Factor VII Gene Polymorphisms Contribute About One Third of the Factor VII Level Variation in Plasma

Genetic Landscape of Factor VII Deficiency: Insights from a Comprehensive Analysis of Pathogenic Variants and Their Impact on Coagulation Activity

Congenital factor VII (FVII) deficiency is a rare genetic bleeding disorder characterized by deficient or reduced activity of coagulation FVII. It is caused by genetic variants in the F7 gene. We aimed to evaluate the rate of detection of pathogenic variants in the F7 gene in a large group of patients with FVII deficiency and investigate the correlations between the F7 genotype and FVII activity (FVII:C). Moreover, the influence of the common genetic variant rs6046: c.1238G>A; p.(Arg413Gln), designated as the M2 allele, on FVII:C was investigated. Genetic analysis of the F7 gene was performed on 704 index patients (IPs) using either direct Sanger- or next-generation sequencing. Genetic variants were detected in 390 IPs, yielding a variant detection rate (VDR) of 55%. Notably, the VDR exhibited a linear decline with increasing FVII:C levels. We identified 124 genetic variants, of which 48 were not previously reported. Overall, the frequency of the M2 allele was considerably higher in patients with mild deficiency (FVII:C > 20 IU/dl). Furthermore, IPs lacking an identified pathogenic variant exhibited a significantly higher prevalence of the M2 allele (69%) compared to IPs with a disease-causing variant (47%). These results strongly support the association of the M2 allele with decreased FVII:C levels. This study shows the utility of FVII:C as a predictive marker for identifying pathogenic variants in patients with FVII deficiency. The M2 allele contributes to the reduction of FVII:C levels, particularly in cases of mild deficiency.

Contribution of factor VII polymorphisms to coagulopathy in patients with isolated traumatic brain injury

BACKGROUND

Coagulopathy is a severe complication of traumatic brain injury (TBI) and can cause secondary injuries and death. Decrease of FVII activity contributes to the coagulopathy and progressive hemorrhagic injury (PHI) in patients with isolated TBI. Some polymorphic loci of coagulation factor VII (FVII) are shown to be essential for FVII activity. However, the relationship between FVII gene polymorphisms and coagulopathy in patients with isolated TBI is still unknown. Therefore, the present study aimed to investigate the relationship between FVII gene polymorphisms and plasma FVIIa levels, and assess whether FVII polymorphisms were associated with TBI-related coagulopathy, PHI, and 6 months GOS in patients with isolated TBI.

METHODS

One-hundred-forty-nine patients with isolated TBI (from East of China) admitted to Huashan Hospital's Neurological Trauma Center from March 2012 to March 2016 were enrolled in this study. The Polymorphism-Polymerase Chain Reaction (PCR) method was used to analyze the five FVII polymorphism loci (-323P0/P10, R353Q, -401G/T, -402G/A, and -670A/C) of these patients. Patients' blood was collected to test the activated partial thromboplastin time, international normalized ratio, platelet, and FVIIa concentrations. Other clinical characteristics were also recorded.

RESULTS

The minor alleles of three genotypes of -323 P0/P10, R353Q, and -401G/T each independently associated with 23.3%, 28.6%, and 27.6% lower FVIIa levels, respectively. These polymorphisms explained 21% of the total variance of FVIIa levels (adjusted R²:0.206). The genotype of -323P0/P10 was an independent risk factor for coagulopathy (OR = 2.77, p = 0.043) and PHI (OR = 3.47, p = 0.03) after adjustment for confounding factors in the logistic regression model. Polymorphisms of FVII were not independently associated with 6 months Glasgow Outcome Scale (GOS) of isolated TBI patients.

CONCLUSION

-323P0/P10, R353Q, and -401 G/T genotypes were associated with FVIIa levels. -323P0/P10 genotype was independently associated with traumatic coagulopathy and PHI in isolated TBI patients.

Biochemical, molecular and clinical aspects of coagulation factor VII and its role in hemostasis and thrombosis

Activated factor VII (FVIIa), the first protease of clotting, expresses its physiological procoagulant potential only after complexing with tissue factor (TF) exposed to blood. Deep knowledge of the FVIIa-TF complex and F7 gene helps to understand the Janus-faced clinical findings associated to low or elevated FVII activity (FVIIc). Congenital FVII deficiency, the most frequent among the recessively inherited bleeding disorders, is caused by heterogeneous mutations in the F7 gene. Complete FVII deficiency causes perinatal lethality. A wide range of bleeding symptoms, from life-threatening intracranial hemorrhage to mild mucosal bleeding, is observed in patients with apparently modest differences in FVIIc levels. Though clinically relevant FVIIc threshold levels are still uncertain, effective management, including prophylaxis, has been devised, substantially improving the quality of life of patients. The exposure of TF in diseased arteries fostered investigation on the role of FVII in cardiovascular disease. FVIIc levels were found to be predictors of cardiovascular death and to be markedly associated to F7 gene variation. These genotype-phenotype relationships are among the most extensively investigated in humans. Genome-wide analyses extended association to numerous loci that, together with F7, explain >50% of FVII level plasma variance. However, the ability of F7 variation to predict thrombosis was not consistently evidenced in the numerous population studies. Main aims of this review are to highlight i) the biological and clinical information that distinguishes FVII deficiency from the other clotting disorders and ii) the impact exerted by genetically predicted FVII level variation on bleeding as well as on the thrombotic states.

Association Between R353Q (rs6046) Polymorphism in Factor VII with Coronary Heart Disease

A number of studies have showed the relationship between R353Q (rs6046) polymorphism in factor VII gene and coronary heart disease (CHD). However, the results remain controversial due to the limitations of the research objects and small sample size of individual study. We conducted this meta-analysis to validate the association between R353Q (rs6046) polymorphism and the risk of CHD.The relevant data was collected up to March 25, 2019 from PubMed, Web of Science, CNKI, and Wanfang databases. We examined all eligible studies using the Newcastle-Ottawa Quality Assessment Scale (NOS). The odds ratio (OR) and its corresponding 95% confidence interval (CI) were adopted to evaluate the relationship between the R353Q (rs6046) polymorphism and CHD. Stata version 14.0 (Stata Corporation, USA) was used in all statistical tests.There were at least 28 eligible studies, including 14626 cases and 17994 controls, included in our meta-analysis. R353Q (rs6046) polymorphism was associated with the reduced risk of CHD in four genetic models: allele model (Q versus R: OR = 0.79, 95% CI: 0.69 to 0.90, P < 0.001, I² = 56.4%), homozygote (co-dominant) model (QQ versus RR: OR = 0.72, 95% CI = 0.58 to 0.92, P = 0.004, I² = 5.8%), heterozygote (co-dominant) model (RQ versus RR: OR = 0.71, 95% CI = 0.58 to 0.86, P = 0.001, I² = 75.4%), and dominant model (RQ+QQ versus RR: OR = 0.74, 95% CI = 0.63 to 0.865, P < 0.001, I² = 64.1%) excluding recessive model (QQ versus RR+RQ: OR = 0.86, 95% CI = 0.57 to 1.28, P = 0.447, I² = 51.6%).The results of the current meta-analysis suggested that R353Q (rs6046) polymorphism was associated with the reduced risk of CHD, especially in Asians.

