Chromogenix Coatest® APC™ Resistance is an APTT-based assay kit for the detection of the APC resistance phenotype, i.e. the poor anticoagulant response to activated protein C (APC). The test result (APC ratio) gives an estimation of the anticoagulant function in vivo and provides information on the thrombotic risk associated with inherited and acquired APC resistance. Detects the APC resistance phenotype regardless of its cause. Detects both inherited and acquired APC resistance.
Plasma is incubated with the APTT reagent for a standard period of time. Coagulation is initiated by the addition of CaCl2 in the absence and presence of APC and the time for clot formation is recorded.
Activated Protein C (APC) is a regulator of the coagulation cascade, by specifically inactivating factors Va and VIIIa, in the presence of phospholipids and calcium. In most of the cases (more than 90%), Activated Protein C Resistance (APCR) phenotype is caused by a Factor V gene mutation.
Activated Protein C Resistance is tested by using a clotting method performed with or without Activated Protein C. Chromogenix Coatest® APC™ Resistance, which does not involve pre-dilution with FV-deficient plasma, detects the APC resistance phenotype regardless of its cause ( inherited and acquired APC resistance).
Activated protein C (APC) is a key anticoagulant enzyme needed for the proper down-regulation of blood coagulation. A poor anticoagulant response to APC, denoted APC resistance, is a recently described blood defect found to be a major risk factor for venous thromboembolism in Western societies. At least 90% of cases with the APC resistance phenotype can be explained by a point mutation in the coagulation factor V gene, changing arginine 506 in the factor V molecule to glutamine. After activation, mutated factor V (denoted FV:Q506 or Factor V Leiden) is partially resistant to inactivation by APC, which allows for longer duration of thrombin generation and may lead to a hypercoagulable state. APC resistance due to the presence of the FV:Q506 allele is inherited as an autosomal dominant trait and has a prevalence of 2-13% in the general population. Frequencies of APC resistance among patients with venous thrombosis, depending on the selection criteria, range from 20-60%. The high prevalence of APC resistance, combined with the availability of simple blood tests by which it is detected, raises the question of whether general screening for APC resistance should be performed in conjunction with circumstantial risk factors for thrombosis such as surgery, pregnancy and oral contraceptives. Read more…