Resistance to activated protein C, the FV: Q506 allele, and venous thrombosis

1998 ◽  
Vol 18 (01) ◽  
pp. 1-10
Author(s):  
A. Hillarp ◽  
S. Rosen ◽  
B. Zöller ◽  
B. Dahlbäck
Keyword(s):  
Venous Thrombosis ◽  
Protein C ◽  
Antithrombin Iii ◽  
Single Point ◽  
Activated Protein C ◽  
Factor Xa ◽  
Protein S ◽  
Single Point Mutation ◽  
Factor V ◽  
Endothelial Cell Surface

SummaryVitamin K-dependent protein C is an important regulator of blood coagulation. After its activation on the endothelial cell surface by thrombin bound to thrombomodulin, it cleaves and inactivates procoagulant cofactors Va and Villa, protein S and intact factor V working as cofactors. Until recently, genetic defects of protein C or protein S were, together with antithrombin III deficiency, the established major causes of familial venous thromboembolism, but they were found in fewer than 5-10% of patients with thrombosis. In 1993, inherited resistance to activated protein C (APC) was described as a major risk factor for venous thrombosis. It is found in up to 60% of patients with venous thrombosis. In more than 90% of cases, the molecular background for the APC resistance is a single point mutation in the factor V gene, which predicts substitution of an arginine (R) at position 506 by a glutamine (Q). Mutated factor V (FV: Q506) is activated by thrombin or factor Xa in normal way, but impaired inactivation of mutated factor Va by APC results in life-long hypercoagulability. The prevalence of the FV:Q506 allele in the general population of Western countries varies between 2 and 15%, whereas it is not found in several other populations with different ethnic backgrounds. Owing to the high prevalence of FV:Q506 in Western populations, it occasionally occurs in patients with deficiency of protein S, protein C, or antithrombin III. Individuals with combined defects suffer more severely from thrombosis, and often at a younger age, than those with single defects, suggesting severe thrombophilia to be a multigenetic disease.

scholarly journals Molecular mechanisms of activated protein C resistance. Properties of factor V isolated from an individual with homozygosity for the Arg506 to Gln mutation in the factor V gene

1996 ◽  
Vol 313 (2) ◽  
pp. 467-472 ◽  
Author(s):  
Cristina APARICIO ◽  
Björn DAHLBÄCK
Keyword(s):  
Risk Factor ◽  
Protein C ◽  
Molecular Mechanisms ◽  
Single Point ◽  
Activated Protein C ◽  
Factor Xa ◽  
Single Point Mutation ◽  
Factor V ◽  
Apc Resistance ◽  
Anticoagulant System

Resistance to activated protein C (APC), which is the most prevalent pathogenetic risk factor of thrombosis, is linked to a single point-mutation in the factor V (FV) gene, which predicts replacement of Arg (R) at position 506 with a Gln (Q). This mutation modifies one of three APC-cleavage sites in the heavy chain of activated FV (FVa), suggesting that mutated FVa (FVa:Q506) is at least partially resistant to APC-mediated degradation. To elucidate the molecular mechanisms of APC-resistance and to investigate the functional properties of FV in APC resistance, FV:Q506 was purified from an individual with homozygosity for the Arg to Gln mutation. Intact and activated FV:Q506 were demonstrated to convey APC resistance to FV-deficient plasma. Thrombin- or factor Xa-activated FV:Q506 were found to be approx. 10-fold less sensitive to APC-mediated degradation than normal FVa, at both high and low phospholipid concentrations. The degradation pattern observed on Western blotting suggested that FVa:Q506 was not cleaved at position 506. However, it was slowly cleaved at Arg306, which explains the partial APC sensitivity of FVa:Q506. FV is initially activated during clotting and then rapidly inactivated in a process which depends on the integrity of the protein C anticoagulant system. During clotting of APC-resistant plasma, FV:Q506 was activated in a normal fashion, but then only partially inactivated. In conclusion, the reduced sensitivity of FVa:Q506 to APC-mediated degradation is the molecular basis for the life-long hypercoagulable state which constitutes a risk factor for thrombosis in APC-resistant individuals.

