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

SummaryThe APC-resistance test consists of two APTT’s, one in the presence and one in the absence of a fixed amount of Activated Protein C (APC), and is a simple and reliable method to detect a reduced sensitivity to the anticoagulant action of APC (APC-resistance). At a fixed concentration of APC the prolongation of the APTT is dependent on the activator, the CaCl2 concentration, the citrate concentration in the sample, and on sample handling. The effect of sample handling can be reduced by calculating the APC-Sensitivity Ratio (APC-SR). The actual prolongation of the APTT is also influenced by low protein S levels (reduction of APC-SR) and by reduced levels of factors V, VIII and IX (increase of APC-SR). The APC-SR is most dramaticly effected by reduced levels of factors II and X, which result often in “unmeasurable” APC-SR’s in plasmas of patients on oral anticoagulant treatment. So at present no reliable APC-SR’s can be measured in these patients. Patients treated with heparin can be tested after treatment of their plasma with Hepzym®. The inter- and intra-assay variation in the APC-SR is 4% and 2%, respectively, when using the same batches of activator and APC. The variation which is introduced in the APC-SR by use of different batches of activator or APC, or by the use of different APC or CaCl2 concentrations, can effectively be avoided by expressing the result of the test in normalized-APC-SR (n-APC-SR).The diagnosis of APC-resistance is defined by a n-APC-SR < 0.84. Patients who are heterozygous for the Factor V Leiden mutation have a n-APC-SR of 0.45-0.70, while patients who are homozygous for the mutation have a n-APC-SR <0.45.

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“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

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650290 ◽

1996 ◽

Vol 75 (03) ◽

pp. 422-426 ◽

Cited By ~ 53

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.

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Phenotyping and Genotyping of Coagulation Factor V Leiden

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650258 ◽

1996 ◽

Vol 75 (02) ◽

pp. 267-269 ◽

Cited By ~ 27

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.

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The Diagnosis and Clinical Manifestations of Activated Protein C Resistance: A Case Report and Review of the Literature

Vascular Medicine ◽

10.1177/1358863x9600100406 ◽

1996 ◽

Vol 1 (4) ◽

pp. 275-280 ◽

Cited By ~ 5

Author(s):

Howard Daniel Hoerl ◽

Aldo Tabares ◽

Kandice Kottke-Marchant

Keyword(s):

Case Report ◽

Protein C ◽

Activated Protein C ◽

Clinical Manifestations ◽

Factor V Leiden ◽

Laboratory Diagnosis ◽

Factor V ◽

Review Of The Literature ◽

Activated Protein C Resistance ◽

Genetic Anomaly

Activated protein C resistance (APCR) is a recently discovered, medically important cause of venous thrombosis. More than 95% of cases are due to factor V Leiden (FVL), a mutated form of factor V that is resistant to degradation by activated protein C. The prevalence of this disorder, which is inherited in an autosomal dominant fashion, is approximately 5% among asymptomatic people of European heritage. In addition, 20 to 60% of patient cohorts with previous thrombosis demonstrate APCR, making it the most common known genetic cause of abnormal thrombophilia. Current laboratory techniques available for diagnosis include functional assays, such as the APC ratio, as well as DNA-based tests that detect the specific genetic anomaly responsible for FVL. A case report is presented, along with a review of the literature highlighting epidemiology, pathogenesis, clinical features and methods for laboratory diagnosis.

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APC-resistance as a possible predictor of recurrent thrombosis in women with Factor V Leiden

Journal of obstetrics and women s diseases ◽

10.17816/jowd67650-59 ◽

2018 ◽

Vol 67 (6) ◽

pp. 50-59 ◽

Cited By ~ 1

Author(s):

Maria G. Nikolayeva ◽

Andrey P. Momot ◽

Marina S. Zaynulina ◽

Ksenia A. Momot ◽

Natalia N. Yasafova

Keyword(s):

