Polymorphisms in the factor VII gene and the risk of myocardial infarction in patients with coronary artery disease

Association of congenital cardiovascular malformations with 33 single nucleotide polymorphisms of selected cardiovascular disease-related genes

INTRODUCTION

Clark (1996) proposed that abnormal blood flow is related to some congenital cardiovascular malformations (CCVMs), particularly CCVM with obstruction to blood flow. Our hypothesis is that CCVMs may relate to genes that affect blood coagulation or flow. We studied whether polymorphisms of such genes are related to CCVMs; previous association of these SNPs to conotruncal CCVMs is described.

METHODS

We assessed risk of pulmonary stenosis (PS, N = 120), atrial septal defect (ASD, N = 108), aortic stenosis (AS, N = 36), and coarctation of the aorta (CoAo, N = 64), associated with 33 candidate genes, selected for their relationship to blood flow affected by homocysteine metabolism, coagulation, cell-cell interaction, inflammation, or blood pressure regulation.

RESULTS

Effects were specific to cardiac phenotype and race. CoAo was associated with MTHFR (-667) C>T (odds ratio [OR] for TT 3.5, 95% confidence limits [CI] 1.4-8.6). AS was associated with a polymorphism of SERPINE1, G5>G4, OR = 5.6 for the homozygote with 95% CI 1.4-22.9. Unique polymorphisms were associated with increased risk of ASD and PS: NPPA 664G>A with ASD (OR of 2.4, 95%CI 1.3-4.4) and NOS3 (-690) C>T with PS (OR 6.1; 95% CI 1.6-22.6 in the African American population only). For ASD, the NPPA (-664) G>A SNP there was increased risk from the variant genotype only in maternal smokers (OR 2.6; 95% CI 1.0-7.2).

CONCLUSIONS

Genes affecting vascular function and coagulation appear to be promising candidates for the etiology of cardiac malformations and warrant further study.

Novel associations of multiple genetic loci with plasma levels of factor VII, factor VIII, and von Willebrand factor: The CHARGE (Cohorts for Heart and Aging Research in Genome Epidemiology) Consortium

BACKGROUND

Plasma levels of coagulation factors VII (FVII), VIII (FVIII), and von Willebrand factor (vWF) influence risk of hemorrhage and thrombosis. We conducted genome-wide association studies to identify new loci associated with plasma levels.

METHODS AND RESULTS

The setting of the study included 5 community-based studies for discovery comprising 23 608 European-ancestry participants: Atherosclerosis Risk In Communities Study, Cardiovascular Health Study, British 1958 Birth Cohort, Framingham Heart Study, and Rotterdam Study. All subjects had genome-wide single-nucleotide polymorphism (SNP) scans and at least 1 phenotype measured: FVII activity/antigen, FVIII activity, and vWF antigen. Each study used its genotype data to impute to HapMap SNPs and independently conducted association analyses of hemostasis measures using an additive genetic model. Study findings were combined by meta-analysis. Replication was conducted in 7604 participants not in the discovery cohort. For FVII, 305 SNPs exceeded the genome-wide significance threshold of 5.0x10(-8) and comprised 5 loci on 5 chromosomes: 2p23 (smallest P value 6.2x10(-24)), 4q25 (3.6x10(-12)), 11q12 (2.0x10(-10)), 13q34 (9.0x10(-259)), and 20q11.2 (5.7x10(-37)). Loci were within or near genes, including 4 new candidate genes and F7 (13q34). For vWF, 400 SNPs exceeded the threshold and marked 8 loci on 6 chromosomes: 6q24 (1.2x10(-22)), 8p21 (1.3x10(-16)), 9q34 (<5.0x10(-324)), 12p13 (1.7x10(-32)), 12q23 (7.3x10(-10)), 12q24.3 (3.8x10(-11)), 14q32 (2.3x10(-10)), and 19p13.2 (1.3x10(-9)). All loci were within genes, including 6 new candidate genes, as well as ABO (9q34) and VWF (12p13). For FVIII, 5 loci were identified and overlapped vWF findings. Nine of the 10 new findings were replicated.

CONCLUSIONS

New genetic associations were discovered outside previously known biological pathways and may point to novel prevention and treatment targets of hemostasis disorders.

Boy with pseudohypoparathyroidism type 1a caused by GNAS gene mutation (deltaN377), Crouzon-like craniosynostosis, and severe trauma-induced bleeding

We report on a 6-month-old boy with craniosynostosis, pseudohypoparathyroidism type 1a (PHP1A), and a GNAS gene mutation. He had synostoses of the coronal, frontal, and sagittal sutures, brachyturricephaly, and hydrocephaly. He also had congenital hypothyroidism, round face, full cheeks, shortness of limbs, mild developmental delay, and muscular hypotonia. Because of progressive hydrocephaly, the synostosis was corrected surgically but circulatory decompensation led to disseminated intravascular coagulation and cerebral infarctions. Our patient died 8 days later. Postmortem molecular studies of GNAS, the gene for guanine nucleotide-binding protein, alpha-stimulating activity polypeptide (gene for PHP1A), identified a de novo heterozygous 3 bp in frame deletion predicting a deletion of the asparagine residue at position 377 (deltaN377). This is the second report of this mutation. Results of molecular studies of craniosynostosis genes (FGFR2, FGFR3) and of numerous genetic variants predisposing to bleeding disorders were normal. We question whether craniosynostosis and trauma-induced bleeding disorder may be manifestations of PHP1A, or if our patient had two or three different congenital disorders.

