Hemophilia B (Factor IX)
Hemophilia B is the second most common type of hemophilia. It can also be known as factor IX deficiency, or Christmas disease. It was originally named “Christmas disease” for the first person diagnosed with the disorder back in 1952.
It is largely an inherited disorder in which one of the proteins needed to form blood clots is missing or reduced. In about 30% of cases, there is no family history of the disorder and the condition is the result of a spontaneous gene mutation.
Hemophilia B is far less common than Hemophilia A. Occurring in about one in 25,000 male births, hemophilia B affects about 3,300 individuals in the United States. All races and economic groups are affected equally.
When a person with hemophilia is injured, he does not bleed harder or faster than a person without hemophilia, he bleeds longer. Small cuts or surface bruises are usually not a problem, but more traumatic injuries may result in serious problems and potential disability (called “bleeding episodes”).
Normal plasma levels of FIX range from 50% to 150%. There are different levels of hemophilia: mild, moderate, and severe, depending on the amount of clotting factor in the blood:
People with mild hemophilia have 5% up to 50% of the normal clotting fa