A follow-up study of a genome-wide association scan identifies a susceptibility locus for venous thrombosis on chromosome 6p24.1.

To identify genetic susceptibility factors conferring increased risk of venous thrombosis (VT), we conducted a multistage study, following results of a previously published GWAS that failed to detect loci for developing VT. Using a collection of 5862 cases with VT and 7112 healthy controls, we identified the HIVEP1 locus on chromosome 6p24.1 as a susceptibility locus for VT. Indeed, the HIVEP1 rs169713C allele was associated with an increased risk for VT, with an odds ratio of 1.20 (95% confidence interval 1.13-1.27, p = 2.86 x 10(-9)). HIVEP1 codes for a protein that participates in the transcriptional regulation of inflammatory target genes by binding specific DNA sequences in their promoter and enhancer regions. The current results provide the identification of a locus involved in VT susceptibility that lies outside the traditional coagulation/fibrinolysis pathway.

Sensitive troponin I assay in early diagnosis of acute myocardial infarction.

BACKGROUND: Cardiac troponin testing is central to the diagnosis of acute myocardial infarction. We evaluated a sensitive troponin I assay for the early diagnosis and risk stratification of myocardial infarction. METHODS: In a multicenter study, we determined levels of troponin I as assessed by a sensitive assay, troponin T, and traditional myocardial necrosis markers in 1818 consecutive patients with suspected acute myocardial infarction, on admission and 3 hours and 6 hours after admission. RESULTS: For samples obtained on admission, the diagnostic accuracy was highest with the sensitive troponin I assay (area under the receiver-operating-characteristic curve [AUC], 0.96), as compared with the troponin T assay (AUC, 0.85) and traditional myocardial necrosis markers. With the use of the sensitive troponin I assay (cutoff value, 0.04 ng per milliliter) on admission, the clinical sensitivity was 90.7%, and the specificity was 90.2%. The diagnostic accuracy was virtually identical in baseline and serial samples, regardless of the time of chest-pain onset. In patients presenting within 3 hours after chest-pain onset, a single sensitive troponin I assay had a negative predictive value of 84.1% and a positive predictive value of 86.7%; these findings predicted a 30% rise in the troponin I level within 6 hours. A troponin I level of more than 0.04 ng per milliliter was independently associated with an increased risk of an adverse outcome at 30 days (hazard ratio, 1.96; 95% confidence interval, 1.27 to 3.05; P=0.003). CONCLUSIONS: The use of a sensitive assay for troponin I improves early diagnosis of acute myocardial infarction and risk stratification, regardless of the time of chest-pain onset.

Separating the mechanism-based and off-target actions of cholesteryl ester transfer protein inhibitors with CETP gene polymorphisms.

BACKGROUND: Cholesteryl ester transfer protein (CETP) inhibitors raise high-density lipoprotein (HDL) cholesterol, but torcetrapib, the first-in-class inhibitor tested in a large outcome trial, caused an unexpected blood pressure elevation and increased cardiovascular events. Whether the hypertensive effect resulted from CETP inhibition or an off-target action of torcetrapib has been debated. We hypothesized that common single-nucleotide polymorphisms in the CETP gene could help distinguish mechanism-based from off-target actions of CETP inhibitors to inform on the validity of CETP as a therapeutic target. METHODS AND RESULTS: We compared the effect of CETP single-nucleotide polymorphisms and torcetrapib treatment on lipid fractions, blood pressure, and electrolytes in up to 67 687 individuals from genetic studies and 17 911 from randomized trials. CETP single-nucleotide polymorphisms and torcetrapib treatment reduced CETP activity and had a directionally concordant effect on 8 lipid and lipoprotein traits (total, low-density lipoprotein, and HDL cholesterol; HDL2; HDL3; apolipoproteins A-I and B; and triglycerides), with the genetic effect on HDL cholesterol (0.13 mmol/L, 95% confidence interval [CI] 0.11 to 0.14 mmol/L) being consistent with that expected of a 10-mg dose of torcetrapib (0.13 mmol/L, 95% CI 0.10 to 0.15). In trials, 60 mg of torcetrapib elevated systolic and diastolic blood pressure by 4.47 mm Hg (95% CI 4.10 to 4.84 mm Hg) and 2.08 mm Hg (95% CI 1.84 to 2.31 mm Hg), respectively. However, the effect of CETP single-nucleotide polymorphisms on systolic blood pressure (0.16 mm Hg, 95% CI -0.28 to 0.60 mm Hg) and diastolic blood pressure (-0.04 mm Hg, 95% CI -0.36 to 0.28 mm Hg) was null and significantly different from that expected of 10 mg of torcetrapib. CONCLUSIONS: Discordance in the effects of CETP single-nucleotide polymorphisms and torcetrapib treatment on blood pressure despite the concordant effects on lipids indicates the hypertensive action of torcetrapib is unlikely to be due to CETP inhibition or shared by chemically dissimilar CETP inhibitors. Genetic studies could find a place in drug-development programs as a new source of randomized evidence for drug-target validation in humans.