Clinical factors such as B-type natriuretic peptide link to factor VII, endothelial NO synthase and estrogen receptor alpha polymorphism in elderly women

AIMS

This study evaluated the presence of genetic mutations in relation to thrombosis or atherosclerosis in elderly women.

MAIN METHODS

This is an observational study of 93 Japanese women with a mean age of 80.9 years recruited from outpatient clinics of Nagoya University and its related hospitals. Ten single nucleotide polymorphisms (SNPs) were studied. Each gene studied acts in or is related to either blood coagulation (factor V Leiden, prothrombin G20210A, factor XIII Val34Leu, factor VII Arg353Gln, MTHFR C677T, beta-fibrinogen G-455A, PAI-1 4G/5G), metabolic syndrome-related pathways (PPARalpha Leu162Val), or endothelium/estrogen system (eNOS Glu298Asp, ERalpha IVS1-401). SNPs were analyzed for their relation to clinical values including lipids, B-type natriuretic peptide (BNP), fasting plasma glucose, tumor necrosis factor-alpha, interleukin-6, cyclic GMP, and nitric oxide metabolites.

KEY FINDINGS

Comparisons between the distributions of different genotypes and clinical values showed three relationships. First, factor VII Arg353Gln and HDL-cholesterol (HDL-C) were linked to Arg/Arg carriers at higher levels (P=.049). The HDL-C to LDL-cholesterol ratio supported this link (P=.027). Second, eNOS Glu298Asp and triglycerides were linked to Glu/Glu carriers at higher levels (P=.031). Third, ERalpha IVS1-401 and BNP were related to CC genotype at lower levels (P=.031). Additionally, the last two relations showed that genotype does not influence the demarcation line of biomarkers, but the plasma/serum levels of biomarkers instead.

SIGNIFICANCE

Correlations of factor VII Arg353Gln with HDL-C and eNOS Glu298Asp with triglycerides are new findings. Polymorphisms in the endothelium/estrogen system and the heart failure marker BNP are also correlated, with ERalpha IVS1-401 being the first identified marker. SNPs may be helpful for understanding the pathophysiology of atherosclerotic diseases in elderly women.

Novel serum paraoxonase activity assays are associated with coronary artery disease

BACKGROUND

Serum paraoxonase (PON1) exerts antiatherogenic effects. Novel PON1 enzymatic tests have been recently developed: 5-thiobutyl butyrolactone (TBBL) estimates PON1 lactonase activity, whereas 7-O-diethylphosphoryl-3-cyano-4-methyl-7-hydroxycoumarin (DEPCyMC) is considered a surrogate marker of PON1 concentration. The TBBL to DEPCyMC ratio provides the normalized lactonase activity (NLA), which may reflect the degree of PON1 lactonase catalytic stimulation. The aim of this study was to evaluate for the first time TBBLase and DEPCyMCase activity in patients with coronary artery disease (CAD).

METHODS

An angiography-based case-control study was conducted, including 300 sex- and age-matched subjects [100 CAD-free, 100 CAD without myocardial infarction (MI) and 100 CAD with MI].

RESULTS

A low DEPCyMCase activity (lowest vs. highest tertile: OR 2.96, 95% CI 1.18-7.43) and a high NLA (highest vs. lowest tertile: OR 3.25, 95% CI 1.28-8.26) were both associated with CAD, independent of classical atherosclerosis risk factors, lipid-lowering therapy and PON1 genotype. Total TBBLase activity was, however, not different in CAD compared to CAD-free subjects.

CONCLUSIONS

Novel PON1 activity assays may be associated with CAD. In this study, CAD patients had low DEPCyMCase activity, a possible marker of low PON1 concentration, but showed a high stimulation of PON1 lactonase activity.

Additive effect of LRP8/APOER2 R952Q variant to APOE epsilon2/epsilon3/epsilon4 genotype in modulating apolipoprotein E concentration and the risk of myocardial infarction: a case-control study

BACKGROUND

The R952Q variant in the low density lipoprotein receptor-related protein 8 (LRP8)/apolipoprotein E receptor 2 (ApoER2) gene has been recently associated with familial and premature myocardial infarction (MI) by means of genome-wide linkage scan/association studies. We were interested in the possible interaction of the R952Q variant with another established cardiovascular genetic risk factor belonging to the same pathway, namely apolipoprotein E (APOE) epsilon2/epsilon3/epsilon4 genotype, in modulating apolipoprotein E (ApoE) plasma levels and risk of MI.

METHODS

In the Italian cohort used to confirm the association of the R952Q variant with MI, we assessed lipid profile, apolipoprotein concentrations, and APOE epsilon2/epsilon3/epsilon4 genotype. Complete data were available for a total of 681 subjects in a case-control setting (287 controls and 394 patients with MI).

RESULTS

Plasma ApoE levels decreased progressively across R952Q genotypes (mean levels +/- SD = RR: 0.045 +/- 0.020, RQ: 0.044 +/- 0.014, QQ: 0.040 +/- 0.008 g/l; P for trend = 0.047). Combination with APOE genotypes revealed an additive effect on ApoE levels, with the highest level observed in RR/non-carriers of the E4 allele (0.046 +/- 0.021 g/l), and the lowest level in QQ/E4 carriers (0.035 +/- 0.009 g/l; P for trend = 0.010). QQ/E4 was also the combined genotype with the most significant association with MI (OR 3.88 with 95%CI 1.08-13.9 as compared with RR/non-carriers E4).

CONCLUSION

Our data suggest that LRP8 R952Q variant may have an additive effect to APOE epsilon2/epsilon3/epsilon4 genotype in determining ApoE concentrations and risk of MI in an Italian population.