The EAHAD blood coagulation factor VII variant database

Hereditary blood coagulation factor VII (FVII) deficiency is a rare autosomal recessive bleeding disorder resulting from variants in the gene encoding FVII (F7). Integration of genetic variation with functional consequences on protein function is essential for the interpretation of the pathogenicity of novel variants. Here, we describe the integration of previous locus-specific databases for F7 into a single curated database with enhanced features. The database provides access to in silico analyses that may be useful in the prediction of variant pathogenicity as well as cross-species sequence alignments, structural information, and functional and clinical severity described for each variant, where appropriate. The variant data is shared with the F7 Leiden Open Variation Database. The updated database now includes 221 unique variants, representing gene variants identified in 728 individuals. Single nucleotide variants are the most common type (88%) with missense representing 74% of these variants. A number of variants are found with relatively high minor allele frequencies that are not pathogenic but contribute significantly to the likely pathogenicity of coinherited variants due to their effect on FVII plasma levels. This comprehensive collection of curated information significantly aids the assessment of pathogenicity.

Aptamer-modified FXa generation assays to investigate hypercoagulability in plasma from patients with ischemic heart disease

BACKGROUND

High plasma levels of activated Factor VII-Antithrombin complex (FVIIa-AT) have been associated with an increased risk of cardiovascular mortality in patients with stable coronary artery disease (CAD).

OBJECTIVES

To investigate if FVIIa-AT levels are associated with activated factor X generation (FXaG) in modified assays.

PATIENTS/METHODS

Forty CAD patients were characterized for FVIIa-AT levels by ELISA and for FXaG in plasma. Novel fluorogenic FXaG assays, based on aptamers inhibiting thrombin and/or tissue factor pathway inhibitor (TFPI), were set up.

RESULTS

FXaG correlated with FVIIa-AT levels (R_AUC = 0.393, P = 0.012). The combination of thrombin inhibition and FXaG potentiation by using anti-thrombin and anti-TFPI aptamers, respectively, favors the study of time parameters. The progressive decrease in lag time from the lowest to the highest FVIIa-AT quartile was magnified by combining TFPI and thrombin inhibitory aptamers, thus supporting increased FXaG activity in the coagulation initiation phase. By exploring FXaG rates across FVIIa-AT quartiles, the largest relative differences were detectable at the early times (the highest versus the lowest quartile; 5.0-fold, P = 0.005 at 45 s; 3.5-fold, P = 0.001 at 55 s), and progressively decreased over time (2.3-fold, P = 0.002 at 75 s; 1.8-fold, P = 0.008 at 95 s; 1.6-fold, P = 0.022 at 115 s). Association between high FVIIa-AT levels and increased FXaG was independent of F7 -323 A1/A2 polymorphism influencing FVIIa-AT levels.

CONCLUSIONS

High FVIIa-AT plasma levels were associated with increased FXaG. Hypercoagulability features were specifically detectable in the coagulation initiation phase, which may have implications for cardiovascular risk prediction by either FVIIa-AT complex measurement or modified FXaG assays.

Polymorphism of R353Q (rs6046) in factor VII and the risk of myocardial infarction: A systematic review and meta-analysis

OBJECTIVE

Genetic components substantially contribute to the development of myocardial infarction (MI), and R353Q polymorphism (rs6046) in FVII gene has been suspected to be associated with the risk of MI.

METHODS

A meta-analysis was conducted on the links between R353Q polymorphism and the susceptibility of MI. A comprehensive literature search was performed on 8 electronic databases. The main effects of the genotypes were estimated using a logistic regression approach. The odds ratios with 95% confidence intervals were calculated using the conventional summary method meta-analysis. The possible sources of heterogeneity among the included studies were explored using meta-regression analysis and subgroup analysis.

RESULTS

A total of 18 eligible case-control studies, comprising of 4701 cases and 5329 controls, were included. No overall statistical relationship was identified between R353Q and MI by any of the genetic models. The meta-regression demonstrated that the Asian population, body mass index (BMI) category, and diabetes affected the heterogeneity. In addition, subgroup analyses showed that heterogeneities were identified in Asian population and BMI category, which highly agree with the results of meta-regression.

CONCLUSIONS

The current meta-analysis suggested that R353Q polymorphism was not associated with the MI risk. Asian population, BMI category, and diabetes might be related to the incidence of MI. However, large-scale, case-control studies with rigorous designs are essential to provide accurate evidence.

Factor VII deficiency: a novel missense variant and genotype-phenotype correlation in patients from Southern Italy

This study aimed at attempting to correlate genotype and phenotype in factor VII deficiency. Here, we present molecular and clinical findings of 10 patients with factor VII deficiency. From 2013 to 2016, 10 subjects were referred to our center because of a prolonged prothrombin time identified during routine or presurgery examinations or after a laboratory assessment of a bleeding episode. Mutation characterization was performed using the bioinformatics applications PROMO, SIFT, and Polyphen-2. Structural changes in the factor VII protein were analyzed using the SPDB viewer tool. Of the 10 variants we identified, 1 was responsible for a novel missense change (c.1199G>C, p.Cys400Ser); in 2 cases we identified the c.-54G>A and c.509G>A (p.Arg170His) polymorphic variants in the 5′-upstream region of the factor VII gene and exon 6, respectively. To our knowledge, neither of these polymorphic variants has been described previously in factor VII-deficient patients. In silico predictions showed differences in binding sites for transcription factors caused by the c.-54G>A variant and a probable damaging effect of the p.Cys400Ser missense change on factor VII active conformation, leading to breaking of the Cys400-Cys428 disulfide bridge. Our findings further suggest that, independently of factor VII levels and of variants potentially affecting factor VII levels, environmental factors, e.g., trauma, could heavily influence the clinical phenotype of factor VII-deficient patients.

F7 gene variants modulate protein levels in a large cohort of patients with factor VII deficiency. Results from a genotype-phenotype study

Congenital factor VII (FVII) deficiency is a rare bleeding disorder caused by mutations in F7 gene with autosomal recessive inheritance. A clinical heterogeneity with poor correlation with FVII:C levels has been described. It was the objective of this study to identify genetic defects and to evaluate their relationships with phenotype in a large cohort of patients with FVII:C<50 %. One hundred twenty-three probands were genotyped for F7 mutations and three polymorphic variants and classified according to recently published clinical scores. Forty out of 123 patients (33 %) were symptomatic (43 bleedings). A severe bleeding tendency was observed only in patients with FVII:C<0.10 %. Epistaxis (11 %) and menorrhagia (32 % of females in fertile age) were the most frequent bleedings. Molecular analysis detected 48 mutations, 20 not reported in the F7 international databases. Most mutations (62 %) were missense, large deletions were 6.2 %. Compound heterozygotes/homozygotes for mutations presented lower FVII:C levels compared to the other classes (Chi2=43.709, p<0,001). The polymorphisms distribution was significantly different among the three F7 genotypic groups (Chi2=72.289, p<0,001). The presence of truncating mutations was associated with lowest FVII:C levels (Chi2=21.351, p=0.002). This study confirms the clinical and molecular variability of the disease and the type of symptoms. It shows a good correlation between the type of F7 mutation and/or polymorphisms and FVII:C levels, without a direct link between FVII:C and bleeding tendency. The results suggest that large deletions are underestimated and that they represent a common mechanism of F7 gene inactivation which should always be investigated in the diagnostic testing for FVII deficiency.

Factor VII Deficiency: Clinical Phenotype, Genotype and Therapy

Factor VII deficiency is the most common among rare inherited autosomal recessive bleeding disorders, and is a chameleon disease due to the lack of a direct correlation between plasma levels of coagulation Factor VII and bleeding manifestations. Clinical phenotypes range from asymptomatic condition—even in homozygous subjects—to severe life-threatening bleedings (central nervous system, gastrointestinal bleeding). Prediction of bleeding risk is thus based on multiple parameters that challenge disease management. Spontaneous or surgical bleedings require accurate treatment schedules, and patients at high risk of severe hemorrhages may need prophylaxis from childhood onwards. The aim of the current review is to depict an updated summary of clinical phenotype, laboratory diagnosis, and treatment of inherited Factor VII deficiency.

