Hemophilia A & B

Hemophilia is an inherited, genetic disease caused by a deficiency of clotting factor in the blood which results in continuous and often spontaneous bleeding, even from mild injuries and bruising. More serious internal bleeding can spread to joints and surrounding tissue, causing severe pain and swelling. Recurring severe episodes can lead to debilitating joint function.

Hemophilia A is the most common form of hemophilia and is caused by a lack of deficiency of factor VIII, a blood plasma protein. Hemophilia B is less common and is caused by deficiency of the factor IX blood plasma protein.

Hemophilia is found equally among every race, social class and cultural background, but does occur most often in men, though occurs in women as well. Approximately 1 in 5,000 men in the United States has hemophilia. About 20,000 Americans have hemophilia. And although inherited through mothers, nearly 30% of all hemophilia occurs without a family history.

While there is no cure, there is treatment. Persons with hemophilia may be infused with human or genetically engineered clotting factor. With current treatments, a person with hemophilia generally has a normal life expectancy.

Levels of Severity

The severity of hemophilia is determined by the level of clotting activity of factor VIII or IX in the blood. There are three levels of severity: mild, moderate, and severe. The following table shows the range of factor VIII and factor IX activity:

Level Hemophilia Severity Percentage of normal factor activity in blood Number of international units (IU) per milliliter (ml) of whole blood
Normal range 50%-200% 0.5–2 IU
Subnormal range, but bleeding After injury is unlikely 25%-49% 0.25–0.49 IU
Mild hemophilia 6%-24% 0.06–0.24 IU
Moderate hemophilia 1%-5% 0.01 –0.05 IU
Severe hemophilia less than 1% less than 0.01 IU