Contribution of SELP and PSGL-1 genotypes and haplotypes to the presence of coronary heart disease in Tunisians.

P-selectin (SELP) and its counter-receptor, P-selectin glycoprotein ligand-1 (PSGL-1), play key role in the transient attachment of leukocytes to endothelial cells predisposing to coronary heart disease (CHD). In the current report, 293 angiographically proven CHD patients and 327 age, gender, and race-matched controls were included. Our aim was to evaluate the contribution to CHD of the following SNPs: C-2123G, G-1969A and T715P in SELP, Met62Ile and the VNTR variants in PSGL-1 gene in a North African population from Tunisia. While there were no significant differences in the distribution of SELP or PSGL-1 alleles or genotypes between patients and controls, a trend for a significant association of the C-2123G genotypes distribution with incident CHD was observed (P=0.06). Assuming an additive model of transmission, the risk was 74% higher among subjects carrying the GG genotypes in comparison to those carrying the CC genotype (OR=1.74 [1.01-2.98], P=0.04) and 80% higher in the recessive model (OR=1.80 [1.08-3.01], P=0.02). Haplotype analysis did not identify any specific SELP or PSGL-1 haplotypes to be associated with CHD. The present study demonstrated no evidence of association between individual SELP or PSGL-1 SNPs or haplotypes with incident CHD. However, this study replicates absence of association of the mostly studied SNP, T715P, previously reported in individuals with African origin.

Molecular genetic analysis of a human insulin-like growth factor 1 promoter P1 variation.

Insulin-like growth factor 1 (IGF1) exerts important endocrine and paracrine functions in the cardiovascular system. We identified the common variant -1411C>T in the IGF1 upstream promoter P1, located within several overlapping transcription factor binding sites. Using transient transfection assays, we identified this site as a functional enhancer. The T allele-carrying enhancer, compared with the C allelic portion, exerts significantly reduced or even abrogated activity, respectively, in SaOs-2 and HepG2 (all P<0.0001) as well as in differentiated THP-1 macrophages. Electrophoretic mobility shift assay and subsequent supershift experiments in HepG2 identified c-Jun as the binding partner exclusively to the T allele, whereas CCAAT/enhancer-binding protein delta and interferon consensus site-binding protein/interferon-regulating factor 8 interacted only with the C allelic promoter portion. Furthermore, genotyping in a case-control study for essential hypertension (n=745 hypertensive patients; n=769 normotensive control subjects) for this variant revealed an odds ratio for hypertension of 0.73 (95% confidence interval 0.58-0.91, P=0.006) associated with the T allele, and normotensive subjects carrying the protective T allele displayed a significant decrease in diastolic (P=0.036) and systolic (P=0.024) blood pressure levels. We here report detection of a functional enhancer module in the upstream IGF1 promoter region, which might play a key role in local IGF1 bioavailability. Whether -1411C>T is also associated with other IGF1-related disease phenotypes should be evaluated further in population studies.

Association of three polymorphisms selected from a genome-wide association study with coronary heart disease in the Tunisian population.

Despite extensive exploration of many genes, strong evidence of a molecular genetic association with coronary heart disease (CHD) or myocardial infarction (MI) remains to be obtained. Recently, significant interest has emerged in mapping genetic susceptibility for complex traits through whole-genome studies association generating promoting data that will determine the genetic contribution to common human diseases such as coronary heart disease. The aim of the present case-control study including 324 healthy controls and 296 patients with coronary heart disease from Tunisia, was to assess relation between three polymorphisms previously reported to be strongly associated with coronary heart disease in the Welcome Trust Case Control Consortium (WTCCC) and the German myocardial infarction family studies: locus 9p21.3 (rs 1333049), locus 6q25.1 (rs6922269) and 2q36.3 (rs2943634). By single locus analysis, no differences in genotype distribution and allelic frequency were found between the two groups of study. The risk allele (C) for rs2943634 was less frequent among Tunisian population than in controls from the WTCCC and German studies (57% vs 65%). The three SNPs previously reported to be associated with CHD were not replicated in our small sample.