Biomarkers for arterial and venous thrombotic disorders

The haemostatic system maintains the blood in a fluid state, but allows rapid clot formation at sites of vascular injury to prevent excessive bleeding. Unbalances within the haemostatic system can lead to thrombosis. Inspite of successful research our understanding of the disease pathogenesis is still incomplete. There is great hope that genetic, genomic, and epigenetic discoveries will enhance the diagnostic capability, and improve the treatment options. During the preceding 20 years, the identification of polymorphisms and the elucidation of their role in arterial and venous thromboses became an important area of research. Today, a large body of data is available regarding associations of single nucleotide polymorphisms (SNPs) in candidate genes with plasma concentrations and e. g. the risk of ischaemic stroke or myocardial infarction. However, the results for individual polymorphisms and genes are often controversial. It is now well established that besides acquired also hereditary risk factors influence the occurrence of thrombotic events, and environmental factors may add to this risk. Currently available statistical methods are only able to identify combined risk genotypes if very large patient collectives (>10,000 cases) are tested, and appropriate algorithms to evaluate the data have yet to be developed. Further research is needed to understand the functional effects of genetic variants in genes of blood coagulation proteins that are critical to the pathogenesis of arterial and venous thrombotic disorders. In this review genetic variants in selected genes of the haemostatic system and their relevance for arterial and venous thrombosis will be discussed.

Genetic polymorphisms and the risk of myocardial infarction in patients under 45 years of age

This study investigates the potential role of 17 chosen polymorphisms in 15 candidate genes and the risk of myocardial infarction in patients under 45 years of age. The study consists of 271 patients with myocardial infarction and 141 controls. The analysis of genetic polymorphisms was performed using the PCR–RFLP method. Of the chosen polymorphisms, two (Leu125Val PECAM1 and A1/A2 FVII) are related to myocardial infarction and two (C677T MTHFR and 5A/6A MMP3) to advanced stenosis in arterial vessels (> 75%). We also found that the frequency of some combinations among the analyzed genes and environmental factors varied between the patient and control groups.

Contribution of coagulation factor VII R353Q, -323P0/10 and HVR4 polymorphisms to coronary artery disease in Tunisians

We examined the contribution of two factor VII (FVII) bi-allelic (R353Q, -323P0/10) and one tandem repeat (HVR4) polymorphisms to the risk of coronary artery disease (CAD) in Tunisians. Study subjects comprised 308 CAD patients and 312 age-, gender- and ethnically-matched controls. Regression analysis was used in assessing the FVII association to CAD risk. While the distribution of -323P0/10 alleles and genotypes were comparable between cases and controls, marginal association of the R353Q variant was noted, with the Q allele (19.1 vs. 23.8%; P = 0.05) and Q allele-containing genotypes (R/Q + Q/Q; 33.8 vs. 48.0%) being slightly under-represented in cases than in controls. On the other hand, four alleles of FVII microsatellite HVR4 were detected at variable frequencies in Tunisians, and comprised H6 (63.2%), H7 (33.8%), and to lesser extents H5 (1.9%) and H8 (0.8%). Of these, the H7 variant was under-represented in patients [P = 0.038; OR (95%CI) = 0.75 (0.58-0.97)]. Of the major genotypes detected (H6/H6, H6/H7, H7/H7) only H6/H6 was positively associated with CAD [P = 0.047; OR (95%CI) = 1.39 (1.00-1.94)]. In conclusion, our study underscores the role of polymorphisms in the FVII gene in modulating the susceptibility to CAD in (North African) Tunisian Arabs.

Lethal factor VII deficiency due to novel mutations in the F7 promoter: functional analysis reveals disruption of HNF4 binding site

Hereditary factor VII (FVII) deficiency is a rare autosomal recessive disorder. Deleterious mutations that prevent the synthesis of any amount of functional FVII have been associated with life-threatening haemorrhage in neonates. Here we report two infants, of Maghrebian origin, who suffered a fatal spontaneous cerebral haemorrhage. Investigation of the molecular basis for their severe FVII deficiency revealed novel mutations in a homozygous state within the F7 gene promoter: a single nucleotide substitution (c.-65G>C) and a 2bp deletion (c.-60_-59delTT). To determine whether these promoter variants were responsible for the FVII deficiency, computer-assisted sequence analyses were performed. The data predicted a disrupted binding of both HNF4 and COUP-TF transcription factors with each variant. Concordantly, experimental results revealed an altered HNF4-induced transactivation in the promoter mutated variants. The execution of functional tests is critical to ensuring a complete understanding of the effect of any promoter mutant on FVII deficiency. Only then can an accurate molecular diagnosis be made and further genetic counselling and prenatal diagnosis be offered.

A novel missense mutation close to the charge-stabilizing system in a patient with congenital factor VII deficiency

Congenital factor VII (FVII) deficiency is a rare autosomal recessive bleeding disorder. Its clinical manifestation and mutational spectrum are highly variable. The purpose of this study was to identify and characterize the mutation causing the FVII deficiency in a Chinese patient and his family. The FVII gene was analyzed by genomic DNA sequencing, and the FVII levels in patient's plasma were measured with an enzyme-linked immunoabsorbent assay (ELISA) and one-stage prothrombin time based method. In addition, the FVII-Phe190 mutant identified in the pedigree was expressed in the HEK293 cells, and the subcellular localization experiments in the Chinese hamster ovary (CHO) cells were performed. The patient had a prolonged prothrombin time and low levels of both FVII antigen and activity, and two heterozygous mutations were identified in F7 gene (NG-009262.1): a g.15975 G>A in the splice receptor site of intron 6 and a novel g.16750 C>T in exon 8 resulting in Ser190 to Phe190 replacement. In expression experiments, the reduced antigen and activity levels of FVII-Phe190 in the culture medium were found, whereas an ELISA and Western blotting analysis of FVII revealed that mutant FVII-Phe190 was synthesized in the cells as the wild-type FVII-Ser190. And FVII-Phe190 was found in endoplasmic reticulum and Golgi apparatus. Compound heterozygous mutations in F7 gene should be responsible for the FVII deficiency in this patient. The FVII-Phe190 can normally be synthesized and transported from endoplasmic reticulum to Golgi apparatus, but degraded or inefficiently secreted.

A retrospective analysis of 157 surgical procedures performed without replacement therapy in 83 unrelated factor VII-deficient patients

BACKGROUND

 Inherited factor (F)VII deficiency is the commonest of the rare bleeding disorders, with a wide set of hemorrhagic features. Other than for the severe clinical forms (for which treatment guidelines are well defined), consistent recommendations regarding perioperative replacement management do not exist for mild and asymptomatic FVII-deficient patients.

OBJECTIVES

 The present study aimed to evaluate the influence of bleeding history, FVII procoagulant activity levels (FVII:C) and the type of surgical procedure on the management of inherited FVII-deficient patients before surgery.

PATIENTS

 One hundred and fifty-seven surgical procedures, performed without replacement therapy, in 83 unrelated FVII-deficient patients (median FVII:C=5%, range 0.6%-35%) were analyzed.

RESULTS

 The overall bleeding rate was 15.3%. We found a significant relationship between previous deep traumatic hematomas and bleeding at surgery, although relationships with previous common epistaxis, easy bruising and menorrhagia were not significant. The receiver-operating characteristic (ROC) curve analysis performed on the first 83 procedures allowed us to define a cut-off value of 7% with a sensitivity of 87% (negative predictive value: 94%). To enhance the sensitivity, and to take into account the potential variation resulting from non-standardized FVII:C measurements, we would suggest applying a threshold of 10%.