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.

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.

Inherited Thrombophilia

Inherited thrombophilia can be defined as a genetically determined predisposition to the development of thromboembolic complications. Since the discovery of activated protein C resistance in 1993, several additional disorders have been described and, at present, it is possible to identify an inherited predisposition in about 60 to 70% of patients with such complications. These inherited prothrombotic risk factors include qualitative or quantitative defects of coagulation factor inhibitors, increased levels or function of coagulation factors, defects of the fibrinolytic system, altered platelet function, and hyperhomocysteinemia. In this review, the main inherited prothrombotic risk factors are analyzed from epidemiological, laboratory, clinical, and therapeutic points of view. Finally, we discuss the synergism between genetic and acquired prothrombotic risk factors in particular conditions such as childhood and pregnancy.

FADS genotypes and desaturase activity estimated by the ratio of arachidonic acid to linoleic acid are associated with inflammation and coronary artery disease

BACKGROUND

The delta-5 and delta-6 desaturases, encoded by FADS1 and FADS2 genes, are key enzymes in polyunsaturated fatty acid (PUFA) metabolism that catalyze the conversion of linoleic acid (LA) into arachidonic acid (AA) and that of alpha-linolenic acid (ALA) into eicosapentaenoic acid (EPA). Single-nucleotide polymorphisms (SNPs) in FADS1 and FADS2 have been associated with different concentrations of AA and LA, and those associations have possible functional consequences for desaturase activity.

OBJECTIVE

We aimed to evaluate the possible association among FADS genotypes, desaturase activity, inflammation, and coronary artery disease (CAD).

DESIGN

Thirteen FADS SNPs and the ratio of AA to LA (AA/LA) on red blood cell (RBC) membranes, a marker of desaturase activity, were evaluated in 876 subjects with (n = 610) or without (n = 266) angiographically documented CAD.

RESULTS

Both AA/LA and the ratio of EPA to ALA (EPA/ALA) were higher in patients with CAD than in those without CAD, but, in a multiple logistic regression model, only a higher AA/LA resulted an independent risk factor for CAD (odds ratio: 2.55; 95% CI: 1.61, 4.05 for higher compared with lower ratio tertile; P for trend < 0.001). Furthermore, concentrations of high-sensitivity C-reactive protein increased progressively across tertiles of AA/LA. Graded increases in high-sensitivity C-reactive protein concentrations and CAD risk were related to the carriership of FADS haplotypes, including the alleles associated with a higher ratio.

CONCLUSION

In populations following a Western diet, subjects carrying FADS haplotypes that are associated with higher desaturase activity may be prone to a proinflammatory response favoring atherosclerotic vascular damage.

Cardiovascular disease and heritability of the prothrombotic state

Atherothrombotic disease remains a major cause of mortality worldwide, and family clustering suggests an important contribution of genetic factors to disease pathogenesis. Thrombus formation represents the final step in atherothrombosis, a process influenced by genetic and environmental factors. A major difficulty of investigating the genetic regulation of thrombotic conditions is the complexity of the phenotype and the relatively modest effects of individual genetic variations. We address in this review genetic aspects involved in regulating thrombosis potential and their impact on the development of atherothrombotic disease. The effects of common genetic polymorphisms in clotting factors are discussed and examples of complex gene-gene and gene-environment interactions are highlighted. Understanding the effects of genetic factors on predisposition to thrombotic disease and unravelling the complex gene-environment interactions will help to better understand the pathophysiology of this complex condition, which will enable the development of new preventative and treatment strategies.

Polymorphisms in coagulation factors and the risk of recurrent cardiovascular events in men after a first myocardial infarction

BACKGROUND

The aim of this study was to examine whether genetic predisposition to high levels of coagulation factors influences the risk of developing fatal and non-fatal arterial cardiovascular events in men with a first myocardial infarction (MI).

METHODS

We performed a cohort study among 542 MI patients with a mean age of 56 years (range 32-70 years) at the time of the event. All of the men had a first MI between 1990 and 1996 and were followed until 1 September 2004. DNA was analyzed for polymorphisms of fibrinogen, prothrombin (factor II), factor V, factor VII and plasminogen activator inhibitor type 1, all of which are associated with gain of function of the protein. We collected information from hospital files and general practitioners on the occurrence of major arterial events.

RESULTS

In total, 254 major arterial cardiovascular events occurred during a median follow-up period of 11 years (range 0.2-15 years). The point estimates of the relative rates (RRs) of these events for the variant genotypes were all between 0.7 and 1.1 except for the prothrombin 20210A mutation: RR 1.8 (95% confidence interval 0.8-4.1).

CONCLUSION

These findings suggest that there is no association between coagulation factor polymorphisms, previously associated with plasma levels, and the risk of recurrent cardiovascular events.

Factor VII, blood lipids and fat intake: gene-nutrient interaction and risk of coronary heart disease with the factor VII R353Q polymorphism

BACKGROUND

The relation between dietary fat, blood lipids, plasma factor VII coagulant activity (FVIIc) and risk of coronary heart disease (CHD) according to the R353Q polymorphism in the factor VII gene was assessed.

METHODS

Cross-sectional study of 15,073 individuals participating in the European Prospective Investigation of Cancer (EPIC) Norfolk, 7433 of which had FVIIc available. Nested case-control study of 985 CHD cases and 2009 matched controls.