Cystatin C and cardiovascular mortality in patients with coronary artery disease and normal or mildly reduced kidney function: results from the AtheroGene study.

AIMS: Chronic kidney disease is associated with increased risk of cardiovascular disease. Cystatin C is a promising marker to reliably mirror renal function. The role of cystatin C in patients with coronary artery disease (CAD) and normal or mildly reduced kidney function is the subject of current investigation. METHODS AND RESULTS: In 2162 patients, over the whole spectrum of CAD, baseline cystatin C concentrations were measured. Patients with an estimated glomerular filtration rate of < or =60 mL/min per 1.73 m(2) (n = 295) were excluded. In patients with complete follow-up information (n = 1827), 66 cardiovascular deaths were registered during a median follow-up of 3.65 years. Logarithmically transformed, standardized cystatin C was associated with cardiovascular death [hazard ratio: 1.94, 95% confidence interval (CI): 1.59-2.37, P < 0.001]. A potential threshold effect was observed; patients in the upper quartile had a 3.87-fold (95% CI: 2.33-6.42; P < 0.001) risk of mortality compared with the pooled lower quartiles. This risk association remained robust after adjustment for potential confounders including classical risk factors and N-terminal pro B-type natriuretic peptide. Serum creatinine was not associated with the outcome in this group of patients with normal renal function. CONCLUSION: Results of this prospective study show that cystatin C is a potent predictor of cardiovascular mortality beyond classical risk factors in patients with CAD and normal or mildly reduced kidney function.

Lack of association between polymorphisms of the IL18R1 and IL18RAP genes and cardiovascular risk: the MORGAM Project.

BACKGROUND: Interleukin-18 is a pro-inflammatory cytokine suspected to be associated with atherosclerosis and its complications. We had previously shown that one single nucleotide polymorphism (SNP) of the IL18 gene was associated with cardiovascular disease (CVD) through an interaction with smoking. As a further step for elucidating the contribution of the IL-18 pathway to the etiology of CVD, we here investigated the association between the genetic variability of two IL-18 receptor genes, IL18R1 and IL18RAP, with the risk of developing CVD. METHODS: Eleven tagging SNPs, 5 in IL18R1 and 6 in IL18RAP, characterizing the haplotypic variability of the corresponding genes; were genotyped in 5 European prospective CVD cohorts including 1416 cases and 1772 non-cases, as part of the MORGAM project. Both single-locus and haplotypes analyses were carried out to investigate the association of these SNPs with CVD. RESULTS: We did not find any significant differences in allele, genotype and haplotype frequencies between cases and non-cases for either of the two genes. Moreover, the search for interactions between SNPs located in different genes, including 5 IL18 SNPs previously studied in the MORGAM project, and between SNPs and environmental factors remained unfruitful. CONCLUSION: Our analysis suggests that the variability of IL18R1 and IL18RAP genes are unlikely to contribute to modulate the risk of CVD.

ANGPTL4 E40K and T266M: effects on plasma triglyceride and HDL levels, postprandial responses, and CHD risk.

BACKGROUND: Angiopoietin-like 4 is a dual-function protein: an inhibitor of LPL, influencing plasma triglycerides (TGs), with angiogenic properties. We examined the association of common ANGPTL4 variants with CHD traits and risk in 5 studies (13,527 individuals). METHODS AND RESULTS: The effects on plasma lipids of 6 tagging SNPs and the recently identified E40K were examined in a study of 2772 men. Only T266M (rs1044250, MAF=30%) and E40K (MAF=2%) were significantly associated with TG-lowering (-10.4%, P<0.004 and -20.4%, P<0.0001), respectively. T266M no longer showed significant associations when K40 carriers (K40+) were excluded (P=0.2). Combining data from 5 studies confirmed the TG-lowering effect of K40+ (weighted mean difference: -0.12 [95% CI -0.18, -0.05] mmol/L TG P=0.0001). Surprisingly, in the 3 prospective studies, the combined OR for CHD was 1.48 (1.11 to 1.96, P=0.007), independent of TG. In individuals with a paternal history of MI (n=332) T266M, but not E40K, showed effects on postprandial AUC TG and glucose (P=0.009 and P=0.017, respectively) compared to controls (n=370). CONCLUSIONS: Although associated with an atheroprotective lipid profile, E40K was associated with increased CHD risk, suggesting Angptl4 influences parameters beyond lipid levels. T266M showed effects only under conditions of postprandial stress. The functionality of these potential "loss-of-function" variants needs validation.