CONCLUSION

 We have proposed recommendations for the perioperative management of FVII-deficient patients based on FVII:C levels, a thorough bleeding history and the type of surgery involved. By applying these recommendations, minor procedures that risk only external or controlled hemorrhage can be performed in asymptomatic or mildly affected adults, even those with FVII:C levels below 10%.

R353Q polymorphism in the factor VII gene and cardiovascular risk in Heterozygous Familial Hypercholesterolemia: a case-control study

Background

Heterozygous Familial Hypercholesterolemia (FH) is a genetic disorder characterized by a high risk of cardiovascular disease. Certain polymorphisms of the factor VII gene have been associated with the development of coronary artery disease and there is a known association between factor VII levels and polymorphic variants in this gene. To date, no study has evaluated the association between factor VII and coronary artery disease in patients with FH.

Results

This case-control study comprised 720 patients (546 with FH and 174 controls). We determined the prevalence and allele frequencies of the R353Q polymorphism of factor VII, the plasma levels of factor VII antigen (FVII Ag) and whether they could be predictive factors for cardiovascular risk. 75% (410) of the patients with FH were RR, 23% (127) RQ and 1.6% (9) QQ; in the control group 75.3% (131) were RR, 21.3% (37) RQ and 3.4% (6) QQ (p = 0.32). No statistically significant associations were observed in the distribution of genotypes and allele frequencies between case (FH) and control groups. Nor did we find differences when we evaluated the relationship between the R353Q polymorphism and cardiovascular risk (including coronary disease, ischemic stroke and peripheral arterial disease), either in the univariate analysis or after adjustment for sex, age, arterial hypertension, body mass index, xanthomas, diabetes, smoking, HDLc and LDLc and lipid-lowering treatment. The FVII Ag concentrations behaved in a similar fashion, with no differences for the interaction between controls and those with FH (RR vs. RQ/QQ; p = 0.96). In the subgroup of patients with FH no association was found among cardiovascular disease, genotype and FVII Ag levels (RR vs. RQ/QQ; p = 0.97).

Conclusions

Our study did not find a direct relationship between cardiovascular risk in patients with Heterozygous Familial Hypercholesterolemia, the R353Q polymorphism of factor VII and FVII Ag levels.

Genetic polymorphisms and atrial fibrillation: Insights into the prothrombotic state and thromboembolic risk

The pathophysiology of thromboembolism in atrial fibrillation (AF) is a multifactorial and complex process. Abnormalities of haemostasis, fibrinolysis, endothelium, and platelets have all been described in AF. This prothrombotic state observed in AF appears to be additive to the presence of clinical and echocardiography risk factors for thromboembolism. Nonetheless, the precise mechanistic pathway(s) leading to the prothrombotic state in AF remain to be elucidated. Of note, there are limited data on the influence of genetic polymorphisms in thromboembolic risk associated with AF. On the other hand, the response to coumarin derivatives depends on several factors, such as sex, age, diet, or interacting drugs. Optimal anticoagulation control is usually hampered by significant interindividual variability in dose requirements for a given target level of anticoagulation. There is increasing evidence that interindividual sensitivity and side-effects to coumarinics may be largely determined genetically. Thus, genetic polymorphisms could explain the individual risk of developing an adverse drug reaction (bleeding) or drug inefficacy (thrombosis) with oral anticoagulation. In this article, we provide an overview of the limited data about the possible influence of genetic polymorphisms on thromboembolic risk in AF, as well as the genetic influences on anticoagulant drug responsiveness.

Using a minigene approach to characterize a novel splice site mutation in human F7 gene causing inherited factor VII deficiency in a Chinese pedigree

Factor VII deficiency which transmitted as an autosomal recessive disorder is a rare haemorrhagic condition. The aim of this study was to identify the molecular genetic defect and determine its functional consequences in a Chinese pedigree with FVII deficiency. The proband was diagnosed as inherited coagulation FVII deficiency by reduced plasma levels of FVII activity (4.4%) and antigen (38.5%). All nine exons and their flanking sequence of F7 gene were amplified by polymerase chain reaction (PCR) for the proband and the PCR products were directly sequenced. The compound heterozygous mutations of F7 (NM_000131.3) c.572-1G>A and F7 (NM_000131.3) c.1165T>G; p.Cys389Gly were identified in the proband's F7 gene. To investigate the splicing patterns associated with F7 c.572-1G>A, ectopic transcripts in leucocytes of the proband were analyzed. F7 minigenes, spanning from intron 4 to intron 7 and carrying either an A or a G at position -1 of intron 5, were constructed and transiently transfected into human embryonic kidney (HEK) 293T cells, followed by RT-PCR analysis. The aberrant transcripts from the F7 c.572-1G>A mutant allele were not detected by ectopic transcription study. Sequencing of the RT-PCR products from the mutant transfectant demonstrated the production of an erroneously spliced mRNA with exon 6 skipping, whereas a normal splicing occurred in the wide type transfectant. The aberrant mRNA produced from the F7 c.572-1G>A mutant allele is responsible for the factor VII deficiency in this pedigree.

Major differences in bleeding symptoms between factor VII deficiency and hemophilia B

SUMMARY BACKGROUND

The autosomally-inherited factor VII (FVII) deficiency and X-linked hemophilia B offer an attractive model to investigate whether reduced levels of FVII and FIX, acting in the initiation and amplification of coagulation respectively, influence hemostasis to a different extent in relation to age and bleeding site.

METHODS

Hemophilia B patients (n = 296) and FVII-deficient males (n = 109) were compared for FVII/FIX clotting activity, F7/F9 genotypes and clinical phenotypes in a retrospective, multi-centre, cohort study.

RESULTS

Major clinical differences between diseases were observed. Bleeding occurred earlier in hemophilia B (median age 2.0 years, IR 0.9-5.0) than in FVII deficiency (5.2 years, IR 1.9-15.5) and the bleeding-free survival in FVII deficiency was similar to that observed in 'mild' hemophilia B (P = 0.96). The most frequent disease-presenting symptoms in hemophilia B (hematomas and oral bleeding) differed from those in FVII deficiency (epistaxis and central nervous system bleeding). Differences were confirmed by analysis of FVII-deficient women.

CONCLUSIONS

Our data support the notion that low FVII levels sustain hemostasis better than similarly reduced FIX levels. On the other hand, minute amounts of FVII, differently to FIX, are needed to prevent fatal bleeding, as indicated by the rarity of null mutations and the associated life-threatening symptoms in FVII deficiency, which contributes towards shaping clinical differences between diseases in the lowest factor level range. Differences between diseases are only partially explained by mutational patterns and could pertain to the specific roles of FVII and FIX in coagulation phases and to vascular bed-specific components.

Effective Hemostasis During Minor Surgery in a Case of Hereditary Combined Deficiency of Vitamin K-dependent Clotting Factors

Combined deficiency of the vitamin K-dependent clotting factors (VKCFD) is a rare bleeding disorder involving defective gamma-carboxylation of coagulation factors II , VII, IX and X as well as natural anticoagulants protein C and protein S. The disease is characterized by a cluster of different, often life threatening, bleeding symptoms occurring both spontaneously and in a surgical setting. In the present paper we describe two different treatment modalities to be used both in a programmed surgical procedure and in an emergency scenario. As this disease is a natural model that resembles oral anticoagulation, our experience discloses a possible rationale in the use of recombinant activated FVII for warfarin reversal.

