Factor XII (Hageman factor) deficiency

This is an inherited disorder that causes prolonged clotting (coagulation) of blood in a test tube without a clinical bleeding tendency, and results from a deficiency of the plasma protein factor XII.

Causes, incidence, and risk factors
Factor XII deficiency is a hrare ereditary disorder that is usually found when clotting tests are done for routine screening. It is not associated with abnormal bleeding.

There are usually no symptoms.

Signs and tests

  • Prolonged partial thromboplastin time  
  • Abnormal factor XII assay

Treatment is generally unnecessary.

Expectations (prognosis)
The outcome is expected to be good without treatment.

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.

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

Johns Hopkins patient information

Last revised: December 6, 2012
by Simon D. Mitin, M.D.

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