Are there different types of hemophilia?

People with hemophilia can have different types of hemophilia depending on which factor does not work in their blood. There are at least 14 factors in the blood. Any one of them may not work properly in someone with hemophilia. This is important to know, because different types of hemophilia require different medicines.

Remember our relay race? Each of the 14 factors passes along a blood-clotting message to the next factor, until the last factor signals the body to make a fibrin net to clot the blood and stop the bleeding. If any of the factors does not work properly - and must drop out of the race -the message to make the fibrin net does not get passed to the last factor.  Without the message, the fibrin net does not get made, the platelet plug falls out and bleeding continues.

In most people with hemophilia, factor VIII is missing or does not work correctly. All the other "runners" hand off the directions for blood clotting until the message reaches factor VIll. But if factor VIll is missing, it can't read the message or complete the directions.  This is known as factor  VIII deficiency or hemophilia A. Factor  IX deficiency is the second most common type of hemophilia. Factor IX is the "runner" that passes the directions to factor VIll.  This hemophilia is also known as hemophilia B, or "Christmas"  disease.

People with hemophilia A must receive medicine containing factor VIII to replace the factor Vill that does not work in their blood. People with hemophilia B must receive medicine containing factor IX to replace the factor IX that does not work in their blood.

About 80% of people with hemophilia have hemophilia A. About 20% of people with hemophilia have hemophilia B. There are people with other factor deficiencies, like factor VIl or factor XIII. Some of these other factor deficiencies are so rare that there are only a few known cases in the world.

Adapted from Tell Them the Facts! By Laureen A. Kelley, 1995