The Factor V (Leiden) Test

Quehenberger, Peter; Handler, Sylvia; Mannhalter, Christine; Kyrle, Paul A.; Speiser, Wolfgang

doi:10.1016/s0049-3848(99)00090-0

Cited by 18 publications

(4 citation statements)

References 18 publications

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“…Sensitivity and specificity for F5 variants is improved with sample predilution in FVDP, which corrects for PC, PS, and coagulation factor deficiencies and elevations. 179,205 A different approach is taken with an assay employing the FX activator from Southern Pacific rattlesnake (Crotalus viridis helleri) venom in the presence of exogenous APC, phospholipid, and Ca 2þ . 206 Test plasma is diluted in buffer and then further diluted in FVDP, and clotting times below a reference range are designated as having APCR.…”

Section: Snake Venom-based Assaysmentioning

confidence: 99%

“…Initiation of coagulation with RVV-X, the FX activator from Russell's viper ( Daboia russelli ) venom, for the baseline clotting time, and addition of Protac to activate endogenous PC for the anticoagulated clotting time, is an alternative to CAPCR. 205 Ratios are generated identically to CAPCR and MAPCR. Bypassing the intrinsic pathway improves specificity, although it negates sensitivity to the acquired APCR of elevated FVIII, whereas high phospholipid concentration reduces LA interference, and the reagents contain a heparin neutralizer.…”

Section: Activated Protein C Resistancementioning

confidence: 99%

“…Sensitivity and specificity for F5 variants is improved with sample predilution in FVDP, which corrects for PC, PS, and coagulation factor deficiencies and elevations. 179 205…”

Section: Activated Protein C Resistancementioning

confidence: 99%

See 2 more Smart Citations

Thrombophilia Screening: Not So Straightforward

Moore

2024

Semin Thromb Hemost

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Although inherited thrombophilias are lifelong risk factors for a first thrombotic episode, progression to thrombosis is multifactorial and not all individuals with inherited thrombophilia develop thrombosis in their lifetimes. Consequently, indiscriminate screening in patients with idiopathic thrombosis is not recommended, since presence of a thrombophilia does not necessarily predict recurrence or influence management, and testing should be selective. It follows that a decision to undertake laboratory detection of thrombophilia should be aligned with a concerted effort to identify any significant abnormalities, because it will inform patient management. Deficiencies of antithrombin and protein C are rare and usually determined using phenotypic assays assessing biological activities, whereas protein S deficiency (also rare) is commonly detected with antigenic assays for the free form of protein S since available activity assays are considered to lack specificity. In each case, no single phenotypic assay is capable of detecting every deficiency, because the various mutations express different molecular characteristics, rendering thrombophilia screening repertoires employing one assay per potential deficiency, of limited effectiveness. Activated protein C resistance (APCR) is more common than discrete deficiencies of antithrombin, protein C, and protein S and also often detected initially with phenotypic assays; however, some centres perform only genetic analysis for factor V Leiden, as this is responsible for most cases of hereditary APCR, accepting that acquired APCR and rare F5 mutations conferring APCR will go undetected if only factor V Leiden is evaluated. All phenotypic assays have interferences and limitations, which must be factored into decisions about if, and when, to test, and be given consideration in the laboratory during assay performance and interpretation. This review looks in detail at performance and limitations of routine phenotypic thrombophilia assays.

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Section: Snake Venom-based Assaysmentioning

confidence: 99%

Section: Activated Protein C Resistancementioning

confidence: 99%

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Thrombophilia Screening: Not So Straightforward

Moore

2024

Semin Thromb Hemost

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“…Direct FX activation improves specificity since the intrinsic pathway is bypassed, concentrated phospholipid reduces LA interference, and reagents contain a heparin neutralizer. Predilution of plasma in FVDP further improves specificity for hereditary APC-R. 133 The FX activator from Southern Pacific rattlesnake ( Crotalus viridis helleri ) venom is employed in another assay to initiate coagulation in buffer-diluted test plasma further diluted in FVDP, in the presence of phospholipid, exogenous APC, and Ca 2+ ( Fig. 2B ).…”

Section: Thrombophilia Screeningmentioning

confidence: 99%

Snake Venoms in Diagnostic Hemostasis and Thrombosis

Moore

2021

Semin Thromb Hemost

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Snake venoms have evolved primarily to immobilize and kill prey, and consequently, they contain some of the most potent natural toxins. Part of that armory is a range of hemotoxic components that affect every area of hemostasis, which we have harnessed to great effect in the study and diagnosis of hemostatic disorders. The most widely used are those that affect coagulation, such as thrombin-like enzymes unaffected by heparin and direct thrombin inhibitors, which can help confirm or dispute their presence in plasma. The liquid gold of coagulation activators is Russell's viper venom, since it contains activators of factor X and factor V. It is used in a range of clotting-based assays, such as assessment of factor X and factor V deficiencies, protein C and protein S deficiencies, activated protein C resistance, and probably the most important test for lupus anticoagulants, the dilute Russell's viper venom time. Activators of prothrombin, such as oscutarin C from Coastal Taipan venom and ecarin from saw-scaled viper venom, are employed in prothrombin activity assays and lupus anticoagulant detection, and ecarin has a valuable role in quantitative assays of direct thrombin inhibitors. Snake venoms affecting primary hemostasis include botrocetin from the jararaca, which can be used to assay von Willebrand factor activity, and convulxin from the cascavel, which can be used to detect deficiency of the platelet collagen receptor, glycoprotein VI. This article takes the reader to every area of the diagnostic hemostasis laboratory to appreciate the myriad applications of snake venoms available in diagnostic practice.

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Activated protein C resistance testing for factor V Leiden

2014

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Activated protein C resistance assays can detect factor V Leiden with high accuracy, depending on the method used. Factor Xa inhibitors such as rivaroxaban and direct thrombin inhibitors including dabigatran, argatroban, and bivalirudin can cause falsely normal results. Lupus anticoagulants can cause incorrect results in most current assays. Assays that include dilution into factor V-deficient plasma are needed to avoid interference from factor deficiencies or elevations, which can arise from a wide variety of conditions such as warfarin, liver dysfunction, or pregnancy. The pros and cons of the currently available assays are discussed.

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The Factor V (Leiden) Test

Cited by 18 publications

References 18 publications

Thrombophilia Screening: Not So Straightforward

Thrombophilia Screening: Not So Straightforward

Snake Venoms in Diagnostic Hemostasis and Thrombosis

Activated protein C resistance testing for factor V Leiden

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