RESULTS

FVIIc was significantly associated with total fat intake in females, especially in the RR homozygotes (standardized beta=0.24; 95% confidence interval (95% CI) 0.08-0.40; P<0.01), but there were no associations with intakes of saturated, monounsaturated or polyunsaturated fatty acids according to genotype and no associations in males. FVIIc was significantly positively associated with total cholesterol (P<0.01) and with triacylglycerol (P<0.001) in both genders, with an interaction according to genotype for triacylglycerol in males: beta Q allele carriers 0.26 (95% CI 0.18-0.34), beta RR homozygotes 0.16 (95% CI 0.12-0.20) (Z interaction=-2.24; P<0.05). There was no effect of genotype on the odds ratio (OR) for incident CHD: OR 0.89 for Q allele carriers compared with RR homozygotes (95% CI 0.77-1.02) in 985 cases and 2009 matched controls.

CONCLUSION

These results show a strong association between dietary fat intake and FVIIc in women, and between serum triacylglycerol and cholesterol and FVIIc levels in both genders. The R353Q genotype only marginally affected modulation of FVIIc by dietary fat. The association between triacylglycerol and FVIIc was significantly stronger in males carrying the Q allele than in those with the RR genotype.

Evidence for an overlapping role of CLOCK and NPAS2 transcription factors in liver circadian oscillators

The mechanisms underlying the circadian control of gene expression in peripheral tissues and influencing many biological pathways are poorly defined. Factor VII (FVII), the protease triggering blood coagulation, represents a valuable model to address this issue in liver since its plasma levels oscillate in a circadian manner and its promoter contains E-boxes, which are putative DNA-binding sites for CLOCK-BMAL1 and NPAS2-BMAL1 heterodimers and hallmarks of circadian regulation. The peaks of FVII mRNA levels in livers of wild-type mice preceded those in plasma, indicating a transcriptional regulation, and were abolished in Clock(-/-); Npas2(-/-) mice, thus demonstrating a role for CLOCK and NPAS2 circadian transcription factors. The investigation of Npas2(-/-) and Clock(Delta19/Delta19) mice, which express functionally defective heterodimers, revealed robust rhythms of FVII expression in both animal models, suggesting a redundant role for NPAS2 and CLOCK. The molecular bases of these observations were established through reporter gene assays. FVII transactivation activities of the NPAS2-BMAL1 and CLOCK-BMAL1 heterodimers were (i) comparable (a fourfold increase), (ii) dampened by the negative circadian regulators PER2 and CRY1, and (iii) abolished upon E-box mutagenesis. Our data provide the first evidence in peripheral oscillators for an overlapping role of CLOCK and NPAS2 in the regulation of circadianly controlled genes.

Combined effect of hemostatic gene polymorphisms and the risk of myocardial infarction in patients with advanced coronary atherosclerosis

Background

Relative little attention has been devoted until now to the combined effects of gene polymorphisms of the hemostatic pathway as risk factors for Myocardial Infarction (MI), the main thrombotic complication of Coronary Artery Disease (CAD). The aim of this study was to evaluate the combined effect of ten common prothrombotic polymorphisms as a determinant of MI.

Methodology/Principal Findings

We studied a total of 804 subjects, 489 of whom with angiographically proven severe CAD, with or without MI (n = 307; n = 182; respectively). An additive model considering ten common polymorphisms [Prothrombin 20210G>A, PAI-1 4G/5G, Fibrinogen β -455G>A, FV Leiden and “R2”, FVII -402G>A and -323 del/ins, Platelet ADP Receptor P2Y12 -744T>C, Platelet Glycoproteins Ia (873G>A), and IIIa (1565T>C)] was tested. The prevalence of MI increased linearly with an increasing number of unfavorable alleles (χ² for trend = 10.68; P = 0.001). In a multiple logistic regression model, the number of unfavorable alleles remained significantly associated with MI after adjustment for classical risk factors. As compared to subjects with 3-7 alleles, those with few (≤2) alleles had a decreased MI risk (OR 0.34, 95%CIs 0.13–0.93), while those with more (≥8) alleles had an increased MI risk (OR 2.49, 95%CIs 1.03–6.01). The number of procoagulant alleles correlated directly (r = 0.49, P = 0.006) with endogenous thrombin potential.

Conclusions

The combination of prothrombotic polymorphisms may help to predict MI in patients with advanced CAD.

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.

An LRP8 variant is associated with familial and premature coronary artery disease and myocardial infarction

Our previous genomewide linkage scan of 428 nuclear families (GeneQuest) identified a significant genetic susceptibility locus for premature myocardial infarction (MI) on chromosome 1p34-36. We analyzed candidate genes in the locus with a population-based association study involving probands with premature coronary artery disease (CAD) and/or MI from the GeneQuest families (381 cases) and 560 controls without stenosis detectable by coronary angiography. A nonconservative substitution, R952Q, in LRP8 was significantly associated with susceptibility to premature CAD and/or MI by use of both population-based and family-based designs. Three additional white populations were used for follow-up replication studies: another independent cohort of CAD- and/or MI-affected families (GeneQuest II: 441 individuals from 22 pedigrees), an Italian cohort with familial MI (248 cases) and 308 Italian controls, and a separate Cleveland GeneBank cohort with sporadic MI (1,231 cases) and 560 controls. The association was significantly replicated in two independent populations with a family history of CAD and/or MI, the GeneQuest II family-based replication cohort and the Italian cohort, but not in the population with sporadic disease. The R952Q variant of LRP8 increased activation of p38 mitogen-activated protein kinase by oxidized low-density lipoprotein. This extensive study, involving multiple independent populations, provides the first evidence that genetic variants in LRP8 may contribute to the development of premature and familial CAD and MI.

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.

