High risk of thrombosis in patients homozygous for factor V Leiden (activated protein C resistance) [see comments]

Resistance to activated protein C (APC) is a common inherited risk factor for venous thrombosis, which is associated with a mutation in coagulation factor V (factor V Leiden). We investigated the risk of venous thrombosis in individuals homozygous for this abnormality. We determined the factor V Leiden genotype in 471 consecutive patients aged less than 70 years with a first objectively confirmed deep-vein thrombosis and in 474 healthy controls. We found 85 heterozygous and seven homozygous individuals among the cases with thrombosis and 14 heterozygous individuals among the control subjects. The expected number of homozygous individuals among the controls was calculated from Hardy-Weinberg equilibrium and estimated at 0.107 (allele frequency, 1.5%). Whereas the relative risk was increased sevenfold for heterozygous individuals, it was increased 80-fold for homozygous individuals. These patients experienced their thrombosis at a much younger age (31 v 44 years). The homozygous individuals were predominantly women, most likely due to the effect of oral contraceptives. Because of the increased risk of thrombosis with age, the absolute risk becomes most pronounced in older patients, both for heterozygous and homozygous individuals. For the homozygous individuals, the absolute risk may become several percentage points per year. This implies that most individuals homozygous for factor V Leiden will experience at least one thrombotic event in their lifetime.

Download Full-text

A Reduced Sensitivity for Activated Protein C in the Absence of Factor V Leiden Increases the Risk of Venous Thrombosis

Blood ◽

10.1182/blood.v93.4.1271 ◽

1999 ◽

Vol 93 (4) ◽

pp. 1271-1276 ◽

Cited By ~ 202

Author(s):

Marieke C.H. de Visser ◽

Frits R. Rosendaal ◽

Rogier M. Bertina

Keyword(s):

Risk Factor ◽

Confidence Interval ◽

Venous Thrombosis ◽

Protein C ◽

Activated Protein C ◽

Factor V Leiden ◽

Factor V ◽

Factor V Leiden Mutation ◽

Apc Resistance ◽

Increased Risk

Abstract Activated protein C (APC) resistance caused by the factor V Leiden mutation is associated with an increased risk of venous thrombosis. We investigated whether a reduced response to APC, not due to the factor V point mutation, is also a risk factor for venous thrombosis. For this analysis, we used the Leiden Thrombophilia Study (LETS), a case-control study for venous thrombosis including 474 patients with a first deep-vein thrombosis and 474 age- and sex-matched controls. All carriers of the factor V Leiden mutation were excluded. A dose-response relationship was observed between the sensitivity for APC and the risk of thrombosis: the lower the normalized APC sensitivity ratio, the higher the associated risk. The risk for the lowest quartile of normalized APC-SR (<0.92), which included 16.5% of the healthy controls, compared with the highest quartile (normalized APC-SR > 1.05) was greater than fourfold increased (OR = 4.4; 95% confidence interval, 2.9 to 6.6). We adjusted for VIII:C levels, which appeared to affect our APC resistance test. The adjusted (age, sex, FVIII:C) odds ratio for the lowest quartile was 2.5 (95% confidence interval, 1.5 to 4.2). So, after adjustment for factor VIII levels, a reduced response to APC remained a risk factor. Our results show that a reduced sensitivity for APC, not caused by the factor V Leiden mutation, is a risk factor for venous thrombosis.

Download Full-text

The HR2 Haplotype of Factor V: Effects on Factor V Levels, Normalized Activated Protein C Sensitivity Ratios and the Risk of Venous Thrombosis

Thrombosis and Haemostasis ◽

10.1055/s-0037-1613866 ◽

2000 ◽

Vol 83 (04) ◽

pp. 577-582 ◽

Cited By ~ 48

Author(s):

Joan Guasch ◽

Pieter Kamphuisen ◽

Hans Vos ◽

Frits Rosendaal ◽

Rogier Bertina ◽

...

