Activated Protein C Resistance

An inherited (autosomal dominant) or acquired defect in the anticoagulant response to activated protein C, resulting in an increased risk of thrombosis.
Clinical findings Increased risk of deep vein thrombosis (DVT), venous thrombosis; it is responsible for 20% to 50% of DVT.
Pathogenesis Protein C, a key regulator of coagulation, circulates in an inactivated form and is activated by the binding of thrombin to thrombomodulin receptors on vascular endothelial cells; once activated, protein C lyses coagulation factors Va and VIIIa. Activated protein C resistance is caused by a failure of protein C to cleave Factor Va and/or Factor VIIIa.

APC resistance

Activated protein C resistance, see there.

APC resistance

Abbrev. for activated protein C resistance, an abnormal tendency to blood clotting caused by a mutation in the gene for blood clotting factor V. This mutation is known as the FACTOR V LEIDEN MUTATION. APC resistance is the commonest cause of inherited THROMBOPHILIA.

Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

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References in periodicals archive

It included an aPTT-based APCR assay with dilution in factor V-deficient plasma (Coatest APC Resistance V assay, Chromogenix), on a Star Evolution analyzer, and an FVL DNA assay (Invader assay, Hologic, Boston, Massachusetts).

Rivaroxaban Causes Missed Diagnosis of Protein S Deficiency but Not of Activated Protein C Resistance (Factor V Leiden)

Prothrombotic workups including protein C activity, protein S activity, antithrombin III level, APC resistance, lupus anticoagulant, anticardiolipin antibodies, factor VIII inhibitor screening, and factor V Leiden defect were all negative, except for heterozygous mutation for prothrombin G20210A; the d-dimer level was normal 0.14 mcg/mL (0-0.5) and coagulation tests revealed low FVIII levels.

Upper Limb Deep Vein Thrombosis in Patient with Hemophilia A and Heterozygosity for Prothrombin G20210A: A Case Report and Review of the Literature

APC resistance and third generation contraceptives.

Family planning in south Africa: missing essentials and desirables

APC resistance is a common risk factor for thrombosis, and between 20% and 60% of thrombophilic patients suffer from some form of APC resistance.

A 52-year-old man with ecchymotic leg ulcers

determined the prevalence of APC resistance in 100 patients [39].

Association between thrombophilia and the post-thrombotic syndrome

All assessments were reported to be within normal physiological limits except for the APC resistance assay, which was reported low at 0.7 (normal 2.0-4.0 L).

Case of ischemic colitis in a young adolescent associated with triphasic hormonal contraceptive therapy: a case report and review of the literature

"Our excellent HemosIL and Chromogenix reagent product line offers a broad spectrum of diagnostic tests, including assays for the detection of APC resistance and factor V Leiden mutations.

Instrumentation Laboratory wins patent infringement and unfair competition trial against Diagnostica Stago relating to reagents for hemostasis

(16) Tests ordered should include Factor V Leiden (APC resistance), protein S deficiency, protein C deficiency, antithrombin as say, Prothrombin G20210A mutation, factor VIII activity, homocysteine level, and Lupus anticoagulant.

Factor V Leiden: an overview

This finding is in agreement with the fact that patients with the FV-Leiden mutation show APC resistance.

Utility of thrombin-generation assay in the screening of factor V G1691A (Leiden) and prothrombin G20210A mutations and protein S deficiency

* APC Resistance (functional test for Factor V Leiden)

Testing for genetic predisposition to venous thrombosis

(24) reported that the presence of LA was significantly associated with acquired APC resistance (APC-R) in patients with SLE.

Acquired activated protein C resistance associated with IgG antibodies against [[beta].sub.2]-glycoprotein I and prothrombin as a strong risk factor for venous thromboembolism

Low levels of protein S activity in factor V depleted plasma used in APC resistance test.

Activated protein C resistance, the factor V Leiden mutation, and a laboratory testing algorithm. (Original Articles)