[Hereditary Resistance to Activated Protein C, Factor V Leiden Mutation] Funded by the NIH • Developed at the University of Washington, Seattle

Journal of Neurology, Neurosurgery, and Psychiatry 2005;76:1331

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.

Archives of Pathology and Laboratory Medicine: Vol. 131, No. 6, pp. 866–871.

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Protein C deficiency, a deficiency of the anticoagulant protein C, is associated with a variably increased risk of thrombosis. In the rare inherited homozygous or compound heterozygous state, protein C deficiency is associated with severe life-threatening neonatal purpura fulminans or massive venous thrombosis. The inherited heterozygous state of protein C deficiency most frequently is associated with deep venous thrombosis of the lower limb but also may manifest in other venous locations. A significant percentage of patients with protein C deficiency remain asymptomatic. A family history is essential in assessing the association of a patient's deficiency with the patient's risk of thrombotic disease. Acquired protein C deficiency occurs in certain clinical scenarios, but this most often is associated with a transient predisposing factor. Last Updated: June 30, 2006

Antithrombin-III deficiency can cause or lead to thrombosis, a clot forming in a blood vessel. If a clot attached to a blood vessel wall breaks loose and travels in the bloodstream, it is called an embolus. An embolus that reaches a blood vessel in the lungs is called a pulmonary embolism. This type of clot can block the blood vessel, cut off the oxygen supply to the lung tissue, and, in some cases, cause death. Article Reviewed: 1999-03-17

Factor V Leiden thrombophilia is an inherited disorder of blood clotting. Factor V Leiden is the name of a specific mutation that results in thrombophilia, or an increased tendency to form abnormal blood clots in blood vessels. People who have the factor V Leiden mutation are at somewhat higher than average risk for a type of clot that forms in veins, such as the deep veins of the legs (deep venous thrombosis), or a clot that travels through the bloodstream and lodges in the lungs (pulmonary embolism).

These inherited disorders of blood coagulation are caused by deficiency of the Vitamin K-dependent plasma proteins C or S that are naturally occurring anticoagulants. The disorder results in an increased tendency for intravascular blood clot formation. Update Date: 4/15/2005 Updated by: Rita Nanda, MD, Department of Medicine, Section of Hematology/Oncology, University of Chicago Medical Center, Chicago, IL. Review provided by VeriMed Healthcare Network.

Circulation 2003; 107:e94-97. (c) 2003 American Heart Association, Inc.

PEDIATRICS Vol. 99 No. 6 June 1997, p. e11 Copyright ©1997 by the American Academy of Pediatrics