Keyword(s):

Venous Thrombosis ◽

Protein C ◽

Activated Protein C ◽

Factor V Leiden ◽

Compound Heterozygous ◽

Factor V ◽

Vein Thrombosis ◽

Increased Risk ◽

V Antigen ◽

Deep Vein

SummaryWe studied the HR2 haplotype of the factor V gene in a case-control study for venous thrombosis including 474 patients with a first deep-vein thrombosis and 474 age- and sex-matched healthy controls (Leiden Thrombophilia Study, LETS). We investigated both the original His1299Arg (A4070G) polymorphism and the Met385Thr (T1328C) polymorphism. This latter polymorphism, located in exon 8 (heavy chain), is always present in the HR2 haplotype, but also occurs on its own in a His1299 (wt) background. The HR2 haplotype was not associated with an increased risk of venous thrombosis (OR = 1.2, 95% confidence interval: 0.8-2.0). We did not find an association between the HR2 haplotype and a reduced sensitivity for activated protein C (APC) in non-carriers of factor V Leiden (FVL). However, in compound heterozygous FVL/HR2 carriers the sensitivity for APC was reduced. The HR2 haplotype was also associated with reduced factor V antigen levels in both patients and controls. Sequence analysis of the promoter region of factor V in HR2 homozygotes did not reveal any sequence variations that could explain the reduced FV levels. Our results show that the HR2 haplotype is not associated with an increased risk of venous thrombosis or with a reduced sensitivity for APC in non-FVL carriers. However, the HR2 haplotype is associated with a reduced sensitivity for APC in carriers of FVL and with reduced factor V antigen levels.

Download Full-text

A Reduced Sensitivity for Activated Protein C in the Absence of Factor V Leiden Increases the Risk of Venous Thrombosis

Blood ◽

10.1182/blood.v93.4.1271.404k22_1271_1276 ◽

1999 ◽

Vol 93 (4) ◽

pp. 1271-1276 ◽

Cited By ~ 1

Author(s):

Marieke C.H. de Visser ◽

Frits R. Rosendaal ◽

Rogier M. Bertina

Keyword(s):

Risk Factor ◽

Confidence Interval ◽

Venous Thrombosis ◽

Protein C ◽

Activated Protein C ◽

Factor V Leiden ◽

Factor V ◽

Factor V Leiden Mutation ◽

Apc Resistance ◽

Increased Risk

Activated protein C (APC) resistance caused by the factor V Leiden mutation is associated with an increased risk of venous thrombosis. We investigated whether a reduced response to APC, not due to the factor V point mutation, is also a risk factor for venous thrombosis. For this analysis, we used the Leiden Thrombophilia Study (LETS), a case-control study for venous thrombosis including 474 patients with a first deep-vein thrombosis and 474 age- and sex-matched controls. All carriers of the factor V Leiden mutation were excluded. A dose-response relationship was observed between the sensitivity for APC and the risk of thrombosis: the lower the normalized APC sensitivity ratio, the higher the associated risk. The risk for the lowest quartile of normalized APC-SR (<0.92), which included 16.5% of the healthy controls, compared with the highest quartile (normalized APC-SR > 1.05) was greater than fourfold increased (OR = 4.4; 95% confidence interval, 2.9 to 6.6). We adjusted for VIII:C levels, which appeared to affect our APC resistance test. The adjusted (age, sex, FVIII:C) odds ratio for the lowest quartile was 2.5 (95% confidence interval, 1.5 to 4.2). So, after adjustment for factor VIII levels, a reduced response to APC remained a risk factor. Our results show that a reduced sensitivity for APC, not caused by the factor V Leiden mutation, is a risk factor for venous thrombosis.

