Factor XII (Hageman factor) deficiency

Definition

This is an inherited disorder with no symptoms. It does not cause abnormal bleeding in the affected person, but the blood takes longer than normal to clot (coagulate) in a test tube. It results from a deficiency of the plasma protein factor XII.

Causes, incidence, and risk factors

Factor XII deficiency is a rare hereditary disorder that is usually found when clotting tests are done for routine screening. It is not associated with abnormal bleeding.

Symptoms

There are usually no symptoms.

Signs and tests

• Prolonged partial thromboplastin time
• Abnormal factor XII assay

Treatment

Treatment is generally unnecessary.

Expectations (prognosis)

The outcome is expected to be good without treatment.

Complications

There are usually no complications.

Calling your health care provider

This condition is usually discovered by the health care provider when prolonged clotting is noticed in the process of running other laboratory tests.

Prevention

This is an inherited disorder. There is no known way to prevent it.

Illustrations

Blood clots