scholarly journals APC Resistance

Thrombophilia ◽  
10.5772/25495 ◽  
2011 ◽  
Author(s):  
Gerry A.F.
Keyword(s):  
Apc Resistance

The Incidence of Factor V Leiden in a Normal Irish Population and Its Relationship to the Laboratory Diagnosis of APC Resistance

1999 ◽  
Vol 81 (04) ◽  
pp. 661-663 ◽  
Author(s):  
Joseph Vaughan ◽  
Cariosa Power ◽  
Catherine Nolan ◽  
Don McCarthy ◽  
Ivan Shirley
Keyword(s):  
Factor V Leiden ◽  
Laboratory Diagnosis ◽  
Factor V ◽  
Irish Population ◽  
Apc Resistance

“Pseudo Homozygous” Activated Protein C Resistance due to Double Heterozygous Factor V Defects (Factor V Leiden Mutation and Type I Quantitative Factor V Defect) Associated with Thrombosis: Report of Two Cases Belonging to Two Unrelated Kindreds

1996 ◽  
Vol 75 (03) ◽  
pp. 422-426 ◽  
Author(s):  
Paolo Simioni ◽  
Alberta Scudeller ◽  
Paolo Radossi ◽  
Sabrina Gavasso ◽  
Bruno Girolami ◽  
...  
Keyword(s):  
Protein C ◽  
Dna Analysis ◽  
Activated Protein C ◽  
Factor V Leiden ◽  
Type I ◽  
Factor V ◽  
Factor V Leiden Mutation ◽  
Thrombotic Risk ◽  
Apc Resistance ◽  
Quantitative Factor

SummaryTwo unrelated patients belonging to two Italian kindreds with a history of thrombotic manifestations were found to have a double heterozygous defect of factor V (F. V), namely type I quantitative F. V defect and F. V Leiden mutation. Although DNA analysis confirmed the presence of a heterozygous F. V Leiden mutation, the measurement of the responsiveness of patients plasma to addition of activated protein C (APC) gave results similar to those found in homozygous defects. It has been recently reported in a preliminary form that the coinheritance of heterozygous F. V Leiden mutation and type I quantitative F. V deficiency in three individuals belonging to the same family resulted in the so-called pseudo homozygous APC resistance with APC sensitivity ratio (APC-SR) typical of homozygous F. V Leiden mutation. In this study we report two new cases of pseudo homozygous APC resistance. Both patients experienced thrombotic manifestations. It is likely that the absence of normal F. V, instead of protecting from thrombotic risk due to heterozygous F. V Leiden mutation, increased the predisposition to thrombosis since the patients became, in fact, pseudo-homozygotes for APC resistance. DNA-analysis is the only way to genotype a patient and is strongly recommended to confirm a diagnosis of homozygous F. V Leiden mutation also in patients with the lowest values of APC-SR. It is to be hoped that no patient gets a diagnosis of homozygous F. V Leiden mutation based on the APC-resi-stance test, especially when the basal clotting tests, i.e., PT and aPTT; are borderline or slightly prolonged.

Elevated Levels of Prothrombin Activation Fragment 1+2 in Plasma from Patients with Heterozygous Arg506 to Gin Mutation in the Factor V Gene (APC-Resistance) and/or Inherited Protein S Deficiency

1996 ◽  
Vol 75 (02) ◽  
pp. 270-274 ◽  
Author(s):  
Benget Zöller ◽  
Johan Holm ◽  
Peter Svensson ◽  
Björn Dahlbäck
Keyword(s):  
Plasma Concentration ◽  
Protein C ◽  
Protein S ◽  
Factor V ◽  
Protein S Deficiency ◽  
Apc Resistance ◽  
S Deficiency ◽  
Increased Risk ◽  
Factor V Gene ◽  
V Gene

