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X-linked recessive inheritance
|Classification and external resources|
|Patient UK||Haemophilia B|
Haemophilia B (or hemophilia B) is a blood clotting disorder caused by a mutation of the factor IX gene, leading to a deficiency of factor IX. It is the second-most common form of haemophilia, rarer than haemophilia A. Haemophilia B was first recognized as a different kind of haemophilia in 1952. It is sometimes called Christmas disease, named after Stephen Christmas, the first patient described with this disease. In addition, the first report of its identification was published in the Christmas edition of the British Medical Journal.
The condition is marked by increased clotting time(3–8 minutes) and bleeding time(2–5 minutes).
The factor IX gene is located on the X chromosome (Xq27.1-q27.2). It is an X-linked recessive trait, which explains why, as in haemophilia A, usually only males are affected. One in 20,000–30,000 males are affected.
In 1990, George Brownlee and Merlin Crossley showed that two sets of genetic mutations were preventing two key proteins from attaching to the DNA of people with a rare and unusual form of haemophilia B – haemophilia B Leyden – where sufferers experience episodes of excessive bleeding in childhood but have few bleeding problems after puberty. This lack of protein attachment to the DNA was thereby turning off the gene that produces clotting factor IX, which prevents excessive bleeding. In 2013, Merlin Crossley discovered the third and final protein causing haemophilia B Leyden.
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Treatment (bleeding prophylaxis) is by intravenous infusion of factor IX. Factor IX has a longer half life than factor VIII (deficient in haemophilia A) and as such factor IX can be transfused less frequently.
In the early years, there were not many treatment options for people with haemophilia B. By the late 1950s and the 1960s, with newfound technology and gradual advances in medicine, pharmaceutical scientists found a way to take the factor IX from fresh frozen plasma(FFP) and give it to those with haemophilia B. Though they found a way to treat the disease, the FFP contained only a small amount of factor IX, requiring large amounts of FFP to treat an actual bleeding episode, which resulted in the patients requiring hospitalization. By the mid-1960s scientists found a way to get a larger amount of factor IX from FFP.By the late 1960s, pharmaceutical scientists found methods to separate the factor IX from plasma, which allows for neatly packaged bottles of factor IX concentrates. With the new development, doctors have a way to dose the amount of factor IX that patients need for bleed episodes. With the rise of factor IX concentrates it became easier for people to get treatment at home.Although these advances in medicine had a significant positive impact on the treatment of haemophilia, there were many complications that came with it. By the early 1980s, scientists discovered that the medicines they had created were transferring blood-borne viruses, such as hepatitis, and HIV, the virus that causes AIDS. With the rise of these deadly viruses, scientists had to find improved methods for screening the blood products they received from donors.In 1982, scientists made a breakthrough in medicine and were able to clone factor IX gene. With this new development it decreased the risk of the many viruses. Although the new factor was created, it wasn't available for haemophilia B patients till 1997.
European royal families
- "Haemophilia B (Factor IX Deficiency) information | Patient". Patient. Retrieved 2016-04-21.
- "Hemophilia B: MedlinePlus Medical Encyclopedia". medlineplus.gov. Retrieved 2016-09-21.
- Biggs R, Douglas AS, MacFarlane RG, Dacie JV, Pitney WR, Merskey C, O'Brien JR (1952). "Christmas disease: a condition previously mistaken for haemophilia". Br Med J. 2 (4799): 1378–82. doi:10.1136/bmj.2.4799.1378. PMC . PMID 12997790.
- Michael Price (8 October 2009). "Case Closed: Famous Royals Suffered From Hemophilia". ScienceNOW Daily News. AAAS. Retrieved 9 October 2009.
- Evgeny I. Rogaev; et al. (8 October 2009). "Genotype Analysis Identifies the Cause of the "Royal Disease"". Science. Retrieved 9 October 2009.subscription required
- Konkle, Barbara A.; Josephson, Neil C.; Nakaya Fletcher, Shelley (1 January 1993). "Hemophilia B". GeneReviews(®). University of Washington, Seattle. Retrieved 25 June 2016.update 2014