What Is Factor IX Deficiency?

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  • Written By: Mary McMahon
  • Edited By: Shereen Skola
  • Last Modified Date: 05 November 2018
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Factor IX deficiency refers to an inadequate supply of one of the blood’s clotting factors that causes a condition called hemophilia B. After hemophilia A, it is the most common form of this bleeding disorder, and can present with varying severity. Patients with a factor IX deficiency will bleed longer than other people because their blood doesn’t clot as quickly. The condition can cause problems with surgeries and certain types of injuries, as well as complications caused by internal bleeding.

This is a genetic condition, usually caused by inheritance although sometimes it is the result of a spontaneous mutation. It is an X-linked trait, meaning that it is carried on the X chromosome. As a result, men are much more likely to develop factor IX deficiency, because they only inherit one copy of the chromosome involved. Women are more likely to be carriers; the healthy copy of the gene produces enough factor IX to meet their needs, but they can pass on the defective gene when they have children.


Patients may also know hemophilia B as Christmas disease, thanks to the alternate name for factor IX. Stephen Christmas was the first patient in whom the deficiency was identified, and some medical providers refer to factor IX as Christmas factor in his honor. The specifics of the gene can vary, which means some cases are more mild and may not be noticed until adulthood, when a man appears to bleed longer than is usual. In other cases, issues like bruising and excessive bleeding are apparent at birth or early childhood.

Excessive bleeding can be a concern with surface injuries and medical procedures that may cause bleeding, like dental work. It is also an issue for the joints, because bleeding inside the joints may cause swelling and irritation. Over time, this could cause arthritis, which may onset early in life. Internal bleeding can also damage the organs or cause swelling in the brain. For these reasons, a patient with factor IX deficiency may need to be carefully evaluated after any traumatic injuries to determine if medical complications have developed.

Treatment for factor IX deficiency involves infusions of factor IX to make up for the body’s lack of ability to produce it. These are made from treated blood products which are carefully screened to eliminate donated products that might contain infectious organisms. The level of treatment needed can depend on the severity of the case and how well the patient responds.



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