Hemophilia B is a hereditary bleeding disorder caused by a lack of blood clotting factor IX. People with hemophilia experience frequent bruising and prolonged bleeding.
What Is Hemophilia B?
Hemophilia is a genetic disorder caused by missing or dysfunctional proteins, called factors, that are responsible for clotting blood and preventing excessive bleeding.
There are two main types of hemophilia — hemophilia A and hemophilia B. Although the two types have very similar signs and symptoms, they are caused by mutations in different genes. Hemophilia B, the topic of this article, is the result of a genetic mutation (change in a gene) that affects the functioning of clotting factor IX.
The primary method of treatment for hemophilia B is providing the necessary clotting factors intravenously or topically to wounds.
You should visit your primary care physician who will refer you to a hemophilia treatment center. Treatment is with medication and avoidance of trauma that can cause uncontrollable bleeding.
Hemophilia B Symptoms
As discussed, the primary symptom of hemophilia B is prolonged and/or spontaneous bleeding. However, the extent of bleeding and symptoms will vary depending on the level of factor IX. If your clotting-factor level is only mildly reduced, bleeding may occur only after surgery or significant trauma. However, if the deficiency is severe one may experience bleeding at random times in the absence of trauma.
Signs and symptoms of spontaneous bleeding include:
Hemophilia B Causes
Hemophilia B is caused by genetic mutations that are most commonly passed from parent to offspring. However, about one-third of cases are caused by , meaning there is not a component of inheritance to the development of the disease.
How this condition is inherited
Hemophilia B is inherited in an X-linked recessive pattern and most commonly happens in males because the defective gene is passed via the mother's X chromosome. Since females inherit two X chromosomes, if one of the X chromosomes is defective, the normal X chromosome can still make a normally functioning gene and protein. However, since males only have one X chromosome, if it is defective there is no normal X chromosome to compensate. In addition to this, a characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
Why females are likely to be carriers
Though females rarely display the full disease and its symptoms, they can be carriers. Carriers are women who have one altered X chromosome. Carrier females usually have about half the amount of factor IX and are usually without symptoms. However, in some cases, carrier women have less than half the normal amount of factor IX. These individuals are at higher risk for abnormal bleeding than the general population.
How common is this condition
Treatment Options and Prevention for Hemophilia B
The main treatment for hemophilia B involves receiving a replacement of the clotting factor IX, given through a IV placed in a vein.
There are also other therapies for hemophilia B, which include:
- Desmopressin (DDAVP): DDAVP is a hormone that can stimulate the body to release more clotting factor, and is often used in milder cases of hemophilia B.
- Clot-preserving medications (antifibrinolytics): These medications, that help prevent clots from breaking down, help the limited clotting factor an individual does have work less.
- Fibrin sealants: These medications can be applied directly to wound sites to promote clotting and healing. Fibrin sealants are especially useful after dental procedures.
- First aid for minor cuts: Using pressure and a bandage will generally take care of the bleeding. For small areas of bleeding beneath the skin, use an ice pack. Ice pops can be used to slow down minor bleeding in the mouth.
- Bleeding into the brain: A moderate bump on the head can cause bleeding into the brain. Though this is a rare occurrence, it is one of the most serious complications of hemophilia B.
- Deep internal bleeding: Bleeding that occurs in the deep muscles of the body can result in limb swelling and can compress nerves, leading to numbness or pain.
- Joint damage: Internal bleeding can also put pressure on the joints, especially the knees, causing severe pain. Bleeding into the knee joint is called hemarthrosis, and if untreated may cause arthritis or physical destruction to the joint.
- People with hemophilia are more likely to have blood transfusions, increasing their risk of receiving contaminated blood products. Blood products became far safer after the mid-1980s due to the screening of donated blood for hepatitis and HIV.
- Adverse reaction to clotting factor treatment: In some people with hemophilia, the immune system has a reaction to the clotting factors used to treat bleeding. When this happens, the immune system develops proteins (inhibitors) that inactivate the clotting factors, making treatment less effective.
When to Seek Further Consultation for Hemophilia B
If you have hemophilia B and experience any of the symptoms below, call 911 immediately. These may be signs of serious bleeding in the brain:
- Painful, prolonged headache
- Repeated vomiting
- Sleepiness or lethargy
- Double vision
- Sudden weakness or clumsiness
- Convulsions or seizures
In addition, if you experience an injury where the bleeding will not stop or your joints become painful, swollen, or warm to the touch, seek medical attention promptly as well.
Questions Your Doctor May Ask to Determine Hemophilia B
- How severe is your shoulder pain?
- Is your shoulder pain constant or come-and-go?
- Is your shoulder pain getting better or worse?
- Do you have a history of heart disease?
- Have you ever been diagnosed with diabetes?
Self-diagnose with our free if you answer yes on any of these questions.
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- Guidelines of the management of hemophilia. 2nd ed. Montreal, Quebec. Blackwell Publishing; 2012.
- Transfusion safety. NIH: Research Portfolio Online Reporting Tools (RePORT). Published June 30, 2018.