Reduced factor VII and factor VIII levels and prolonged thrombin-generation times during a healthy diet in middle-aged women with mild to moderate cardiovascular disease risk

BACKGROUND

No experimental study has investigated the effect of whole-diet therapies on a wide range of hemostatic parameters, and their relationship with metabolic and inflammatory markers. Such information was sought in middle-aged women with moderate cardiovascular disease (CVD) risk subjected to an integrated healthy diet.

METHODS

Forty-nine premenopausal women were screened for C-reactive protein levels > or =1 mg L(-1) and at least one additional CVD risk factor. Sixteen women (age: 43-54 years) were selected and received a 12-week diet (four phases) integrating National Cholesterol Education Program-Adult Treatment Panel-III recommendations with components of a Mediterranean-style diet.

RESULTS

We observed a reduction in body mass index (BMI) (P = 0.001), waist circumference (P = 0.005), total (P = 0.011) and low-density lipoprotein (LDL) cholesterol levels (P = 0.035). Antigen levels of coagulation factor (F)VII (P = 0.003) and FVIII (P = 0.005) were clearly reduced by dietary intervention, which also appeared to decrease circulating tissue factor but not fibrinogen and von Willebrand factor (VWF) antigen levels. Levels of FVIII and tumor necrosis factor-alpha, among the inflammation markers, showed the highest correlation, particularly before the intervention (r = 0.55, P = 0.032). Only this cytokine influenced FVIII variation over time, thus highlighting new relations between coagulation and cellular components of inflammation. The functional effect of diet on coagulation was indicated by markedly prolonged thrombin generation initiation and propagation times (lag time, P = 0.002; time to peak, P = 0.005).

CONCLUSIONS

The changes observed in coagulation initiation and amplification phases, body composition and lipid profile could translate into a remarkable decrease in the risk for cardiovascular disease. Our observations suggest novel relationships between coagulation and inflammatory components.

Vitamin K-induced modification of coagulation phenotype in VKORC1 homozygous deficiency

BACKGROUND

Combined vitamin K-dependent clotting factor (VKCF) deficiency type 2 (VKCFD2) is a rare bleeding disorder caused by mutated vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) gene.

METHODS AND RESULTS

An Italian patient with moderate to severe bleeding tendency was genotyped, and found to be homozygous for the unique VKORC1 mutation (Arg98Trp) so far detected in VKCFD2. The activity levels of VKCFs were differentially reduced, and inversely related to the previously estimated affinity of procoagulant factor propeptides for the gamma-carboxylase. The normal (factor IX) or reduced antigen levels (other VKCFs) produced a gradient in specific activities. Vitamin K supplementations resulted in reproducible, fast and sustained normalization of PT and APTT. At 24 h the activity/antigen ratios of VKCFs were close to normal, and activity levels were completely (factor VII and IX), virtually (prothrombin, factor X and protein C) or partially (protein S) restored. Thrombin generation assays showed a markedly shortened lag time. The time to peak observed at low tissue factor concentration, potentially mimicking the physiological trigger and able to highlight the effect of reduced protein S levels, was shorter than that in pooled normal plasma. At 72 h the thrombin generation times were normal, and the decrease in activity of procoagulant VKCFs was inversely related to their half-life in plasma. The improved coagulation phenotype permitted the uneventful clinical course after invasive diagnostic procedures.

CONCLUSIONS

Modification of coagulation phenotypes in VKCFD2 after vitamin K supplementation was clinically beneficial, and provided valuable patterns of factor specific biosynthesis, half-life and decay.

Factor VII -323 decanucleotide D/I polymorphism in atrial fibrillation: implications for the prothrombotic state and stroke risk

There are limited data on the influence of genetic polymorphisms in atrial fibrillation (AF) stroke risk. We hypothesized that a functional haemostatic polymorphism, that is, the factor VII -323 Del/Ins polymorphism, would influence the prothrombotic state associated with AF, as well as stroke risk. Other functional polymorphisms were also tested.

METHODS

We performed a cross-sectional study of 119 AF patients, who were compared to 96 patients with stroke secondary to AF. In the first patient group, we analysed plasma prothrombin fragment 1+2 levels (F1+2, an index of thrombin generation) to reflect the prothrombotic state of AF.

RESULTS

AF patients carrying the -323 Ins allele had lower plasma F1+2 levels (P=0.015). After multivariate analysis adjusted by age, sex and clinical risk factors, advanced age and 807C/T polymorphism of glycoprotein Ia (GPIa) gene were associated with higher risk of ischaemic stroke (OR: 1.06; P=0.003 and OR: 1.91; P=0.025), whilst FVII Ins -323 allele was associated with lower stroke risk (OR: 0.41; P=0.017).

CONCLUSION

FVII -323 Ins allele may modulate the prothrombotic state associated with AF. Despite the small sample size, we found that FVII Ins -323 allele could be associated with a lower stroke risk in AF, whereas the 807C/T polymorphism may increase the risk.

Coagulation factor VII and inflammatory markers in patients with coronary heart disease

To further elucidate the connection between inflammation and factor VII (FVII) taking genetic variation in the FVII locus into account, we have examined 387 patients after myocardial infarction and 387 age-matched and sex-matched healthy control individuals. Circulating levels of C-reactive protein, FVII antigen (FVIIag), activated FVII (FVIIa), fibrinogen and interleukin-6 were analysed and all subjects were genotyped for the Arg353Gln polymorphism in the FVII locus. Plasma concentrations of C-reactive protein, fibrinogen, and interleukin-6 were higher among patients than control individuals. FVIIag was lower in the patient group, but for FVIIa there was no difference between the two groups. Among the inflammatory markers, only C-reactive protein indicated a weak nonlinear association with FVII. No significant difference in frequency of the Gln allele was observed between patients and control individuals but the presence of the Gln allele was associated with lower plasma levels of FVIIag and FVIIa in both groups. The low-grade chronic inflammation seen 3 months after myocardial infarction is not of major importance for the variation in plasma concentration of FVII. The presence of the Gln allele in the Arg353Gln polymorphism in the FVII locus did not differ between patients and control individuals but was associated with lower plasma levels of FVIIag and FVIIa that could have a protective effect against myocardial infarction. To further elucidate these facts, a prospective study should be performed to reduce the risk of a possible selection bias due to coronary heart disease death seen in retrospective case-control studies.

Factor VII polymorphisms influence the plasma response to diets with different fat content, in a healthy Caucasian population

To determine the influence of the factor VII gene polymorphisms, R353Q and 5'F7, on factor VII Ag plasma levels after the consumption of diets with different fat contents.

METHODS

59 healthy individuals (42 RR, 16 RQ, 1 QQ at the R353Q and 46 A1A1, 13 A1A2 at the 5'F7) consumed 3 diets during 4-weeks each: a Saturated diet (SAT) enriched in saturated fatty acid (SFA) (38% fat, 20% SFA), followed by a carbohydrate (CHO)-rich diet (30% fat, 55% CHO) or a Mediterranean diet (MEDIT) enriched in monounsaturated fatty acid (MUFA) (38% fat, 22% MUFA) following a randomized crossover design. Plasma lipids and FVII Ag plasma levels were determined at the end of each dietary period.

RESULTS

After a SAT diet, RR homozygotes had greater concentrations of FVII Ag compared with MEDIT and CHO diets than did carriers of the minority Q allele (82.76 +/- 1.3 vs. 75.02 +/- 2.4, p = 0.001). The 5'F7 polymorphism behaved in a similar fashion (A1A1 81.98 +/- 1.4 vs. A1A2 75.37 +/- 2.4, p = 0.026).