CCAAT/enhancer-binding protein-beta participates in insulin-responsive expression of the factor VII gene

Expression of the human coagulation factor VII (FVII) gene by hepatoma cells was modulated in concert with levels of glucose and insulin in the culture medium. In low glucose medium without insulin, amounts of both FVII mRNA and secreted FVII protein were coordinately increased; in the presence of glucose with insulin, both were decreased. Analysis of the FVII promoter showed that these effects could be reproduced in a reporter-gene system, and a small promoter element immediately upstream of the translation start site of the gene, which mediated these effects, was identified. Mutation of this element largely abrogated the glucose/insulin-responsive change in expression of the reporter gene. Several members of the CCAAT/enhancer-binding protein family were found to be capable of binding the identified sequence element but not the mutated element. The expression of a FVII minigene directed by a segment of the native FVII promoter responded to co-expressed activating and inhibiting forms of CCAAT/enhancer-binding protein beta.

ALOX5AP gene variants and risk of coronary artery disease: an angiography-based study

The aim of this study was to explore the role of variants of the gene encoding arachidonate 5-lipoxygenase-activating protein (ALOX5AP) as possible susceptibility factors for coronary artery disease (CAD) and myocardial infarction (MI) in patients with or without angiographically proven CAD. A total of 1431 patients with or without angiographically documented CAD were examined simultaneously for seven ALOX5AP single-nucleotide polymorphisms, allowing reconstruction of the at-risk haplotypes (HapA and HapB) previously identified in the Icelandic and British populations. Using a haplotype-based approach, HapA was not associated with either CAD or MI. On the other hand, HapB and another haplotype within the same region (that we named HapC) were significantly more represented in CAD versus CAD-free patients, and these associations remained significant after adjustment for traditional cardiovascular risk factors by logistic regression (HapB: odds ratio (OR) 1.67, 95% confidence interval (CI) 1.04-2.67; P=0.032; HapC: OR 2.41, 95% CI 1.09-5.32; P=0.030). No difference in haplotype distributions was observed between CAD subjects with or without a previously documented MI. Our angiography-based study suggests a possible modest role of ALOX5AP in the development of the atheroma rather than in its late thrombotic complications such as MI.

Coagulation factor VII gene haplotypes, obesity-related traits, and cardiovascular risk in young women

BACKGROUND

Associations between common F7 haplotypes, plasma factor VII (FVII) levels, and cardiovascular risk have recently been reported in population studies involving predominantly European men.

METHODS

We assessed associations between F7 haplotypes and cardiovascular risk in two US population-based studies: a case-control study of these alleles related to a decreased risk of arterial thrombotic outcomes such as myocardial infarction (MI) in young-to-middle-aged women (n = 671), and a cohort study of cardiovascular disease risk factors in young women (n = 1040).

RESULTS

The high-expression F7 haplotype B (containing the promoter variant allele -402A) was associated with an increased FVII level among controls, but not with MI risk. Women carrying a> or =1 copy of the low FVII expression level haplotype C (containing the -401T/-323del/-122C and Gln353 alleles) had decreased FVII levels and decreased risk of MI (odds ratio 0.54, 95% CI 0.31-0.93) compared with women homozygous for the most common haplotype A. Haplotype C was also associated with a decreased body mass index (BMI) and an increased high-density lipoprotein (HDL) cholesterol level, but not with MI risk after adjustment for these metabolic risk factors. In a cohort study composed of young US women, individuals homozygous for haplotype C had a lower BMI and lower systolic blood pressure, but the association between the F7 haplotype and HDL cholesterol was not confirmed.

CONCLUSION

Common FVII haplotypes may contribute to the risk of MI in women, but the mechanisms appear complex. The association between F7 haplotypes and MI susceptibility may be mediated in part through an influence on atherogenic risk factors such as BMI.

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.

Carotid atherosclerotic plaque instability in patients with acute myocardial infarction

The instability of atherosclerotic plaque is partly determined by local factors, but systemic factors such as infection, inflammation, autoimmunity or genes might also be important. We aimed to analyze whether patients with acute myocardial infarction (AMI) might have a higher proportion of unstable plaques in the carotid arteries compared with patients who had had no acute coronary events.

METHODS

Sixty-nine consecutive patients with AMI (Group 1) and 95 patients without acute coronary events (Group 2) had carotid artery duplex ultrasounds. Carotid atherosclerosis was quantified by number of plaques in the two carotid arteries, intimal media thickening and degree of maximal stenosis. According to their morphology, plaques were divided into stable (fibrocalcific) and unstable (soft and/or not homogeneous).

RESULTS

The two groups did not differ as regards age (66+/-8 vs. 68+/-19; p=0.3), female sex (13% vs. 21%; p=0.3), mean number of carotid plaques (2.8+/-1 vs. 2.5+/-2; p=0.2), degree of stenosis (59+/-2% vs. 36+/-1%; p=0.2) or intimal media thickening (1.04+/-0.2 vs. 1.06+/-0.2; p=0.8). However, Group 1 pts more frequently had unstable carotid plaques compared with Group 2 (43% vs. 15%; p=0.004), and had a greater number of unstable carotid plaques (0.51+/-0.6 vs. 0.16+/-0.4: p<0.0001) and a higher ratio of unstable to stable plaque (19% vs. 8%; p=0.005). In the overall population, logistic regression analysis showed that after adjustment for degree of maximal stenosis, the presence of coronary artery event (AMI pts) predicted the presence of unstable carotid plaque (OR: 4.3 95% CI: 2.0-9.2; p=0.0002).

