Hemophilia B

Other Names: Christmas disease; Factor IX deficiency; HEM B

Hemophilia B is a bleeding disorder that slows the blood clotting process. People with this disorder experience prolonged bleeding or oozing following an injury or surgery. In severe cases of hemophilia, heavy bleeding occurs after minor injury or even in the absence of injury. Serious complications can result from bleeding into the joints, muscles, brain, or other internal organs. Milder forms may not become apparent until abnormal bleeding occurs following surgery or a serious injury. People with an unusual form of hemophilia B, known as hemophilia B Leyden, experience episodes of excessive bleeding in childhood but have few bleeding problems after puberty.

Cause

Mutations in the F9 gene cause hemophilia B. A related protein, coagulation factor IX, is produced from the F9 gene.so factor IX deficiency causes hemophilia B.

Coagulation (FIX is on left)

Coagulation factors are proteins that work together in the blood clotting process. After an injury, blood clots protect the body by sealing off damaged blood vessels and preventing excessive blood loss. Mutations in the F9 gene lead to the production of an abnormal version of coagulation factor IX, or reduce the amount of one of these proteins. The altered or missing protein cannot participate effectively in the blood clotting process. As a result, blood clots cannot form properly in response to injury. These problems with blood clotting lead to continuous bleeding that can be difficult to control. The mutations that cause severe hemophilia almost completely eliminate the activity of coagulation factor IX. The mutations responsible for mild and moderate hemophilia reduce but do not eliminate the activity of one of these proteins.

Inheritance

X-linked recessive inheritance

Hemophilia B is inherited in an X-linked recessive pattern and is caused by mutations in the F9 gene.

Symptoms

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

• Cephalohematoma
• Delayed onset bleeding
• Hematuria(Blood in urine)
• Intracranial hemorrhage(Bleeding within the skull)
• Intramuscular hematoma
• Joint hemorrhage(Bleeding within a joint)
• Menometrorrhagia
• Poor wound healing
• Prolonged bleeding after dental extraction
• Prolonged bleeding after surgery(Excessive bleeding during surgery)
• Prolonged bleeding time
• Prolonged partial thromboplastin time
• Reduced factor IX activity
• Spontaneous, recurrent epistaxis(Recurring nosebleed)

Diagnosis

The diagnosis for hemophilia B can be done via the following tests/methods:

• Coagulation screening test
• Bleeding scores
• Coagulation factor assays

The differential diagnosis for this inherited condition is the following: hemophilia A, factor XI deficiency, von Willebrand disease, fibrinogen disorders and Bernard–Soulier syndrome

Treatment

Treatment is given intermittently, when there is significant bleeding. It includes intravenous infusion of factor IX and/or blood transfusions. NSAIDS should be avoided once the diagnosis is made since they can exacerbate a bleeding episode. Any surgical procedure should be done with concomitant tranexamic acid.

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition.

• Coagulation Factor IX (human) (Brand name: AlphaNine)For use as replacement therapy in patients with hemophilia B for the prevention and control of bleeding episodes and during surgery to correct defective hemostasis.
• Coagulation factor IX (recombinant), Fc fusion protein (Brand name: Alprolix) Adults and children with Hemophilia B for control and prevention of bleeding episodes, perioperative management, and routine prophylaxis to prevent or reduce the frequency of bleeding episodes.
• Coagulation Factor IX (Recombinant) (Brand name: BeneFix®)For the control and prevention of hemorrhagic episodes in patients with hemophilia B (congenital factor IX deficiency and Christmas disease), including control and prevention of bleeding in surgical settings.
• Coagulation Factor IX (Brand name: Mononine)Prevention and control of bleeding in factor IX deficiency, also known as hemophilia B or Christmas disease.
• Coagulation Factor VIIa(Recombinant) (Brand name: NovoSeven RT)NovoSeven RT was approved for the prevention of bleeding in surgical interventions or invasive procedures in hemophilia A or B patients with inhibitors to Factor VIII or Factor IX.

Recombinant fusion protein linking coagulation factor IX with albumin (Brand name: rIX-FP) Coagulation factor IX (recombinant) (Brand name: Rixubis)Adults with Hemophilia B for routine prophylaxis to prevent or reduce the frequency of bleeding episodes.

NIH genetic and rare disease info

• NIH info on Hemophilia B

Hemophilia B is a rare disease.

Hemophilia B Resources
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