SummaryInherited resistance to activated protein C (APC-resistance), caused by a point mutation in the factor V gene leading to replacement of Arg(R)506 with a Gin (Q), and inherited protein S deficiency are associated with functional impairment of the protein C anticoagulant system, yielding lifelong hypercoagulability and increased risk of thrombosis. APC-resistance is often an additional genetic risk factor in thrombosis-prone protein S deficient families. The plasma concentration of prothrombin fragment 1+2 (F1+2), which is a marker of hyper-coagulable states, was measured in 205 members of 34 thrombosis-prone families harbouring the Arg506 to Gin mutation (APC-resistance) and/or inherited protein S deficiency. The plasma concentration of F1+2 was significantly higher both in 38 individuals carrying the FV:Q506 mutation in heterozygous state (1.7 ± 0.7 nM; mean ± SD) and in 48 protein S deficient cases (1.9 ± 0.9 nM), than in 100 unaffected relatives (1.3 ±0.5 nM). Warfarin therapy decreased the F1+2 levels, even in those four patients who had combined defects (0.5 ± 0.3 nM). Our results agree with the hypothesis that individuals with APC-resistance or protein S deficiency have an imbalance between pro- and anti-coagulant forces leading to increased thrombin generation and a hypercoagulable state.

Phenotyping and Genotyping of Coagulation Factor V Leiden

1996 ◽  
Vol 75 (02) ◽  
pp. 267-269 ◽  
Author(s):  
H Engel ◽  
L Zwang ◽  
H H D M van Vliet ◽  
J J Michiles ◽  
J Stibbe ◽  
...  
Keyword(s):  
Factor V Leiden ◽  
Coagulation Factor ◽  
Diagnostic Value ◽  
Resistance Test ◽  
Amplification Refractory Mutation System ◽  
Factor V ◽  
Chain Reactions ◽  
Apc Resistance ◽  
Specificity And Sensitivity ◽  
Coagulation Factor V

SummaryThe currently used activated Protein C resistance test demonstrated to be of limited diagnostic value for the detection of the mutant Factor V Leiden. Moreover, this assay is not useful for patients under anticoagulant therapy. A modification of the APC resistance test, applying Factor V deficient plasma is described which demonstrates a specificity and sensitivity of 1.0. The superiority of the modified APC resistance test over the existing APC resistance test was verified by genotyping.For that purpose, the Amplification Refractory Mutation System (ARMS) was applied to the detection of the G to A mutation at position 1691 in the gene encoding coagulation Factor V. The mutation at that position could be easily detected by using each of two allele-specific oligonucleotide primers concomitantly with one common primer in two separate polymerase chain reactions, thereby amplifying a fragment of 186 base-pairs of the Factor V gene.

The Modified APC Resistance Test

1995 ◽  
Vol 74 (03) ◽  
pp. 995-995 ◽  
Author(s):  
K W E Denson ◽  
S V Reed ◽  
M E Haddon
Keyword(s):  
Resistance Test ◽  
Apc Resistance

Molecular Characterization of a Type I Quantitative Factor V Deficiency in a Thrombosis Patient that Is “Pseudo Homozygous” for Activated Protein C Resistance

1997 ◽  
Vol 77 (02) ◽  
pp. 252-257 ◽  
Author(s):  
Joan F Guasch ◽  
Ruud P M Lensen ◽  
Rogier M Bertina
Keyword(s):  
Protein C ◽  
Dna Analysis ◽  
Activated Protein C ◽  
Type I ◽  
Factor V ◽  
Sequencing Analysis ◽  
Apc Resistance ◽  
Quantitative Factor ◽  
Factor V Deficiency ◽  
Fv Leiden

SummaryResistance to activated protein C (APC), which is associated with the FV Leiden mutation in the large majority of the cases, is the most common genetic risk factor for thrombosis. Several laboratory tests have been developed to detect the APC-resistance phenotype. The result of the APC-resistance test (APC-sensitivity ratio, APC-SR) usually correlates well with the FV Leiden genotype, but recently some discrepancies have been reported. Some thrombosis patients that are heterozygous for FV Leiden show an APC-SR usually found only in homozygotes for the defect. Some of those patients proved to be compound heterozygotes for the FV Leiden mutation and for a type I quantitative factor V deficiency. We have investigated a thrombosis patient characterized by an APC-SR that would predict homozygosity for FV Leiden. DNA analysis showed that he was heterozygous for the mutation. Sequencing analysis of genomic DNA revealed that the patient also is heterozygous for a G5509→A substitution in exon 16 of the factor V gene. This mutation interferes with the correct splicing of intron 16 and leads to the presence of a null allele, which corresponds to the “non-FV Leiden” allele. The conjunction of these two defects in the patient apparently leads to the same phenotype as observed in homozygotes for the FV Leiden mutation.

