Hemophilia A: An Introduction
Hemophilia is a rare, inherited bleeding disorder in which the blood does not clot normally. People with hemophilia may bleed for a longer period of time following an injury or accident. They may also bleed internally, especially in the joints such as the knees, ankles, and elbows.
Approximately 18,000 people in the United States have hemophilia, and about 400 babies are born each year with this disorder in the U.S. Although hemophilia usually occurs only in males, there are very rare exceptions in which a female will have hemophilia.
There are two main types of hemophilia:
Approximately 9 out of 10 people with hemophilia have type A. People with hemophilia A have a problem with certain proteins in the blood called clotting factors. Clotting factors help blood clot. Hemophilia A can occur if there is a low level of one of the clotting factors or if a clotting factor is missing altogether.
Hemophilia A: Understanding Clotting and Clotting Factors
An injury (like a cut) to a blood vessel causes a complex chain of events that will result in a blood clot. This is called the clotting process, which is also known as blood coagulation. Clotting is your body's reaction to bleeding to keep you from losing too much blood. Losing too much blood can be life threatening and can damage your internal organs.
Clotting factors are proteins in the blood that work with platelets -- small blood cell fragments -- to help the blood to clot. When blood vessels are damaged, clotting factors help the platelets stick together to plug cuts and breaks at the site of the injury.
In people with
hemophilia, blood does not clot as it should due to missing or low levels of one of these clotting factors. If this occurs, there may be heavy blood loss or injured body tissues and organs, which can result in permanent damage or even death.
Hemophilia A is caused by a defect (mutation) in one of the genes that determines how the body makes certain blood-clotting factors. The gene is located on the X chromosome and is called the F8 gene. The F8 gene makes factor 8 (VIII) protein, which is one type of the blood-clotting factor.
This mutation of the F8 gene prevent clots from forming in response to injury, which leads to excessive bleeding that can be difficult to control.
(Click Causes of Hemophilia to learn more about what causes hemophilia A and how hemophilia A is inherited.)
Common Symptoms of Hemophilia A
The major signs and symptoms of
hemophilia A are bleeding and bruising.
Bleeding often occurs internally in joints and muscles. If bleeding in the brain occurs, it is considered a medical emergency.
Hemophilia A symptoms can be:
The severity of hemophilia symptoms is determined by the amount of clotting factor in the blood. Most people (about 7 out of 10) with hemophilia A have the severe form. People who do not have hemophilia have a factor 8 activity of 100 percent; people who have severe hemophilia A have a factor 8 activity of less than 1 percent.
A doctor making a hemophilia A diagnosis will usually need to:
- Review the patient's personal and family medical history
- Perform a physical examination
- Order blood tests.
The tests will indicate:
- Whether you have a bleeding problem
- If the bleeding problem is due to hemophilia A or another cause
- How severe the disorder is.
Treatment for Hemophilia A
The main treatment for
hemophilia A is replacement therapy. Replacement therapy involves injections of the low or missing clotting factors directly into the bloodstream. In the case of hemophilia A, the missing factor injected will be factor 8 (VIII).
Replacement therapy can be used on a long-term basis to prevent bleeding. People with severe hemophilia are more likely to receive this type of preventive replacement therapy. Replacement therapy can also be given on demand (as needed) to stop bleeding when it occurs. This therapy is more common in those with milder hemophilia A.
Early treatment for bleeding is important to prevent or limit damage to joints, muscles, or other parts of the body.
Replacement therapy is often done at home. Home hemophilia A treatment has many benefits. However, it is important to be trained to do home infusions properly and safely.
Exercise is important for children and adults living with hemophilia A. Talk with your doctor about the type of exercise that is best for you or for your child and what to do to prevent injuries.
If you or your child has hemophilia, learn as much as you can about the disorder and if possible, join a support group.
Hemophilia treatment centers (HTCs) are located in many areas of the United States. These centers can provide treatment, education, and support to hemophilia A patients, their families, and their healthcare providers.
How Common Is Hemophilia A?
Hemophilia A is the most common type of hemophilia, affecting 1 in 5,000 to 10,000 males worldwide.
Other Names for Hemophilia A
Other names for hemophilia A include:
- Classic hemophilia
- Factor 8 (VIII) deficiency.
Hemophilia A: Summary of Key Points
Key information about hemophilia A includes the following:
- Hemophilia A is the most common type of hemophilia, which is a rare, inherited bleeding disorder.
- Hemophilia A almost always occurs in males.
- A baby born with hemophilia A has a problem with certain proteins in the blood, called factor 8 clotting factor. Clotting factors helps blood clot.
- Hemophilia A can be due to a low level of clotting factors or due to a clotting factor that is completely missing.
- When clotting factors are missing, or your body does not have enough clotting factors, it can take a long time for your blood to clot after an injury or accident. Bleeding often occurs internally.
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