CONCLUSIONS

Our data show that carriers of the RR and/or A1A1 genotype present higher FVII Ag levels after the consumption of a SAT diet compared with the MEDIT and CHO rich diets.

Molecular analysis in a patient with severe factor VII deficiency and an inhibitor: report of a novel mutation (S103G)

Congenital factor VII (FVII) deficiency is an autosomal recessive bleeding disorder with variable phenotypic correlation between FVII activity and bleeding risk. We report a novel mutation of the FVII gene that creates the amino acid change Ser 103 to Gly, which resulted in severe FVII deficiency with reduced FVII antigen. This mutation in the heterozygous form was also present in a mildly affected, unrelated patient. We also report on the natural history of an FVII inhibitor in the patient with severe FVII deficiency.

Postprandial factor VII metabolism: the effect of the R353Q and 10 bp polymorphisms

Elevated levels of coagulation factor VII activity (FVIIc) are associated with increased risk of CHD. FVIIc is strongly determined by two polymorphisms (R353Q and 0/10 base pairs (bp)) and plasma triacylglycerol (TAG) concentrations. The Q and 10 bp polymorphisms show strong linkage disequilibrium and have been associated with lower levels of fasting FVII, but there has been little investigation of the effect of these genotypes on the postprandial FVII metabolism. The present study demonstrated that fasting activated factor VII (FVIIa) and factor VII antigen (FVIIag) levels were significantly lower in the heterozygotes carrying the Q and 10 bp alleles (n12), than in the R/0 bp homozygotes (n12) (43·0 (SE 4·8)v. 23·9 (SE 6·5) mU/ml and 85·7 (SE 5·4)v. 71·6 (SE 7·5) % respectively). During postprandial lipaemia there was a significant increase in FVIIa in R/0 bp homozygotes but not in the heterozygotes carrying the Q and 10 bp alleles. The proportion of FVIIa (FVIIa : FVIIag) increased in the homozygotes but not in the heterozygotes (2·04 (SE 0·35)v. 1·20 (SE 0·26) respectively). Therefore possession of the relatively common Q and 10 bp alleles is not associated with postprandial activation of FVII, which may in turn have a protective effect against CHD.

Functional analysis of the genetic variability in the F7 gene promoter

The FVII level is considered a risk factor for cardiovascular disease. Some of the polymorphic differences in the promoter of the F7 gene have been associated with variations in FVII levels. However, linkage disequilibrium among those polymorphisms has made it difficult to pinpoint the true functional variants, so contradictory results have often appeared among various studies. We provide new findings of the effect of the polymorphisms in the promoter region of F7. In vitro transfection of 15 plasmids containing different combinations of F7 promoter polymorphisms was performed in HepG2 cells. We found that allelic variants -323ins10 and -122C strongly reduced promoter activity and that allelic variant -402A significantly increased promoter activity. We report the effect of a novel variant (-2989A) that significantly increases F7 expression levels. However, this novel allelic variant is in strong linkage disequilibrium with the -323ins10 variant in our Spanish population, which has a clear dominant effect over the -2989A variant and completely masks its effect. Our results have important implications for mapping genes affecting complex diseases using association studies. That is, they imply that true functional variants should be chosen to confirm the analyses and to ensure that the results can be reproduced in other populations. In addition, our results suggest that it would be informative to screen for the -2989A variant in other populations, since it may well be a risk factor for cardiovascular disease in populations where it does not appear with the decanucleotide insertion.

Tissue Factor and Coagulation Factor VII Levels During Acute Myocardial Infarction

Objective— We investigated in patients with ongoing myocardial infarction (MI) whether coagulation factor VII (FVII) and tissue factor (TF) levels are affected at admission by genetic components and whether they may predict subsequent cardiovascular events.

Methods and Results— 256 patients admitted for MI were evaluated for FVII and TF antigen levels before any treatment at entry, and were genotyped for FVII and TF polymorphisms. FVII gene insertions at −323, 11293 and the −402G/A change predicted FVII levels and explained 14% of variance. The −603 TF gene polymorphism failed to affect significantly TF levels ( P =0.07). These variables were correlated with the incidence of death (36 patients) and reinfarction (9 patients) after a median follow-up of 397 days. Events were independently predicted by FVII (HR 2.1, 95% CI 1.2 to 5.7) and TF (HR 4.1, 95% CI 2 to 11) levels. Composite end point was significantly worse when both parameters were above the receiver-operating characteristics (ROC) values (HR 8.3, 95% CI 5 to 18, compared with FVII and TF below), and above the ROC value of TF (>630 pg/mL) it differed among FVII genotype groups.

Conclusions— Admission FVII and TF antigen levels, partially predicted by polymorphisms, are independent predictors of mortality and reinfarction in patients with acute MI.

The Effects of Three Factor VII Polymorphisms on Factor VII Coagulant Levels in Healthy Singaporean Chinese, Malay and Indian Newborns

Factor VII (FVII) is an independent risk factor for coronary artery disease. Three polymorphisms of the factor VII gene (F7) were studied in a group of healthy newborns comprising 561 Chinese, 398 Malays and 226 Asian Indians from Singapore. The allele frequencies of 3 polymorphisms (R353Q, Promoter 0/10bp Del/Ins and Intron 7) in the FVII gene were ascertained through genotyping by polymerase chain reaction and restriction digestion of amplified fragments. In Chinese the minor allele frequencies are Q: 0.04, Ins: 0.03, R7: 0.44; Malays, Q: 0.06, Ins: 0.10, R7: 0.41; and Indians, Q: 0.25, Ins: 0.23, R7: 0.43. Strong linkage disequilibrium (Delta > 0.7) is observed between the 0/10 bp and the R353Q sites in all ethnic groups. We conclude that: (i) the prevalence of the minor Q and Ins alleles of the R353Q and 0/10 bp polymorphisms are significantly higher in the Indian newborns than the Chinese and Malays; (ii) the Q allele is significantly associated (p = 0.01) with a lower plasma FVII coagulant level in the Indian and Malay neonates; and this polymorphism explains up to 3.8% of the variance in FVII coagulant levels; (iii) there is no significant difference in allele frequencies of the three polymorphisms between neonates with and without family histories of CAD.

Genetic architecture of the F7 gene in a Spanish population: implication for mapping complex diseases and for functional assays

Delineating the genetic variability of loci coding for complex diseases helps to understand the individual variation in disease susceptibility and drug response. We present the allelic architecture of the F7 gene. This gene is the major determinant of FVII plasma levels, and these plasma levels constitute an important intermediate risk factor for cardiovascular disease. As part of the Genetic Analysis of Idiopathic Thrombophila Project, we completely re-sequenced the F7 locus (promoter, exons, introns, and 3'-untranslated region) in 40 unrelated individuals. We found 49 polymorphisms with only two amino acid changes suggesting that regulatory non-coding and intronic variants are responsible for the FVII variability. These results are important for mapping susceptibility alleles of complex diseases, because differences in pair-wise linkage disequilibrium patterns between DNA variants and haplotype frequency distributions may help to detect disease-associated alleles. In addition, we present the results of an in silico search that established genomic comparisons among different species. In conclusion, our study of the F7 DNA sequence variations is an example of a strategy for analyzing the genetic architecture of a quantitative trait locus. Furthermore, it provides a model for future analyses of genetic factors that contribute to the susceptibility of complex diseases in humans.

