'Haemophilia B' (also spelled 'Hemophilia B' or 'Hæmophilia B') is a
blood clotting disorder caused by a
mutation of the
Factor IX gene. It is the second most common form of
haemophilia, rarer than
haemophilia A. It is sometimes called 'Christmas disease' after
Stephen Christmas, the first patient described with this disease.
[1] In addition, the first report of its identification was published in the Christmas edition of the
British Medical Journal.
[2]
Treatment
Treatment (bleeding prophylaxis) is by intravenous infusion of factor IX.
Genetics
The factor IX gene is located on the
X chromosome (Xq27.1-q27.2). It is inherited
X-linked recessive, which explains why - as in haemophilia A - mostly males are generally affected.
Pathophysiology
Factor IX deficiency leads to an increased propensity for
haemorrhage. This is in response to mild trauma or even spontaneously, such as in joints (
haemarthrosis) or muscles.
Reference
1.
2. Biggs RA, Douglas AS, MacFarlane RG, Dacie JV, Pittney WR, Merskey C, O'Brien JR. ''Christmas disease: a condition previously mistaken for haemophilia.'' Br Med J 1952;2:1378-1382. PMID 12997790.
See also
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Haemophilia
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Haemophilia A
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Haemophilia C
External links
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Haemophilia: What is it? at
CSHL ''Your Genes, Your Health''
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