antithrombin III

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antithrombin

 [an″te-throm´bin]
any naturally occurring or therapeutically administered substance that neutralizes the action of thrombin and thus limits or restricts blood coagulation.
antithrombin I fibrin, referring to the capacity of fibrin to adsorb thrombin and thus neutralize it.
antithrombin III a naturally occurring inhibitor of blood coagulation; it is an α2-globulin member of the serpin group, synthesized in the liver and found in the plasma and various extravascular sites. It inactivates thrombin as well as certain coagulation factors and kallikrein. Inherited deficiency of the protein, an autosomal dominant disorder, is associated with recurrent deep vein thrombosis and pulmonary emboli. Complications from the disorder are prevented and, in conjunction with heparin, treated with a preparation of antithrombin III from pooled human plasma, administered intravenously.

an·ti·throm·bin III

a plasma α2-globulin process that inhibits thrombin and has anticoagulant activities. Deficiency [MIM*107300] is commonly inherited as an autosomal dominant trait, caused by mutation in antithrombin III gene (AT3) or chromosome 1q; this is one of the few known mendelizing disorders from which thrombotic disease occurs.

SERPINC1

A gene on chromosome 1q23-q25.1 that encodes antithrombin III, a member of the serine protease inhibitor (serpin) family that rapidly inhibits thrombin, as well as other activated serine proteases of the coagulation system, and regulates the coagulation cascade.

Molecular pathology
SERPINC1 mutations cause antithrombin-III deficiency.

antithrombin III

Hematology A 58 kD α2-glycoprotein with a single polypeptide chain that inactivates serine proteases–thrombin and other coagulation proteins including factor Xa, IXa, kallikrein and others by an irreversible heparin-dependent reaction Function AT III dissolves blood clots that normally form within the circulation; heparin's anticoagulant activity hinges on activation of AT-III; AT-III-deficient individuals do not benefit from heparin therapy; ↓ AT-III may be a congenital AD condition, or acquired, occurring in DIC–due to 'consumption' or in liver disease–due to ↓ AT-III production, resulting in an ↑ risk of coagulation; AT III is ↓ in congenital deficiency, liver transplant, DIC, nephrotic syndrome, cirrhosis, chonic liver disease, carcinoma, mid-menstrual cycle; AT III is defective in 0.14% to 0.5% of the general population. See Hereditary thrombophilia, Recombinant human antithrombin III.
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