Hemophilia A is the most common type of hemophilia, a rare, inherited bleeding disorder in which the blood does not clot normally. Approximately 9 out of 10 people with hemophilia have this type. Also known as "classic hemophilia," this form of hemophilia is caused by a mutation in one of the genes that determines how the body makes clotting factor 8. People with this condition may have a low level of clotting factor 8, or it may be missing altogether. The main treatment for this disorder is replacement therapy.
What Is Hemophilia A?
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:
- Hemophilia A
- Hemophilia B.
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.