Guide To Diagnosing And Treating Christmas Disease (Hemophilia B)

Christmas disease, also called hemophilia B, is an uncommon bleeding disorder that causes a deficiency of a protein called coagulation factor IX, which is essential for blood clotting. Hemophilia B is caused by a mutation in the gene that encodes instructions for the production of factor IX. Healthy blood clotting requires many clotting factors, including factor IX, to prevent excessive blood loss. Affected individuals bleed longer than unaffected individuals. Factor IX activity level is what determines hemophilia B severity. Mild hemophilia B falls between five to forty percent of normal levels, and severe hemophilia B is one percent or less of normal levels.