The 20210 A Allele of the Prothrombin Gene Is a Common Risk Factor among Swedish Outpatients with Verified Deep Venous Thrombosis

1997 ◽  
Vol 78 (03) ◽  
pp. 0990-0992 ◽  
Author(s):  
Andreas Hillarp ◽  
Bengt Zӧller ◽  
Peter J Svensson ◽  
Bjӧrn Dahlbäck
Keyword(s):  
Risk Factor ◽  
Venous Thrombosis ◽  
Deep Venous Thrombosis ◽  
Odds Ratio ◽  
Untranslated Region ◽  
Control Group ◽  
Common Risk Factor ◽  
Apc Resistance ◽  
Healthy Control ◽  
Prothrombin Gene

SummaryA dimorphism in the 3’-untranslated region of the prothrombin gene (G to A transition at position 20210) has recently been reported to be associated with increases in plasma prothrombin levels and in the risk of venous thrombosis (1). We have examined the prothrombin dimorphism among 99 unselected outpatients with phlebography verified deep venous thrombosis, and in 282 healthy controls. The prevalence of the 20210 A allele was 7.1% (7/99) in the patient group, and 1.8% (5/282) in the healthy control group (p = 0.0095). The relative risk of venous thrombosis was calculated to be 4.2 (95% Cl, 1.3 to 13.6), and was still significant when adjustment was made for age, sex and the factor V:R506Q mutation causing APC resistance [odds ratio 3.8 (95% Cl, 1.1 13.2)]. As previously reported, 28% of the patients were carriers of the factor V:R506Q mutation. Thus, 34% (one patient carried both traits) of unselected patients with deep venous thrombosis were carriers of an inherited prothrombotic disorder. To sum up, our results confirm the 20210 A allele of the prothrombin gene to be an important risk factor for venous thrombosis.

Proposal for Objective Evaluation of the Performance of Various Functional APC-resistance Tests in Genotyped Patients

1997 ◽  
Vol 78 (05) ◽  
pp. 1360-1365 ◽  
Author(s):  
G Freyburger ◽  
S Javorschi ◽  
S Labrouche ◽  
P Bernard
Keyword(s):  
Protein S ◽  
Objective Evaluation ◽  
Original Method ◽  
Screening Methods ◽  
Factor Xii ◽  
Factor V ◽  
Likelihood Ratios ◽  
Modified Method ◽  
Apc Resistance ◽  
Two Parameters

SummaryThe aim of the present study was to evaluate the relative performance of five screening methods for APC resistance caused by the factor V:Q506 mutation: the original method Coatest® APC™ Resistance Chromogenix, a modified method using the same reagents but a predilution 1+4 of the plasma in a factor V deficient plasma from Stago (Stago deficient V) or from Chromogenix (V-DEF Plasma), the Coatest® APC™ Resistance V (Chromogenix), and Accelerimat™ from bioMérieux. Normalization was done against a pool of normal plasmas for the methods from Chromogenix. The study included 350 subjects, 219 were genotyped (174 FV:R506R, 42 FV:Q506R, 3 FV:Q506Q) and most of them were assessed by more than one method. Uncertainty in predicting the FV genotype was evaluated by statistical analysis, which provided a way to quantitate the performance of the different diagnostic approaches. Performance of each test was evaluated by its sensitivity, specificity, R.O.C. curves, positive and negative likelihood ratios (LR), and the overall performance was determined by two parameters derived from the LR curves : the maximum LR value obtained at the crossover of the two curves, and the distance between the two curves for LR = 10. Coatest® APC™ Resistance V and Accelerimat™ were proven to be the methods most able to discriminate for factor V:Q506, while normalization was not shown to improve the screening performance. The original method from Chromogenix was confirmed to undergo many influences (factor XII, PAI-1, thrombin- antithrombin complexes, antithrombin III, hematocrit). Although a very good improvement was provided by the newest methods, they were shown to be influenced by protein S and/or factor V levels in the sample plasma.

scholarly journals Improved Characteristics of aPC-Resistance Assay:Coatest aPC Resistance by Predilution of Samples With Factor V Deficient Plasma

1996 ◽  
Vol 106 (5) ◽  
pp. 588-593 ◽  
Author(s):  
Stylianos Kapiotis ◽  
Peter Quehenberger ◽  
Bernd Jilma ◽  
Sylvia Handler ◽  
Ingrid Pabinger-Fasching ◽  
...  
Keyword(s):  
Factor V ◽  
Apc Resistance ◽  
Improved Characteristics
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