Factor VII Gene Haplotypes and Risk of Ischemic Stroke

Background: Coagulation factor VII (FVII) plays an important role in the activation of blood coagulation and clot formation. Recent studies have provided evidence for an association between common polymorphic markers in the FVII gene and plasma FVII concentrations. The 353R&gt;Q sequence variation, and 3 common sequence variations in the promoter of the FVII gene—the 10-bp insertion/deletion at position −323 and the −401G&gt;T and −402G&gt;A sequence variations—are well-known determinants of circulating FVII concentrations.

Methods: To clarify the role of these sequence variations in the pathogenesis of ischemic stroke, we performed a case–control study with 242 patients with ischemic stroke before the age of 60 years and 239 healthy controls.

Results: The −323 insertion/deletion and the 353R&gt;Q and −401G&gt;T sequence variations were in strong linkage disequilibrium, and the resulting haplotypes occurred with equal frequencies in patients and controls. The variant form of FVII (−402G&gt;A) occurred only in combination with the common (wild-type) sequences at all other loci. This haplotype was more frequent in patients than in healthy controls (28% vs 22%). The difference in the prevalence of carriers of this haplotype among patients and controls was statistically significant (P = 0.03; odds ratio = 1.6; 95% confidence interval, 1.1–2.6).

Conclusion: According to our results, the FVII −402A allele seems to increase the risk of early ischemic cerebrovascular events, whereas the 353R&gt;Q, G−401T, and −323ins/del sequence variations, which are in close linkage disequilibrium, apparently do not influence the risk of stroke.

Common Genetic Variation in Five Thrombosis Genes and Relations to Plasma Hemostatic Protein Level and Cardiovascular Disease Risk

OBJECTIVE

We undertook a linkage disequilibrium (LD)-based genetic approach to investigate the hypothesis that common sequence variants in 5 thrombosis genes influence plasma hemostatic protein levels or risk of cardiovascular disease (CVD).

METHODS AND RESULTS

In a reference panel, we characterized LD structure at the fibrinogen gene cluster (fibrinogen-beta[FGB], FGA, and FGG), factor VII (F7), and tissue plasminogen activator (PLAT) loci. Forty-one tag single nucleotide polymorphisms (SNPs) were genotyped in 1811 unrelated Framingham Heart Study participants. There were significant associations of 9 FGB SNPs with fibrinogen level (minimum P=0.002) and of 7 F7 SNPs and factor VII level (minimum P<0.0001). SNPs at the PLAT locus were not associated with PLAT level. In stepwise analysis, a single FGB variant explained 1% of the residual variance in fibrinogen level, and 2 F7 SNPs together explained 10% of the residual variance in factor VII level. Two PLAT haplotypes were associated with CVD (multivariable-adjusted global P=0.0004).

CONCLUSIONS

A comprehensive survey of common sequence variation demonstrates that cis-regulatory SNPs explain a modest proportion of the residual variance in circulating fibrinogen and factor VII level and PLAT haplotypes increase the risk of CVD. Additional studies are warranted to confirm the association of PLAT sequence variation and risk of CVD.

Genetic influence on thrombotic risk markers in the elderly--a Danish twin study

OBJECTIVE

Several hemostatic variables are identified as cardiovascular risk markers. In young and middle-aged individuals, plasma concentrations of these variables are partly determined by genetic factors. The genetic contribution to cardiovascular disease (CVD) decreases with increasing age, and it is therefore important to determine the heritability of hemostasis also in the elderly.

METHODS

The heritability of plasma levels of factor VII, fibrinogen, tissue factor, tissue factor pathway inhibitor, von Willebrand factor, thrombin activatable fibrinolysis inhibitor (TAFI), and D-dimer was determined in 130 monozygotic and 155 dizygotic same-sex twin pairs, aged 73-94 years, who participated in the Longitudinal Study of Aging of Danish Twins. Furthermore, we determined the influence of promoter polymorphisms in corresponding genes on the plasma level variation.

RESULTS

Genetic factors accounted for 33% (D-dimer) to 71% (TAFI) of the variation in plasma levels. Polymorphisms were associated with concentrations of FVII and TAFI in sib-pair based analyses, but in linkage analyses the polymorphisms did not explain a significant part of the genetic variation for any of the variables.

CONCLUSIONS

Concentrations of hemostatic variables have a substantial genetic variation in the elderly, but in this study the promoter polymorphisms only explained a minimal part of this variation.

Sequence variations within the genes related to hemostatic imbalance and their impact on coronary artery disease in Turkish population

Coronary artery disease (CAD) is reported to be associated with some genetic risk factors. Since identification of genetic risk factors for CAD in different ethnic groups is important for the development of new intervention and prevention programs, we investigated the association between the R353Q and -323ins10 polymorphisms in Factor VII gene, C677T mutation in MTHFR, Factor V Leiden and PT G20210A mutations and CAD in Turkish population. The promoter region of the PAI-1 gene was also screened by SSCA (single-stranded conformation analysis) using specifically designed primers. 137 CAD patients with early onset documented by coronary angiography and 41 individuals who had no significant coronary stenosis by angiography as control group were screened for the identification of the polymorphisms. In conclusion, Factor V Leiden was found to be an independent genetic risk factor for CAD in Turkish population. Combined risk assessment indicated that the coexistence of two other inherited thrombophilia markers, namely MTHFR C677T and PT G20210A with Factor V Leiden may increase the risk of the development of the disease in this population. The results of the present study show that there is no statistically significant association between the two polymorphisms in Factor VII gene, MTHFR C677T polymorphism, PT G20210A polymorphism, 4G/5G polymorphism of PAI-1 and CAD in Turkish population.

Human F7 sequence is split into three deep clades that are related to FVII plasma levels

It is widely accepted that FVII levels are strongly, consistently, and independently related to cardiovascular risk. These levels are influenced by genetic and environmental factors. Among the genetic factors, only a limited number of polymorphisms in the F7 gene have been reported, and they explain only a small proportion of the genetic variability. Recently, we have accomplished the complete dissection of the F7 quantitative trait locus responsible for all of the genetic variability observed in FVII levels. Now, we present the thorough study of the haplotype organization of F7 DNA sequence variation among individuals and the evolutionary processes that produced this variation, by sequencing 15 kb of genomic DNA sequence from the F7 locus in 40 unrelated individual (80 chromosomes) from the genetic analysis of idiopathic thrombophilia (GAIT) project as well as four non-human primate species. Our study revealed 49 polymorphisms, of which 39 SNPs were further considered. Genotyping of these DNA variations in the whole family-based GAIT sample helped resolve linkage phases, and a total of 37 distinct haplotypes were identified.Tajima's D was significantly positive in this sample, suggesting balancing selection. This parameter was a reflection of the phylogenetic structure of F7 haplotype, which was deeply split into three well-supported clades or haplogroups, suggesting that functional differences among F7 variants do not depend on a few single-site variations. Moreover, haplogroup 2 was associated with high FVII levels and haplogroup 3 with low levels. In this study, we have for the first time established a clear relation between genotypic variability structure and phenotypic variability of a particular quantitative trait involved in a complex disease.

Prolonged prothrombin time, Factor VII and activated FVII levels in chronic liver disease are partly dependent on Factor VII gene polymorphisms

BACKGROUND

Prothrombin time is a benchmark for functional assessment in cirrhosis and Factor VII levels (FVII), crucial in determining the prothrombin time, are genetically determined.

METHODS

We have evaluated the prothrombin time, a number of haemostatic variables synthesised by the liver (FII, FV, FVII and activated FVII, AT and fibrinogen) and two polymorphisms of the FVII gene (5'F7 and 353R/Q) in: (a) patients with liver cirrhosis (n=118), (b) patients with chronic hepatitis (n=102) and (c) controls (n=100).

