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Christmas' factor

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A thromboplastin activator (catalysing factor) present in blood plasma which is necessary for normal formation of thromboplastin, and thus for normal coagulation. When Christmas Factor is missing from the blood, it causes Christmas’ Disease. The name came from the patient in whom it was first determined that the hereditary haemophilia B was a different disease from the classical hereditary haemophilia caused by the absence of another clotting factor, Factor VIII.

We thank John Smith III for information submitted.


  • R. A. Biggs, A. S. Douglas, R. G. MacFarlane, J. V. Dacie, W. R. Pittney, C. Merskey and J. R. O’Brien:
    Christmas disease, a condition previously mistaken for haemophilia.
    British Medical Journal, London, 1952: 1378-1382.

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