Types of Hemophilia

Type A

Hemophilia type A is caused by a missing or defective factor VIII protein. It has three stages depending on the ratio of clotting protein in the blood: mild, moderate, and severe. People with hemophilia A bleed longer than others, internally or externally. Those with mild cases generally bleed only after serious injury, trauma, or surgery. Often, the disease is diagnosed after one of these situations due to prolonged bleeding, and the first episode may occur only in adulthood.

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Type B

Hemophilia type B is caused by a missing or defective factor IX clotting protein. This type is rarer than type A; however, the severity and symptoms are similar. A subtype of hemophilia type B, known as hemophilia B Leyden, causes episodes of excessive bleeding in childhood, which gradually disappear after puberty.

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Type C

Hemophilia type C is caused by a missing or defective factor XI clotting protein. Unlike hemophilia A and B, symptoms don’t correlate with factor XI levels in the blood. People with lower levels may bleed less than those with higher levels of the clotting protein. Patients often experience nosebleeds or soft tissue bleeds, as well as hemorrhaging after tooth extraction. Factor XI concentrates are unavailable in the U.S. as yet, so doctors normally treat hemophilia C with fresh frozen plasma.

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Acquired Hemophilia

Acquired hemophilia is an autoimmune disorder in which the body’s immune system mistakes self-proteins as foreign and starts producing antibodies against them. In this type of hemophilia, the immune system mistakes the blood clotting protein called factor VIII as foreign and starts to produce antibodies against it. As a result, factor VIII activity is inhibited, which leads to excessive bleeding.

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