RESULTS

By one-way analyses of variance, the prothrombin time and the mean levels of the FII, FV, FVIIc, FVIIa, and AT were statistically different between cirrhotics, chronic hepatitis patients and controls. The allele frequency of the FVII polymorphisms did not differ between the three groups. Those rare patients (4.6%) who were homozygous for the type 2 alleles had markedly reduced FVIIc and FVIIa levels. The analysis carried out taking into account Child class versus FVII genotype showed that the mean FVIIc levels were comparable for different genotypes within each Child's class, with the exception of the patients homozygous for the type 1 allele.

CONCLUSION

Our findings help to explain the not infrequent finding of a severely prolonged prothrombin time in patients who are otherwise in a good functional class.

Reduction in coagulation factor VII plasma levels by R353Q but not the -323P0/10 promoter polymorphism in healthy Tunisians

The association between the R353Q and -323P0/10 (10-bp insertion in the promoter region at position -323) factor VII mutations and plasma factor VII levels was investigated in a group of 214 healthy Tunisians. The frequency for the Q allele was 0.253 and that for the 10-bp allele was 0.206, and their distribution was variable, with a high prevalence of the 10-bp allele (0.306) seen in North Tunisia and a high prevalence of the Q allele (0.288) see in the Sahel region. No significant linkage disequilibrium was observed between the two mutations, and the most prevalent haplotype was -323P0/353R (0.589 +/- 0.054). Carriers of the R353Q (P < 0.001), but not -323P0/10 (P = 0.088), factor VII mutations had lower mean factor VII serum concentrations. This reduction in mean serum factor VII was more pronounced among homozygous (Q/Q) carriers and among males (49.9%) compared to females (32.7%). Adjusting for all other variables in the linear regression analysis (sex, age, region, smoking, and R353Q and -323P0/10 mutations), heterozygous carriers of the -323P0/10 and R353Q mutation had on average reductions of 10 units (P = 0.005) and 30 units (P < 0.001) in plasma factor VII, respectively, compared to noncarriers, while homozygote carriers of the R353Q (-43.3, P < 0.001), but not carriers of the -323P0/10 (-6.30, P = 0.356), had significantly lower levels of mean plasma factor VII. These data suggest that part of the previously described effects on FVIIc levels associated with the R/Q polymorphism may be explained by genetic variation in the promoter region of the FVII gene.

Population genetic and phylogenetic evidence for positive selection on regulatory mutations at the factor VII locus in humans

The abundance of cis-regulatory polymorphisms in humans suggests that many may have been important in human evolution, but evidence for their role is relatively rare. Four common polymorphisms in the 5' promoter region of factor VII (F7), a coagulation factor, have been shown to affect its transcription and protein abundance both in vitro and in vivo. Three of these polymorphisms have low-frequency alleles that decrease expression of F7 and may provide protection against myocardial infarction (heart attacks). The fourth polymorphism has a minor allele that increases the level of transcription. To look for evidence of natural selection on the cis-regulatory variants flanking F7, we genotyped three of the polymorphisms in six Old World populations for which we also have data from a group of putatively neutral SNPs. Our population genetic analysis shows evidence for selection within humans; surprisingly, the strongest evidence is due to a large increase in frequency of the high-expression variant in Singaporean Chinese. Further characterization of a Japanese population shows that at least part of the increase in frequency of the high-expression allele is found in other East Asian populations. In addition, to examine interspecific patterns of selection we sequenced the homologous 5' noncoding region in chimpanzees, bonobos, a gorilla, an orangutan, and a baboon. Analysis of these data reveals an excess of fixed differences within transcription factor binding sites along the human lineage. Our results thus further support the hypothesis that regulatory mutations have been important in human evolution.

Regulatory polymorphisms underlying complex disease traits

There is growing evidence that genetic variation plays an important role in the determination of individual susceptibility to complex disease traits. In contrast to coding sequence polymorphisms, where the consequences of non-synonymous variation may be resolved at the level of the protein phenotype, defining specific functional regulatory polymorphisms has proved problematic. This has arisen for a number of reasons, including difficulties with fine mapping due to linkage disequilibrium, together with a paucity of experimental tools to resolve the effects of non-coding sequence variation on gene expression. Recent studies have shown that variation in gene expression is heritable and can be mapped as a quantitative trait. Allele-specific effects on gene expression appear relatively common, typically of modest magnitude and context specific. The role of regulatory polymorphisms in determining susceptibility to a number of complex disease traits is discussed, including variation at the VNTR of INS, encoding insulin, in type 1 diabetes and polymorphism of CTLA4, encoding cytotoxic T lymphocyte antigen, in autoimmune disease. Examples where regulatory polymorphisms have been found to play a role in mongenic traits such as factor VII deficiency are discussed, and contrasted with those polymorphisms associated with ischaemic heart disease at the same gene locus. Molecular mechanisms operating in an allele-specific manner at the level of transcription are illustrated, with examples including the role of Duffy binding protein in malaria. The difficulty of resolving specific functional regulatory variants arising from linkage disequilibrium is demonstrated using a number of examples including polymorphism of CCR5, encoding CC chemokine receptor 5, and HIV-1 infection. The importance of understanding haplotypic structure to the design and interpretation of functional assays of putative regulatory variation is highlighted, together with discussion of the strategic use of experimental tools to resolve regulatory polymorphisms at a transcriptional level. A number of examples are discussed including work on the TNF locus which demonstrate biological and experimental context specificity. Regulatory variation may also operate at other levels of control of gene expression and the modulation of splicing at PTPRC, encoding protein tyrosine phosphatase receptor-type C, and of translational efficiency at F12, encoding factor XII, are discussed.

A case presenting concurrence of Marfan syndrome, Basedow's disease and Arg353Gln polymorphism-related factor VII deficiency

We report the case of a 48-year-old Japanese man who suffered from Marfan syndrome with severe aortic regurgitation, mitral regurgitation and rapid atrial fibrillation, which were aggravated by hyperdynamic circulatory conditions associated with coexistent Basedow's disease. Furthermore, concurrence of Arg353Gln polymorphism-related factor VII deficiency was discovered at the preoperative assessments. Both of his two brothers suffered from Marfan syndrome; however they had no findings of Arg353Glu polymorphism-related factor VII deficiency or Basedow's disease. After normalization of thyroid function, he had successfully the operations of Bentall procedure: a composite prosthetic graft: replacement of both the ascending aorta and aortic valve, and mitral valve annuloplasty. No specific therapy such as fresh frozen plasma or factor VII replacement therapy was required. He completely returned to his business work 6 weeks after the operation. Concurrence of Marfan syndrome and factor VII deficiency induced by two-hit genomic abnormalities and furthermore Basedow's disease, which significantly compromised the pathophysiological condition of Marfan syndrome, is extremely rare.

Inherited factor VII deficiency: identification of two novel mutations (A191V and T239P) in the catalytic domain

We describe here five F7 mutations found in four patients without bleeding history, despite constitutional coagulation Factor VII (FVII) deficiency. All five mutations are missense and affect the catalytic domain of FVII (A191T, A191V, T239P, R224Q and M298I). The A191V and T239P mutations are novel and were found in homozygous patients with no clinical bleeding tendency. The patient diagnosed with the A191V mutation had a phenotype corresponding to a moderate type 1 FVII deficiency (FVII:C 4%, FVII:Ag 5%). The T239P mutation was found in a patient with mild type 2 FVII deficiency (FVII:C 25%, FVII:Ag 95%). Novel mutations are both in close vicinity to the charge-stabilizing system of FVII. Modeling studies allow understanding in part the molecular basis for the loss of function.