Download Full-text

Comparison of three activated protein C resistance tests in the risk assessment of venous thrombosis in non-carriers of the factor V Leiden mutation

Thrombosis and Haemostasis ◽

10.1160/th05-08-0593 ◽

2006 ◽

Vol 95 (04) ◽

pp. 728-734 ◽

Cited By ~ 2

Author(s):

Felipe Guerrero ◽

Catherine Arnaud ◽

Francoise Nguyen ◽

Bernard Boneu ◽

Pierre Sié

Keyword(s):

Venous Thrombosis ◽

Protein C ◽

Activated Protein C ◽

Significant Risk ◽

Factor V Leiden ◽

Factor V ◽

Activated Protein C Resistance ◽

Factor V Leiden Mutation ◽

Risk Increase ◽

Increased Risk

SummaryActivated protein C resistance (APCR), measured using the original assay described by Dahlbäck, is a risk factor for venous thrombosis independent of the factor V Leiden (FVL) mutation. This assay is based on the activated partial thromboplastin time (APTT) after plasma exposure to activated protein C (APC).As this assay was sensitive to numerous interferences, new assays have been developed for FVL screening. The objectives of the study were to investigate the association of second generation assays for APCR with venous thrombosis in FVL non-carriers. One hundred ninety-seven subjects with a history of venous thrombosis and 211 controls were explored using 3 APCR assays, the original APTT-based assay (test A), an APTT-based assay with factorV depleted plasma pre-dilution (test B) and a direct factorX activation-based assay with the same pre-dilution (test C).We found that subjects with results in the lowest quartile of the APTT-based assays are at increased risk, compared to those in the highest quartile (test A Odds Ratio = 6.39; 95%CI 3.23–12.63; test B OR=2.72; 95%CI 1.50–4.94). There was no significant risk increase associated with test C results. After adjusting for FVIII levels, the ORs of tests A and B were similar (test A OR=3.22; 95%CI 1.47–7.08; test B OR=3.10; 95%CI 1.54–6.21). In conclusion, APTT-based assays, but not direct factor X activation-based assays, effectively detect the risk for venous thrombosis independent of FVL. Pre-dilution in factor V depleted plasma is an effective way to directly assess the risk independent of FVIII levels.

Download Full-text

Coagulation Factor V Leiden Mutation Was Detected in the Patients with Activated Protein C Resistance in Thailand

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615201 ◽

1998 ◽

Vol 80 (08) ◽

pp. 344-345 ◽

Cited By ~ 2

Author(s):

Pasra Arnutti ◽

Motofumi Hiyoshi ◽

Wichai Prayoonwiwat ◽

Oytip Nathalang ◽

Chamaiporn Suwanasophon ◽

...

Keyword(s):

Protein C ◽

Activated Protein C ◽

Factor V Leiden ◽

Coagulation Factor ◽

Factor V ◽

Activated Protein C Resistance ◽

Factor V Leiden Mutation ◽

Coagulation Factor V

Download Full-text

Resistance to Activated Protein C and Factor V Leiden as Risk Factors for Venous Thrombosis

Thrombosis and Haemostasis ◽

10.1055/s-0038-1642720 ◽

1995 ◽

Vol 74 (01) ◽

pp. 449-453 ◽

Cited By ~ 99

Author(s):

Rogier M Bertina ◽

Pieter H Reitsma ◽

Frits R Rosendaal ◽

Jan P Vandenbroucke

Keyword(s):

Risk Factors ◽

Venous Thrombosis ◽

Protein C ◽

Activated Protein C ◽

Factor V Leiden ◽

Factor V

Download Full-text

Polymorphisms in the protein C gene as risk factor for venous thrombosis

Thrombosis and Haemostasis ◽

10.1160/th08-08-0502 ◽

2009 ◽

Vol 101 (01) ◽

pp. 62-67 ◽

Cited By ~ 25

Author(s):

Carine Doggen ◽

Hans Vos ◽

Pieter Reitsma ◽

Frits Rosendaal ◽

Elisabeth Pomp

Keyword(s):

