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.

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.

There are usually no symptoms.

• Prolonged partial thromboplastin time
• Abnormal factor XII assay

Treatment is generally unnecessary.

The outcome is expected to be good without treatment.

There are usually no complications.

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.