Thrombotic Event ◽

Activated Protein C ◽

Factor V Leiden ◽

Resistance Index ◽

Reproductive Age ◽

Control Group ◽

Factor V ◽

Recurrent Thrombosis ◽

Apc Resistance ◽

Venous Thromboembolic

Hypothesis/aims of study. The current analysis was undertaken to elucidate the role of Factor Va resistance to proteolytic cleavage by activated protein C in FVL(1691)GA female carriers in the development of acute and recurrent thromboses. Study design, materials and methods. A prospective clinical cohort study of 1100 women of reproductive age was conducted, with the course and outcomes of 2,707 pregnancies analyzed. Two cohorts were specified: the main group consisted of 500 patients with FV(1691)GA genotype, and the control group consisted of 600 patients with FVL(1691)GG genotype. Results. FVL(1691)GA genotype was significantly associated with the development of venous thromboembolic complications (VTEC) compared to FVL(1691)GG genotype (OR 9.3; p < 0.0001). Episodes of recurrent thrombosis during and outside of pregnancy were registered only in FVL(1691)GA patients (OR 5.7, p = 0.2). In all cases, at the time of the thrombotic event and during the period before the episode of acute or recurrent thrombosis, an APC resistance normalized ratio (NR) value was ≤ 0.49, with no episodes of VTEC registered with an APC resistance NR value ≥ 0.5. Conclusion. Venous thromboses occur under the condition of expressed APC resistance with underlying FVL(1691)GA carriage. The APC resistance index can serve as an objective biochemical marker to determine the feasibility of thromboprophylaxis within the framework of personalized medicine.

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APC-RESISTANCE ASSOCIATED WITH FACTOR V LEIDEN GENE MUTATION (GENOTYPE GA): CLINICAL OCCURRENCE IN PREGNANCY

Тромбоз, гемостаз и реология ◽

10.25555/thr.2018.1.0823 ◽

2018 ◽

Author(s):

М.Г. Николаева ◽

А.П. Момот ◽

Г.В. Сердюк ◽

В.А. Елыкомов ◽

К.А. Момот ◽

...

Keyword(s):

Pregnant Women ◽

Gene Mutation ◽

Activated Protein C ◽

Factor V Leiden ◽

Control Group ◽

Factor V ◽

Factor V Leiden Mutation ◽

Apc Resistance ◽

Factor Va ◽

And Control

Цель исследования: изучить связь феномена резистентности фактора Vа к активированному протеину С (АПС-резистентность) при носительстве мутации гена FVL (1691) GA с клинической реализацией во время беременности тромботических событий и гестационных осложнений, таких как преэклампсия, задержка развития плода и невынашивание беременности. Материалы и методы. Проведено проспективное клиническое когортное исследование 1100 беременных. Выделено 2 когорты: основная группа – 500 пациенток с генотипом FVL (1691) GA и группа контроля – 600 женщин с генотипом FVL (1691) GG. Результаты. Медиана нормализованного отношения (НО) АПС-резистентности в контрольной группе у беременных с генотипом FVL (1691) GG колебалась в диапазоне 1,0→0,86. У беременных – носителей генотипа FVL (1691) GA этот показатель был достоверно ниже – 0,55→0,48 (р < 0,05). У пациенток при НО > 0,5 течение беременности было благоприятным. Более выраженная АПС-резистентность (НО ≤ 0,49) ассоциировалась с гестационными осложнениями. Заключение. Полученные данные по АПС-резистентности позволяют относить в группу высокого риска по тромботическим и акушерским осложнениям женщин – носительниц мутации фактора V Лейден (1691) не только с генотипом АА, но и с генотипом GA. AПС-резистентность ≤ 0,49 (по показателю НО) при носительстве мутации фактора V Лейден (1691) GA может рассматриваться как прогностический маркер развития гестационных осложнений с наибольшей точностью при сроке 7-8 недель беременности. Aim: to study during pregnancy the relationship between factor Va resistance to activated protein C (APC-resistance) in carriers of FVL gene mutation (1691) GA with clinical realization of thrombotic events and gestational complications such as preeclampsia, fetal growth retardation and miscarriage. Materials and methods. A prospective clinical cohort study of 1100 pregnant women was performed. Two cohorts were identified: main group – 500 patients with FVL genotype (1691) GA and control group – 600 women with FVL genotype (1691) GG. Results. The median of normalized ratio (NR) of APC resistance in the control group with FVL genotype (1691) GG ranged from 1.0→0.86. In pregnant women – the carriers of FVL genotype (1691) GA this parameter was significantly lower – 0.55→0.48 (р < 0.05). In patients with HO > 0.5 the course of pregnancy was favorable. More expressed APS-resistance (НО ≤ 0,49) was associated with gestational complications. Conclusion. The obtained data on APC-resistance allow to classify women – the carriers of Factor V Leiden (1691) mutation, not only with the AA genotype but also with GA genotype as the group of high risk for thrombotic and obstetric complications. APC resistance ≤ 0.49 (according NR) with the carriage of Factor V Leiden mutation (1691) GA can be considered as a prognostic marker for the development of gestational complications with the greatest accuracy at a period of 7-8 weeks of gestation.