CONCLUSION

Patients with unstable coronary artery disease expressed clinically as AMI, frequently had unstable atherosclerotic plaques in other arterial sites such as carotid arteries. This finding supports the hypothesis that plaque instability might reflect a systemic process.

Genetic polymorphisms of hemostasis genes and primary outcome of very low birth weight infants

BACKGROUND

Recent investigations have reported an influence of thrombophilic mutations and antithrombotic risk factors with development of intraventricular hemorrhage. It was our objective for this study to investigate the impact of genetic polymorphisms of hemostasis genes on the primary outcome measures of sepsis, bronchopulmonary dysplasia, intraventricular hemorrhage, and periventricular leukomalacia in a large cohort of very low birth weight infants.

METHODS

There were 586 very low birth weight infants enrolled prospectively in a multicenter trial between September 2003 and July 2005, and an additional 595 very low birth weight infants, who had been recruited in a previous prospective trial, were studied. DNA samples were taken by buccal swab, and genotypes of factor V Leiden mutation, prothrombin G20210A mutation, the factor VII-323 del/ins polymorphism, and the factor XIII-Val34Leu polymorphisms were determined by polymerase chain reaction and restriction enzyme digestion.

RESULTS

In contrast to data published previously, the frequency of intraventricular hemorrhage or periventricular leukomalacia was not significantly influenced by any of the genetic variants tested. Carriers of the factor XIII-Val34Leu polymorphism, however, had a higher sepsis rate and a longer period of hospital care compared with noncarriers. The factor VII-323 del/ins polymorphism was found to be a potential protective factor against bronchopulmonary dysplasia.

CONCLUSIONS

We could not confirm previously reported associations of hemostasis gene variants and development of intraventricular hemorrhage in very low birth weight infants. To better understand gene-disease associations in very low birth weight infants, the prospective development of large-scale cohorts with well-defined phenotypes and corresponding DNA samples is essential.

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.

Coagulation and atherothrombotic disease

Atherothrombotic disease arises secondary to a complex gene-environment interaction. In the initial stages, the condition is clinically silent but with more advanced disease, an occlusive thrombus is formed resulting in the classical clinical manifestations. Both environmental factors and genetic variations in elements of the clotting cascade influence thrombosis risk by inducing quantitative and qualitative changes in the mature protein, which may affect the final structure of the clot and determine its resistance to lysis. Understanding the fine details of gene-environment interactions in relation to thrombus formation will help to shed more light on disease pathogenesis. Consequently, this will allow the development of more efficacious treatment strategies and will also help to identify subjects at risk, thereby enabling the introduction of early preventative measures.

Platelet glycoprotein IIb/IIIa polymorphism and coronary artery disease: implications for clinical practice

Membrane glycoprotein (GP) IIb/IIIa plays a major role in platelet function; indeed it enables stimulated platelets to bind fibrinogen and related adhesive proteins, a process that is considered key in the development of thrombosis. The gene encoding GPIIIa (ITGB3, also known as GP3A) shows a common platelet antigen polymorphism [PL(A1)/PL(A2); expressed by alleles ITGB3*001 and ITGB3*002] that was variably associated with vascular disease. In 1996, the presence of the PL(A2) allele (ITGB3*001) was first reported to increase the risk of coronary heart disease. Shortly after, the interest in this study was increased by the publication of a case report on the death from myocardial infarction of an Olympic athlete who was found to be homozygous for the PL(A2) allele. Overviews of the published studies on the PL(A1)/PL(A2) polymorphism and coronary risk suggest an influence of the PL(A2) allele on the clinical phenotype and the interaction with other environmental factors. In particular, the strongest effect of the ITGB3 PL(A2) allele was expressed on the risk of occlusion after revascularization procedures, mainly after stent implantation, a condition in which platelet activation is more important as compared with other stenotic mechanisms. In the future, the identification of patients who are particularly responsive to GPIIb/IIIa antagonist therapy (e.g. those with the PL(A2) allele) might help to improve the treatment efficacy in this relatively small population. In a mechanism possibly unrelated to its effect on platelet reactivity to aggregating stimuli, the presence of the PL(A2) allele might influence the antiaggregatory effect of platelet inhibitory drugs such as aspirin (acetylsalicylic acid), clopidogrel, and GPIIb/IIIa antagonists. Although interesting, current data does not yet have direct clinical implications for patient risk identification and drug therapy tailoring. Larger studies are necessary to define the role of the PL(A2) allele in more homogeneous groups where platelet GPIIb/IIIa activation might be particularly relevant.

Influence of warfarin therapy on activated factor VII clotting activity

Oral anticoagulant therapy has been widely employed to prevent and treat a variety of thrombotic disorders, although a new generation of antithrombotic drugs, which offer inhibition of clot-bound as well as fluid-phase thrombin, has been developed and tested in several clinical trials. Although most anticoagulant responses to hydroxycoumarin compounds are well established, there are controversial evidences on their influence on activated factor VII (FVIIa). After analyzing the prothrombin time (PT) (International Normalized Ratio reference range, 0.92-1.08), factor VII clotting activity (FVII:C) (reference range, 75-130 U/dl) and activated factor VII clotting activity (FVIIa:C) (reference range, 30-110 U/l) in 46 consecutive patients on stable warfarin therapy for atrial fibrillation, a consistent trend towards decreased values of both FVII:C and FVIIa:C was observed as PT values increased. At moderate-intensity anticoagulation, with international normalized ratios between 2 and 3, the mean activities of FVII:C and FVIIa:C dropped to 28 U/dl (range, 9-61 U/dl) and 5.8 U/l (range, 1-18 U/l), respectively. Results of our investigations indicate that warfarin therapy decreases FVIIa:C, highlighting the potential benefits of oral anticoagulants in thrombotic disorders and other clinical conditions characterized by increased levels of FVIIa. Owing to the good correlation with FVIIa:C, we also hypothesize that the PT and/or FVII:C might be employed for monitoring recombinant FVIIa therapy.

