Hemophilia B is a hereditary bleeding disorder caused by a lack of blood clotting factor IX. Without enough factor IX, the blood cannot clot properly to control bleeding.
Christmas disease; Factor IX hemophilia
Hemophilia B is caused by an inherited X-linked recessive trait, with the defective gene located on the X chromosome.
Females have two copies of the X chromosome. If the factor IX gene on one chromosome does not work, the gene on the other chromosome can do the job of making enough factor IX.
Males have only one X chromosome. If the factor IX gene is missing on a boy's X chromosome, he will have Hemophilia B. For this reason, most people with hemophilia B are male.
If a woman has a defective factor IX gene, she is considered a carrier. This means the defective gene can be passed down to her children. Boys born to such women have a 50% chance of having hemophilia B. Their daughters have a 50% chance of being a carrier.
All female children of men with hemophilia carry the defective gene.
Risk factors for hemophilia B include:
- Family history of bleeding
- Being male
The severity of symptoms can vary. Bleeding is the main symptom. It is often first seen when the an infant is circumcised. Other bleeding problems usually show up when the infant starts crawling and walking.
Mild cases may go unnoticed until later in life. Symptoms may first occur after surgery or injury. Internal bleeding may occur anywhere.
Symptoms can include:
- Bleeding into joints with associated pain and swelling
- Blood in the urine or stool
- Gastrointestinal tract and urinary tract hemorrhage
- Prolonged bleeding from cuts, tooth extraction, and surgery
- Spontaneous bleeding
Exams and Tests
If you are the first person in the family to have a suspected bleeding disorder, your doctor will order a series of tests called a coagulation study. Once the specific defect has been identified, other people in your family will need tests to diagnose the disorder.
Tests to diagnose hemophilia B include:
- Partial thromboplastin time (PTT)
- Prothrombin time
- Bleeding time
- Fibrinogen level
- Serum factor IX activity
Treatment includes replacing the missing clotting factor. You will receive factor IX concentrates. How much you get depends on:
- Severity of bleeding
- Site of bleeding
- Your weight and height
To prevent a bleeding crisis, people with hemophilia and their families can be taught to give factor IX concentrates at home at the first signs of bleeding. People with severe forms of the disease may need regular, preventive infusions.
If you have severe hemophilia, you may also need to take factor IX concentrate before surgery or certain types of dental work.
You should get the hepatitis B vaccine. People with hemophilia are more likely to get hepatitis because they may receive blood products.
With treatment, most people with hemophilia are able to lead a relatively normal life.
If you have hemophilia, you should have regular check ups with a hematologist.
Complications can include:
- Long-term joint problems, which may require a joint replacement
- Bleeding in the brain (intracerebral hemorrhage)
- Thrombosis due to treatment
When to Contact a Medical Professional
Call your health care provider if:
- Symptoms of a bleeding disorder develop
- A family member has been diagnosed with hemophilia B
- If you have hemophilia B, and you plan to have children; genetic counseling is available
Genetic counseling may be recommended. Testing can identify women and girls who carry the hemophilia gene.
Testing can be done during pregancy on a baby that is in the mother's womb.
Carcao M, Moorehead P, Lillicrap D. Hemophilia A and B. In: Hoffman R, Benz EJ Jr, Silberstein LE, et al., eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, Pa: Elsevier Saunders; 2012:chap 137.
Scott JP, Montgomer RR. Hereditary clotting factor deficiencies (bleeding disorders). In: Kliegman RM, Stanton BF, St. Geme JW III, et al., eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 470.