Simple and Reliable Factor V Genotyping by PNA-Mediated PCR Clamping

1998 ◽  
Vol 79 (04) ◽  
pp. 773-777 ◽  
Author(s):  
Moira Behn ◽  
Marcus Schuermann
Keyword(s):  
Venous Thrombosis ◽  
Large Scale ◽  
Single Point ◽  
Activated Protein C ◽  
Factor V Leiden ◽  
Single Point Mutation ◽  
Factor V ◽  
Apc Resistance ◽  
Novel Approach ◽  
Pcr Rflp

SummaryResistance to activated protein C (APC resistance) is the most common cause of thrombophilia and linked to a single point mutation in the factor V gene (G>A transition at nucleotide 1691). In the past, several PCR based methods have been proposed to determine the allelostatus of individual patients from small amounts of blood DNA including PCR followed by restriction fragment length polymorphism detection (PCR-RFLP), PCR using sequence-specific primers (PCR-SSP) and oligonucleotide ligation assay (OLA). Here, we present a novel approach based on the method of peptide nucleic acid(PNA)-mediated PCR clamping which is extremely sensitive to base pair mismatches. If PNAs specific for the two allelic variants are applied separately in each case a clear discrimination between a heterozygous or homozygous normal or homozygous Factor V Leiden status is possible and no further confirmation step is required. In a prospective study, 60 patients with suspected venous thrombosis events were tested and compared to the conventional PCR-RFLP technique. The concordance between both methods was 100%. PNA-based factor V genotyping, therefore, should be considered for large scale screening of those patients considered to be at risk for deep venous thrombosis.

SIMULTANEOUS PRODUCTION OF ENDOTHELIAL CELL-DERIVED PROTEIN S AND FACTOR V, AND INACTIVATION OF FACTOR Va AT THE ENDOTHELIAL CELL SURFACE

1987 ◽  
Author(s):  
P v d Waart ◽  
K T Preissner ◽  
U Delvos ◽  
G Müller-Berghaus
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Surface ◽  
Conditioned Medium ◽  
Protein C ◽  
Activated Protein C ◽  
Protein S ◽  
Factor V ◽  
Endothelial Cell Surface ◽  
Factor Va

Several proteins synthesized and expressed by endothelial cells are involved in the regulation of coagulation. The synthesis and expression of factor V and protein S has been demonstrated in independent studies. The present work evaluates the simultaneous synthesis and expression of bovine factor V and protein S and the effect of endothelial protein S on the inactivation of endothelial factor Va by activated protein C. The accumulation of both proteins in conditioned medium was detected by SDS-PAGE followed by immunoblotting, and their activities were tested by functional assays. The synthesis of protein S and factor V per 105 cells over 24 h amounted up to 2 ng protein S and 440 ng factor V, respectively. The addition of thrombin did not increase the yield of synthesized cofactors. Thrombin did neither proteolyse protein S on endothelial cells nor in a purified system in the presence of thrombomodulin and calcium ions. Factor V was secreted partly in its activated form as evidenced by the appearance of active intermediates with M = 220,000-280,000 on immunoblots as well as by only a three-Fold further activation of factor V/Va following addition of thrombin. The rate constant for the inactivation of factor Va by activated protein C was only two-fold higher for factor Va derived from cells cultured in the presence of vitamin K as compared in the presence of warfarin. For the inactivation of comparable factor Va concentrations in conditioned medium a 10-fold higher and on endothelial cells a 40-fold higher concentration of activated protein C was required to obtain similar inactivation rates of factor Va as compared to a purified system. These results suggest that resting endothelial cells contain a factor V activator, and that a regulatory mechanism is operative on the endothelial cell surface that suppresses the inactivation potential of activated protein C/ protein S.