Oral Contraceptive ◽

Venous Thrombosis ◽

Protein C ◽

Contraceptive Use ◽

Factor V Leiden ◽

Factor V ◽

Thrombotic Risk ◽

Control Subjects ◽

Oral Contraceptive Use ◽

Increased Risk

SummaryProtein C is an important inhibitor of blood coagulation. We investigated the effect of two polymorphisms within the promoter region of the protein C gene (C/T at position 2405 and A/G at position 2418) on risk of venous thrombosis and on plasma protein C levels. In addition the combined effect of the two polymorphisms with factor V Leiden and oral contraceptive use was investigated. Previous studies on these polymorphisms were small and were not able to investigate synergistic effects. In the Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis (MEGA study), protein C levels were determined in 2,043 patients with venous thrombosis and 2,857 control subjects, and the two polymorphisms in 4,285 patients and 4,863 control subjects. The CC/GG genotype was associated with the lowest protein C levels. Compared to carriers of the TT/AA genotype – a genotype associated with higher protein C levels – the risk of venous thrombosis in CC/GG carriers was 1.3-fold increased (95% confidence interval 1.09–1.48). The combination of factor V Leiden with the CC/GG genotype led to a 4.7-fold increased risk, compared to non-carriers with the TT/AA genotype. Oral contraceptive use together with the CC/ GG genotype resulted in a 5.2-fold increased risk. In conclusion, the CC/GG genotype is associated with lower levels of protein C and an elevated risk of venous thrombosis compared to the TT/AA genotype. There is no clear synergistic effect of the CC/ GG genotype with factor V Leiden or oral contraceptive use on thrombotic risk.

Download Full-text

Antiphospholipid antibodies and thrombosis: association with acquired activated protein C resistance in venous thrombosis and with hyperhomocysteinemia in arterial thrombosis

Thrombosis and Haemostasis ◽

10.1160/th04-03-0138 ◽

2004 ◽

Vol 92 (12) ◽

pp. 1312-1319 ◽

Cited By ~ 11

Author(s):

Jeannine Kassis ◽

Carolyn Neville ◽

Joyce Rauch ◽

Lambert Busque ◽

Erika Chang ◽

...

Keyword(s):

Venous Thrombosis ◽

Antiphospholipid Antibodies ◽

Arterial Thrombosis ◽

Protein C ◽

Complete Blood Count ◽

Tertiary Care ◽

Activated Protein C ◽

Factor V Leiden ◽

Activated Protein C Resistance ◽

Increased Risk

SummaryAlthough antiphospholipid antibodies (aPL) are associated with thrombosis, it is not known who with aPL is at higher risk for thrombosis. It was the aim of this cross-sectional study to investigate how thrombophilic factors contribute to venous or arterial thrombosis in aPL-positive individuals. In outpatient test centres at two tertiary care hospitals, two hundred and eight (208) persons requiring aPL testing were matched by age, gender and centre to 208 persons requiring a complete blood count. Persons were classified as aPL-positive (having anticardiolipin, lupus anticoagulant and/or anti-β2-glycoprotein I antibodies) or aPL-negative. Several thrombophilic factors were studied using logistic regression modelling. Results showed that the aPL-positive group had three-fold more events (37%) than the aPL-negative group (12%). In unadjusted analyses, clinically important associations were observed between factor V Leiden and venous thrombosis, hyperhomocysteinemia and arterial thrombosis, and activated protein C resistance (APCR) and venous thrombosis (OR, 95% CI = 4.00, 1.35-11.91; 4.79, 2.03-11.33; and 2.03, 1.03-3.97, respectively). After adjusting for recruitment group, persons with both APCR and aPL had a three-fold greater risk (OR, 95% CI = 3.31, 1.30-8.41) for venous thrombosis than those with neither APCR nor aPL. Similarly, after adjusting for hypertension, family history of cardiovascular disease, gender and recruitment group, persons with both hyperhomocysteinemia and aPL had a five-fold increased risk (OR, 95% CI = 4.90, 1.37-17.37) for arterial thrombosis compared to those with neither risk factor. In conclusion, APCR phenotype and hyperhomocysteinemia are associated with a higher risk of venous and arterial thrombosis, respectively, in the presence of aPL.

Download Full-text

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.

Download Full-text