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.

Transgenic mouse overexpressing syntaxin-1A as a diabetes model

Soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE) protein syntaxin-1A (STX-1A) plays a role not only in exocytosis, but also binds and regulates Ca(2+) and K(+) (voltage-gated K(+) and ATP-sensitive K(+) channels) to influence the sequence of events leading to secretion. Islet levels of STX-1A and cognate SNARE proteins are reduced in type 2 diabetic rodents, suggesting their role in dysregulated insulin secretion contributing to the abnormal glucose homeostasis. We investigated the specific role of STX-1A in pancreatic beta-cells by generating transgenic mice, which express a moderately increased level ( approximately 30% higher) of STX-1A in pancreatic islets (hereafter called STX-1A mice). The STX-1A mice displayed fasting hyperglycemia and a more sustained elevation of plasma glucose levels after an intraperitoneal glucose tolerance test, with correspondingly reduced plasma insulin levels. Surprisingly, beta-cells from the STX-1A male mice also exhibited abnormal insulin tolerance. To unequivocally determine the beta-cell secretory defects, we used single-cell analyses of exocytosis by patch clamp membrane capacitance measurements and ion channel recordings. Depolarization-evoked membrane capacitance increases were reduced in the STX-1A mouse islet beta-cells. The STX-1A mouse also exhibited reduced currents through the Ca(2+) channels but little change in the voltage-gated K(+) channel or ATP-sensitive K(+) channel. These results suggest that fluctuation of islet STX-1A levels in diabetes could influence the pathological and differential regulation of beta-cell ion channels and the exocytotic machinery, collectively contributing to the impaired insulin secretion.

Postprandial activation of hemostatic factors: role of dietary fatty acids

Intake of dietary fat is an important determinant of the plasma concentration of triacylglycerol-rich lipoproteins, and the degree of alimentary lipemia is reported to have effects on hemostatic status including platelet function. Although association between the amount of dietary fat intake, lipemic response and certain cardiovascular disease (CVD) risk factors (VIIa and PAI-1) has been reported, the significance of the fatty acid composition of ingested fat for the postprandial lipid concentrations and the hemostatic factors is still unclear. Accumulating evidence suggests a relationship between dietary fatty acids and emerging hemostatic CVD risk factors, although much of this evidence is incomplete or conflicting. In order to improve our knowledge in this area, sufficient sample size in future studies are required to take into account of the genetic variation (gene polymorphisms for VII, PAI-1), sex, physical activity, stage of life factors, and sufficient duration to account for adaptation for definitive conclusions.

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.

A protective contribution of the Q allele of the R353Q polymorphism of the Factor VII gene in individuals with chronic stable angina?

BACKGROUND

Factor VII polymorphisms have been suggested in some studies to show an association with some aspects of coronary disease, and there is a known association between FVII levels and polymorphic variants in the gene. The aim of the study was to assess whether Factor VII polymorphism R353Q is associated with the extent of coronary artery disease in patients with chronic stable angina.

METHODS AND RESULTS

There is evidence that Factor VII polymorphisms are markers of susceptibility to coronary artery disease (CAD), but two studies have suggested that there is no association between the degree of vessel disease and these polymorphisms. One of these studies did not exclude patients with unstable angina or MI. We therefore set up a prospective cohort study to determine Factor VIIa, VIIc and VIIAg levels, genotype for R353Q, lipid status, smoking history and the degree of vessel disease, in patients attending the hospital for routine day case angiography over a 20 month period. From 519 cases, 400 had no previous MI or revascularisation, including 153 with zero vessel disease, and were successfully genotyped: 9 (2%) QQ, 78 (20%) RQ and 313 (78%) RR. Compared with RR subjects, heterozygotes were 2.7 years older (95% CI: 0.3, 5.0; p=0.027), but were not significantly different regarding gender, cholesterol, extent of vessel disease or smoking history. If those with vessel disease were considered, then the heterozygotes were 3.5 years older than the RR homozygotes (95% CI: 0.6-6.4, p=0.016). There was a significant association between all measures of Factor VII and the R353Q polymorphism, with the Q allele associating with lower levels. There was no significant association between the degree of vessel disease and genotype.

CONCLUSIONS

The degree of vessel disease as seen at day case angiography is independent of polymorphism status, but there appears nonetheless to be a moderate protective effect of the Q allele against stable angina, in that angiographic investigation occurs a few years later for RQ heterozygotes than RR homozygotes. The effect may be mediated by reduced levels of Factor VII.

Daily and Circadian Rhythms of Tissue Factor Pathway Inhibitor and Factor VII Activity

Objective— Diurnal variations in levels of factor VII (FVII), FVIII, proteins C and S, antithrombin, plasminogen activator inhibitor-1, prothrombin fragment F 1+2 , and D-dimers in healthy humans point to the existence of circadian rhythms of coagulation factors. We sought for temporal fluctuations of tissue factor pathway inhibitor (TFPI) activity in human and mouse plasma.