State-of-the-Art Review: Activated Protein C Resistance: Clinical Implications

1997 ◽  
Vol 3 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Bengt Zöller ◽  
Andreas Hillarp ◽  
Björn Dahlbäck
Keyword(s):  
Risk Factors ◽  
Venous Thrombosis ◽  
Protein C ◽  
Activated Protein C ◽  
Protein S ◽  
Factor V ◽  
Thrombotic Risk ◽  
Western Countries ◽  
Apc Resistance ◽  
Increased Risk

The discovery of inherited resistance to activated protein C (APC) as a major risk factor for venous thrombosis has dramatically improved our understanding of the pathogenesis of venous thrombosis. In a majority of cases, APC resistance is associated with a single point mutation in the factor V gene (FV) that results in substitution of arginine, R, at position 506 by glutamine, Q. (FV:Q506). The mutation renders factor Va partially resistant to degradation by APC. A functional APC resistance test, which includes predilution of the patient plasma with factor V-deficient plasma, is found to be 100% sensitive and specific for the presence of FV:Q506 and is useful as a screening assay. Carriers of the FV:Q506 allele have increased thrombin generation, resulting in hypercoagulability and a lifelong increased risk of venous thrombosis. In Western countries, APC resistance due to the FV mutation is present in 20-60% of thrombosis patients and in 1-15% of healthy controls, whereas the mutation is virtually absent from ethnic groups other than Caucasians. This may explain the high incidence of venous thrombosis in Western countries. The thrombotic risk in APC-resistant individuals may be further increased by other genetic defects, e.g., protein C or protein S deficiency, and by exposure to circumstantial risk factors, e.g., oral contraceptives, pregnancy, immobilization, and surgery. The question is thus raised as to whether general screening for APC resistance before circumstantial risk factors occur is warranted in Western countries. Key Words: Factor V—APC resistance-Protein C-Protein S—Thrombosis—Mutation.

scholarly journals Use of a generally applicable tissue factor--dependent factor V assay to detect activated protein C-resistant factor Va in patients receiving warfarin and in patients with a lupus anticoagulant

Blood ◽  
1995 ◽  
Vol 85 (7) ◽  
pp. 1704-1711 ◽  
Author(s):  
DT Le ◽  
JH Griffin ◽  
JS Greengard ◽  
V Mujumdar ◽  
SI Rapaport
Keyword(s):  
Venous Thrombosis ◽  
Tissue Factor ◽  
Lupus Anticoagulant ◽  
Protein C ◽  
Dna Analysis ◽  
Activated Protein C ◽  
Protein S ◽  
Factor V ◽  
Factor Va ◽  
Abnormal Results

The original activated partial thromboplastin time-based assay for activated protein C (APC)-resistant factor Va (FVa) requires carefully prepared fresh plasma and cannot be used in patients receiving warfarin or in patients with antiphospholipid antibodies. A new test is described here that circumvents these limitations and distinguishes without overlap heterozygotes for APC-resistant FVa from persons with normal FV. A diluted test plasma is incubated with an FV-deficient substrate plasma and tissue factor and then clotted with Ca2+ or Ca2+ plus APC. Test results are independent of the FV level or the dilution of the test plasma used. Of 39 controls, 37 gave normal results. Two controls (5%) gave results indicative of APC resistant FVa and on DNA analysis were found to be heterozygous for FV R506Q. Twenty of 21 randomly selected patients receiving warfarin gave normal results. In the single patient with abnormal results, heterozygous FV R506Q was confirmed by DNA analysis. Two of 15 patients with protein S deficiency and 5 of 29 patients with a lupus anticoagulant had abnormal results. APC resistance caused by FV R506Q was confirmed in the five of these seven patients available for DNA analysis. APC-resistant FVa was also detected in 10 of 21 (46%) stored plasma from unrelated patients with venous thrombosis and negative earlier evaluation for a lupus anticoagulant or a deficiency of protein C, protein S, or antithrombin, which confirms a high incidence of this defect among patients with venous thrombosis.

