What Is Hemophilia?
Hemophilia is a rare, inherited bleeding disorder in which the blood does not clot normally. People who have it may bleed for a longer period of time following an injury or accident. People with the disorder 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 it usually occurs only in males, there are very rare exceptions in which a female will have the blood disorder.

People with hemophilia have problems with certain proteins in their blood, called clotting factors. Clotting factors help blood to clot. Hemophilia can occur if there is a low level of one of the clotting factors or if a clotting factor 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.

What Causes Hemophilia?
Hemophilia is an inherited disease. Hemophilia is caused by a defect in one of the genes that determines how the body makes blood clotting factors 8 and 9. These genes are located on the X chromosomes, which determine whether a baby is a boy or girl.

F8 and F9 Genes
Mutations in the F8 or F9 genes cause hemophilia. Mutations in the F8 gene cause hemophilia A, while hemophilia B is caused by mutations in the F9 gene.

The proteins made by these genes play a critical role in the process of blood clotting. Mutations in either gene prevent clots from forming in response to injury, which lead to excessive bleeding that can be difficult to control.

Signs and Symptoms of Hemophilia: An Overview
Hemophilia is a rare, inherited bleeding disorder. Approximately 18,000 people in the United States have this disorder. 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). Common symptoms of hemophilia include bleeding and bruising.

Hemophilia Treatment: Sources of Clotting Factors

The clotting factor concentrates that are used in replacement therapy come from two sources:

• Blood from human donors

• Lab-produced clotting factors called "recombinant" factors, which are not made from human blood.

Clotting factors from either source are generally considered safe. However, recombinant factors cannot carry viruses and are usually preferred for treating hemophilia. Recombinant clotting factors work the same as natural clotting factors.

Infusions need to be given once daily or more frequently when treatment has begun because half of the activity of factor 8 is gone in 8 to 12 hours and half of the activity of factor 9 is gone in 12 to 24 hours.

Clotting factors used in replacement therapy today are powerful and easy to store, mix, and use at home


Hemophilia Treatment: Replacement Therapy to Prevent Bleeding

Some people may receive replacement therapy on a regular basis to prevent bleeding. The goal of replacement therapy is to keep the levels of clotting factors in the blood high enough so that bleeding will not occur. This hemophilia treatment is more likely to be used in people with severe cases, and it is often used in children to prevent damage to joints from bleeding.

Preventive replacement therapy can be given on a:

• Long-term basis, usually two to three times a week

• Shorter-term basis, usually every few months

• Short-term basis, usually before participating in an activity that could cause bleeding.