Methods and Results— TFPI activity showed significant daily variations with highest levels in the morning in healthy men (+11%) and in mice at the light-to-dark transition (+63%), the beginning of the physically active period. Variations in FVII activity paralleled those in TFPI. In mice, the feeding schedule had a strong impact on these rhythms. Although restricted feeding and fasting shifted the peak of TFPI, the FVII peak disappeared. Investigation of temporal fluctuations in constant darkness indicated the existence of daily rhythms for TFPI and of true circadian rhythms for FVII.

Conclusions— For the first time, we report, both in humans and mice, temporal variations in TFPI activity. The coherent variations in FVII and TFPI activity could interplay to maintain the coagulation equilibrium. The chronobiological patterns should be considered to analyze activity levels of these factors. Moreover, the mouse model could be exploited to investigate modifiers of coagulation rhythms potentially associated to morning peaks of cardiovascular events.

A part le fibrinogène, les facteurs/marqueurs d’hémostase ont-ils aussi une place pour évaluer le risque d’accident cardiovasculaire ischémique ?

Most cardiovascular events result from a thrombotic complication of atherosclerotic lesions. In arterial vessels such as the coronary bed, an interrelationship of haemostatic, coagulation and fibrinolytic factors is implicated. While it can be demonstrated that fibrinogen is a risk factor/marker, the role of other factors is not well established. Under arterial flow conditions, platelets are predominantly involved in the thrombotic reaction. Yet, apart from a large increase in the platelet count, the involvement of platelet parameters in cardiovascular risk is not clearly evident. The lack of definitive platelet markers is at least partly due to the difficulty of studying platelet function ex vivo. Several polymorphisms of platelet glycoproteins carrying a moderate increase in risk have been reported, but only in younger patients. One potentially important factor for coagulation is the fibrin structure, which is dependent on fibrinogen, the rate of thrombin generation, the activity of factor XIII and the interrelationship of the cells concerned, all of which act on its sensitivity to thrombosis. Coagulation factors largely affect the rate of thrombin generation. The activity of the fibrinolytic system (and principally any deficiency) has a role in the cardiovascular risk. General markers of cardiovascular risk such as D-dimers are potentially useful, but they increase with thrombin generation and are decreased by a deficiency in fibrinolysis. Furthermore, possibly because they are not indicative of the fibrin structure, they are poorly correlated with clinical events. The poor significance of the available haemostatic, coagulation and/or fibrinolytic parameters is probably due to their lack of representativeness, since haemostatic, coagulation and fibrinolytic systems are all involved in the thrombotic response (and some in atherogenesis itself). Atherogenesis is a multifactorial process and numerous moderate risk factors act in association. Better predictability of the haemostatic tests would probably result from both the design of more representative tests and the evaluation of multiple parameters, and would lead to the definition of a risk score. Technological advances will make this possible.

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.

Prevalence in a Tunisian Arabic population of factor VII DNA variants and relation to factor VII plasma levels

BACKGROUND

A raised plasma factor VII (FVII) level is a risk factor for coronary heart disease. DNA variants have been described to be associated with alteration in FVII levels. The prevalence of FVII polymorphisms is unknown in the Tunisian Arab population.

METHODS

In a group of 240 healthy Tunisians, we examined the relationship between levels of FVII coagulant activity (FVIIc) and two polymorphisms in the FVII gene. One polymorphism alters arginine at position 353 to glutamine (R/Q) and the other is a 10 base pair insertion (0/10 bp).

RESULTS

The FVII distribution was in accordance with the Hardy-Weinberg equilibrium. The allele frequencies of Q and 10 bp were 0.212 and 0.235, respectively. There were significant differences in these allelic frequencies between Tunisian and other populations (p<0.001). We observed lower FVIIc levels among subjects with the Q allele compared to RR subjects (RR: 98.17%, RQ/QQ: 57.41%, p<0.0001). For the 0/10 polymorphism, no statistically difference was observed.

CONCLUSION

The prevalence of the Q allele which was found to be associated with lower plasma FVIIc levels is high in Tunisian population. Further analyses should yield information on the protective role of carrying the Q allele for coronary heart disease.

Association Between Factor VII Polymorphisms and Blood Pressure

The purpose this study was to determine whether Arg353Gln and −323Del/Ins polymorphisms of factor VII (FVII) are related to blood pressure levels and hypertension. Subjects were drawn from the Stanislas Cohort, a longitudinal, familial French cohort examined twice since 1994. The “blood pressure study” included 1342 subjects free of medication use that could affect blood pressure. The “hypertension study” included 645 normotensive and 77 hypertensive adult subjects. Association with hypertension was also studied in 547 hypertensives enrolled in a clinical trial and in 624 normotensives drawn from the Stanislas Cohort. In the “blood pressure study,” parents with the 353Gln or −323Ins allele had lower blood pressures than did noncarriers at each examination, independent of covariates (0.01≤ P ≤0.05, except for diastolic blood pressure [DBP] at baseline, where P =0.103). Similarly significant relations were observed in their offspring ( P ≤0.05, except for systolic blood pressure [SBP] at 5 years, where P =0.186). In a representative subgroup of 267 individuals, the −323Del/Ins polymorphism was significantly associated with plasma FVII levels in both parents and offspring ( P <0.001). FVII levels in plasma were significantly correlated with SBP and DBP in parents but not in offspring. After inclusion of both FVII levels and the −223Del/Ins in the same model in parents, only FVII levels remained significantly associated with SBP and DBP. The “hypertension study” revealed that the 353Gln and −323Ins alleles were related to decreased risk (odds ratio [OR]=0.554, 95% confidence interval [CI], 0.362 to 0.848, and OR=0.475, 95% CI, 0.299 to 0.755, respectively). These results suggest that the FVII gene may be a susceptibility locus for hypertension.