About Hemophilia

Hemophilia is an inherited, x-linked bleeding disorder (a.k.a., “blood clotting disorder”) caused by the absence or inactivity of an essential blood clotting protein called “factor.” There are at least 10 clotting factor proteins in the blood that act together to form a clot. A deficiency of specific clotting factors causes a breakdown in the chain of events that make up the blood’s normal clotting process.

Contrary to popular belief, people with hemophilia do not bleed more or faster than people without hemophilia, but they do bleed longer. The blood’s inability to form a stable clot can lead to episodes of prolonged bleeding, most commonly into joints, but also into muscle, soft tissue and vital organs. Minor cuts and scrapes on the surface of the skin can usually be treated with pressure and a bandage.

There are several types of clotting factors, and they work together with platelets to help the blood clot. Platelets are small pieces of blood cells that are formed in the bone marrow and play a major role in blood clotting.

When blood vessels are injured, clotting factors help the platelets stick together to plug cuts and breaks at the site of the injury to stop the bleeding. Without clotting factors, normal blood clotting can’t take place. Most people with hemophilia need infusions of replacement clotting factor to stop bleeding and manage their condition.

There are two main types of hemophilia. If you have hemophilia A, you have little to no clotting factor VIII. About 8 out of 10 people with hemophilia have type A. If you have hemophilia B, you’re missing or have low levels of clotting factor IX.

Hemophilia can be mild, moderate, or severe, depending on how much clotting factor is in the blood. About 7 out of 10 people who have hemophilia A have the severe form of the disorder. People who don’t have hemophilia have a factor VIII activity of 100 percent; people who have severe hemophilia A have a factor VIII activity of less than 1 percent.

In addition to being inherited, hemophilia also can be acquired, which means that you can develop it during your lifetime. It can develop if your body forms antibodies to the clotting factors in your bloodstream. The antibodies can block the clotting factors from working. Only inherited hemophilia is discussed on this website.

As an x-linked genetic trait, hemophilia affects males almost exclusively, with very few exceptions. In the United States, there are approximately 18,000 people living with hemophilia (~ 1:7500 males). Each year, about 400 babies are born with the disorder.