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Is APC Resistance a Risk Factor for Venous Thromboembolism in Patients over 70 Years?

Thrombosis and Haemostasis ◽

10.1055/s-0037-1613260 ◽

2002 ◽

Vol 88 (10) ◽

pp. 587-591 ◽

Cited By ~ 8

Author(s):

Karine Lacut ◽

Grégoire Le Gal ◽

Patrick Van Dreden ◽

Luc Bressollette ◽

Pierre-Yves Scarabin ◽

...

Keyword(s):

Risk Factor ◽

Venous Thromboembolism ◽

Odds Ratio ◽

Dna Analysis ◽

Activated Protein C ◽

Factor V Leiden ◽

Factor V ◽

Apc Resistance ◽

Increased Risk ◽

History Of

SummaryActivated protein C (APC) resistance is the most common risk factor for venous thromboembolism (VTE). Previous studies mostly analysed patients under 70 years and reported a four-to sevenfold increased risk. This case-control study included consecutive patients referred for a clinical suspicion VTE to our medical unit: 621 patients with a well-documented diagnosis (cases) and 406 patients for which the diagnosis was ruled out and who had no personal history of VTE (controls). APC resistance related to factor V Leiden was defined by either a positive DNA analysis or a positive STA® Staclot APC-R assay. Under 70 years, APC resistance was associated with a threefold increased risk of VTE (odds ratio 3.2, 95% CI, 1.7 to 6.0), whereas in patients over 70 years, it appeared to be no longer a strong risk factor (odds ratio 0.8, 95% CI, 0.4 to 1.7). Age appeared as an effectmeasure modifier with a significant interaction (p = 0.005). Our data suggest that APC resistance is not a risk factor for VTE in elderly.

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Factor V Cambridge: A New Mutation (Arg306→Thr) Associated With Resistance to Activated Protein C

Blood ◽

10.1182/blood.v91.4.1140 ◽

1998 ◽

Vol 91 (4) ◽

pp. 1140-1144 ◽

Cited By ~ 165

Author(s):

David Williamson ◽

Karen Brown ◽

Roger Luddington ◽

Caroline Baglin ◽

Trevor Baglin

Keyword(s):

Venous Thrombosis ◽

Cleavage Site ◽

Protein C ◽

Activated Protein C ◽

Factor V Leiden ◽

Factor V ◽

Degree Relative ◽

Prothrombinase Complex ◽

Apc Resistance ◽

The Common

AbstractA new factor V mutation associated with resistance to activated protein C and thrombosis (factor V Cambridge, Arg306→Thr) was found in one patient from a carefully selected group of 17 patients with venous thrombosis and confirmed APC resistance in the absence of the common Gln506 mutation. The Arg306 mutation was also present in a first degree relative who also had APC resistance. Other potential causes of APC resistance, such as a mutation at the Arg679 site and the factor V HR2 haplotype, were excluded. Subsequent screening of 585 patients with venous thromboembolism and 226 blood donors did not show any other individual with this mutation. Factor VThr306 is the first description of a mutation affecting the Arg306 APC cleavage site and is the only mutation, other than factor V Leiden (Arg506→Gln), that has been found in association with APC resistance. This finding confirms the physiologic importance of the Arg306 APC-cleavage site in the regulation of the prothrombinase complex. It also supports the concept that APC resistance and venous thrombosis can result from a variety of genetic mutations affecting critical sites in the factor V cofactor.

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