was the first person diagnosed with the disorder.

Hemophilia B is a rare disease affecting about 1 in 25,000 US male births. Hemophilia B is thought to affect approximately 20% of people with hemophilia.

Factors are specialized proteins circulating in the blood that work together in a chain reaction to form clots. Missing even one clotting factor can prevent clotting or cause it to be impaired.

The Genetic Basis of Hemophilia B3

Hemophilia B, like hemophilia A, is a genetic condition that affects males almost exclusively. Because hemophilia B is an inherited disorder, the gene responsible for hemophilia is almost always passed down from parent to child. In approximately 30% of cases, there is no family history of hemophilia B, which means it resulted from a spontaneous gene mutation.

To understand how hemophilia B is passed through families, it's important to understand the basics of the underlying genetics. Everyone inherits two sex chromosomes, one from each parent. Males inherit one X chromosome and one Y chromosome, while all females inherit two X chromosomes. Hemophilia B is what is called an X-linked disorder, because the gene responsible for the missing factor is located on the X chromosome. This means males with the gene will always show symptoms of the disorder, but females can be carriers who have no symptoms because they still have one X chromosome without the gene for hemophilia B.

Current Hemophilia B Treatment Options3,7

Treatment options for patients with hemophilia B include RICE (rest, ice, compression, elevation) and replacing the missing factor, factor IX, in order for a clot to form. Factor replacement treatment is always given as an injection or an infusion directly into a vein.

Factor products can be made from human blood products like donated plasma, or by using synthetic non-blood products in a lab to make what is called "recombinant factor." Your doctor or your HTC will help you decide which is right for you.

It is important to work with your clinician or HTC to find the treatment plan that is right for you. Recognizing different types of bleeds, like muscle or joint bleeds, can help you keep track of how many and what kind you experience, so you can work with your HTC to manage your hemophilia. Making a plan and sticking to it can help you reduce the number of bleeds you have. Find valuable resources to get you started and help you stick with your plan no matter where you are in your hemophilia journey.

Inhibitors and Hemophilia B3,8,9

Hemophilia B causes the body to produce little or no factor IX, which is necessary for the formation of blood clots. Because factor IX isn't made naturally by the body in hemophilia B patients, replacement factor treatment is needed for some patients. An inhibitor is a rare complication that can occur in people with hemophilia B in response to factor replacement treatment. Inhibitors are far less common in people with hemophilia B than they are in hemophilia A.

Inhibitors, though rare in people with hemophilia B, can happen when the body's own immune system doesn't recognize the replacement factor treatment and starts to form antibodies against it. These antibodies are known as "inhibitors" because they prevent the replacement factor from working properly and preventing clot formation.

References

  1. Hemophilia A and B. Indiana Hemophilia & Thrombosis Center, Inc. website. http://www.ihtc.org/patient/blood-disorders/bleeding-disorders/hemophilia-a-and-b/. Accessed January 26, 2017.
  2. Frequently Asked Questions About Hemophilia. National Hemophilia Foundation. https://www.hemophilia.org/walk/docs/NHFFAQs.pdf. Accessed January 26, 2017.
  3. Hemophilia B (Factor IX). National Hemophilia Foundation website. https://www.hemophilia.org/Bleeding-Disorders/Types-of-Bleeding-Disorders/Hemophilia-B. Accessed January 26, 2017.
  4. Philip J, Sarkar RS, Kumar S, et al. Factor IX deficiency (Christmas disease). Med J Armed Forces India. 2012;68:379–380.
  5. What is a Bleeding Disorder? National Hemophilia Foundation website. https://www.hemophilia.org/Bleeding-Disorders/What-is-a-Bleeding-Disorder. Accessed January 26, 2017.
  6. Factor XIII Deficiency. National Organization of Rare Disorders website. https://rarediseases.org/rare-diseases/factor-xiii-deficiency/. Accessed January 26, 2017.
  7. Reviewing Principles of R.I.C.E. London Health Sciences Center website. http://www.lhsc.on.ca/Patients_Families_Visitors/Bleeding_Disorders/Physiotherapy/RICE.htm. Accessed January 26, 2017.
  8. Complications. National Hemophilia Foundation website. https://www.hemophilia.org/Bleeding-Disorders/Inhibitors-Other-Complications. Accessed January 26, 2017.
  9. Hemophilia Facts. Centers for Disease Control and Prevention website. www.cdc.gov/ncbddd/hemophilia/facts.html Accessed January 26, 2017.

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