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Factor XII deficiency is an inherited disorder that affects a protein (factor XII) involved in blood clotting.
When you bleed, the body a series of reactions takes place to help the blood clot. This is called the coagulation cascade. Factor XII is a special protein, called a coagulation factor, which helps in this process.
Each factor in the process triggers the next reaction. The final product is the blood clot. There is a higher chance of excess bleeding when one or more of these clotting factors are missing.
A lack of factor XII does not cause you to bleed abnormally. However, the blood takes longer than normal to clot in a test tube.
Factor XII deficiency is a rare inherited disorder.
There are usually no symptoms.
Factor XII deficiency is most often found when clotting tests are done for routine screening.
Tests may include:
Treatment is usually not needed.
The outcome is expected to be good without treatment.
There are usually no complications.
The health care provider usually discovers this condition when running other lab tests.
This is an inherited disorder. There is no known way to prevent it.
Gailani D, Neff AT. Rare coagulation factor deficiencies. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Saunders Elsevier; 2012:chap 139.
Kessler C. Hemorrhagic disorders: Coagulation factor deficiencies. In: Goldman L, Ausiello D, eds. Goldman's Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007:chap 180.