Lack of Association between Inherited Thrombophilic Risk Factors and Idiopathic Sudden Sensorineural Hearing Loss in Italian Patients

2006 ◽  
Vol 115 (3) ◽  
pp. 195-200 ◽  
Author(s):  
Gabriella Cadoni ◽  
Simona Scipione ◽  
Bianca Rocca ◽  
Stefania Agostino ◽  
Carmelo La Greca ◽  
...  
Keyword(s):  
Risk Factors ◽  
Protein C ◽  
Antithrombin Iii ◽  
Activated Protein C ◽  
Protein S ◽  
Mthfr C677t ◽  
Sudden Sensorineural Hearing Loss ◽  
Prothrombin G20210a ◽  
Factor V ◽  
Activated Protein C Resistance

Objectives: We investigated the presence of congenital thrombophilic risk factors in a population of consecutive Italian patients affected by idiopathic sudden sensorineural hearing loss (SSNHL). Methods: We investigated 48 patients with idiopathic SSNHL for the presence of congenital thrombophilic risk factors. The factor V Leiden G1691A, the prothrombin G20210A allele, and methylenetetrahydrofolate reductase (MTHFR) C677T genotypes were investigated. Allele frequencies and genotype distribution of all factors found in patients were compared to those of 48 healthy subjects of the same ethnic background by χ2 and odds-ratio analysis. Odds ratios and 95% confidence intervals were calculated for allele and genotype frequencies of all thrombophilia variants. Statistical significance was accepted with a p value of less than .05. We also performed the following blood tests: hemacytometric analysis including platelet count, prothrombin time, activated partial thromboplastin time, fibrinogen, erythrocyte sedimentation rate, C-reactive protein, protein S, protein C, antithrombin III, and activated protein C resistance. Results: In our series, we did not find an association between SSNHL and abnormal levels of antithrombin III, protein C, protein S, D-dimer, or fibrinogen; activated protein C resistance; or factor V G1691 A, prothrombin G20210A, or MTHFR C677T mutations. Conclusions: At present, the few studies regarding genetic polymorphisms of congenital thrombophilic factors in SSNHL are not conclusive. According to our data, factor V G1691A, prothrombin G20210A, and MTHFR C677T variants should be not considered risk factors for SSNHL. Further large prospective studies are needed to provide currently lacking information and to improve our knowledge in the field before we recommend the determination of genetic polymorphism in SSNHL as routine practice.

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

1995 ◽  
Vol 74 (01) ◽  
pp. 449-453 ◽  
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

The Frequency of Type I Heterozygous Protein S and Protein C Deficiency in 141 Unrelated Young Patients with Venous Thrombosis

1988 ◽  
Vol 59 (01) ◽  
pp. 018-022 ◽  
Author(s):  
C L Gladson ◽  
I Scharrer ◽  
V Hach ◽  
K H Beck ◽  
J H Griffin
Keyword(s):  
Venous Thrombosis ◽  
Protein C ◽  
Antithrombin Iii ◽  
Young Patients ◽  
Protein S ◽  
Type I ◽  
Protein S Deficiency ◽  
Protein C Deficiency ◽  
Low Protein ◽  
S Deficiency

SummaryThe frequency of heterozygous protein C and protein S deficiency, detected by measuring total plasma antigen, in a group (n = 141) of young unrelated patients (<45 years old) with venous thrombotic disease was studied and compared to that of antithrombin III, fibrinogen, and plasminogen deficiencies. Among 91 patients not receiving oral anticoagulants, six had low protein S antigen levels and one had a low protein C antigen level. Among 50 patients receiving oral anticoagulant therapy, abnormally low ratios of protein S or C to other vitamin K-dependent factors were presented by one patient for protein S and five for protein C. Thus, heterozygous Type I protein S deficiency appeared in seven of 141 patients (5%) and heterozygous Type I protein C deficiency in six of 141 patients (4%). Eleven of thirteen deficient patients had recurrent venous thrombosis. In this group of 141 patients, 1% had an identifiable fibrinogen abnormality, 2% a plasminogen abnormality, and 3% an antithrombin III deficiency. Thus, among the known plasma protein deficiencies associated with venous thrombosis, protein S and protein C. deficiencies (9%) emerge as the leading identifiable associated abnormalities.

Sign in / Sign up

Export Citation Format

Share Document