The association of telomere length with paternal history of premature myocardial infarction in the European Atherosclerosis Research Study II.

Inter-individual variability in telomere length is highly heritable and has been correlated with risk of coronary heart disease (CHD). Our aim was to determine the association of mean leukocyte telomere length with paternal history of premature myocardial infarction (MI). Mean leukocyte telomere length was measured with real-time polymerase chain reactions in 369 male students (18-28 years) with a paternal history of MI before the age of 55, recruited from 14 European universities, serving as cases and 396 age-matched controls with no paternal history of CHD. Overall, cases had borderline significantly shorter mean length (approximately 550 bp), adjusted for age and geographical region, than controls (p = 0.05). A significant difference in telomere length across the geographical regions of Europe was observed (p < 0.0001), with shorter mean length in the Baltic and South and the longest in the Middle. The case-control difference ( approximately 2.24 kb) in mean length was highly significant only in the Baltic region (p < 0.0001). There is suggestive evidence that, in young men, the biological expression of a paternal history of premature MI is at least in part mediated through inherited short telomeres. The association with paternal history of MI is strongly seen only in the Baltic compared to the rest of Europe, but this is not explained by shorter telomere length in this region.

P-selectin gene polymorphisms and risk of coronary heart disease among Tunisians.

P-selectin plays a key role in inflammation and atherosclerosis, and polymorphic variants of P-selectin were implicated in the pathogenesis of atherosclerotic and inflammatory changes, including coronary heart disease (CHD) in many ethnic groups. We investigated the contribution of P-selectin promoter (-2123C/G, -1969G/A) and exon (Ser290Asn, Asn562Asp, Thr715Pro) polymorphisms to CHD genetic susceptibility among 298 Tunisian CHD patients and 339 controls. Minor allele and genotype frequencies of the five P-selectin SNPs were comparable between patients and controls, except for -2123G/G genotype which was more frequent in cases. The 715Pro allele was present at lower frequency in Tunisians than in Europeans, and was not protective of CHD. Linkage disequilibrium was seen between -1969G/A, and both Ser290Asn and Asn562Asp. Five-loci haplotype analysis did not identify any CHD-protective or CHD-susceptible haplotypes. To our knowledge, this was the first case-control study to be performed on an Arab/North-African population, and demonstrates that none of the five P-selectin polymorphisms investigated influence CHD susceptibility in Tunisian Arabs.

Haplotypic analysis of tag SNPs of the interleukin-18 gene in relation to cardiovascular disease events: the MORGAM Project.

Interleukin-18 (IL-18) is a key inflammatory molecule suspected of being involved in the etiology of cardiovascular diseases (CVD). Five single nucleotide polymorphisms (SNPs) capturing the common genetic variation of the IL-18 gene (tag SNPs) were genotyped in five European prospective CVD cohorts including 1933 cases and 1938 non-cases as part of the MORGAM Project. Not a single SNP was found associated with CVD. However, a significant (P=0.002) gene-smoking interaction was observed. In smokers, the -105T allele was more frequent in cases than in non-cases (0.29 vs 0.25) and associated with an increased risk of disease (odds ratio (OR)=1.25 (1.07-1.45), P=0.005), whereas the inverse relationship tended to be observed in non-smokers (OR=0.90 (0.78-1.02), P=0.131). The gene-smoking interaction was broadly homogenous across the cohorts and was also observed through haplotype analyses. In conclusion, using the concerted effort of several European prospective CVD cohorts, we are able to show that one IL-18 tag SNP interacts with smoking to modulate the risk of developing CVD.

Haplotypes of the caspase-1 gene, plasma caspase-1 levels, and cardiovascular risk.

Caspase-1 processes the interleukin (IL)-1beta and IL-18 inactive precursors to the biologically active cytokines that are known to have proatherogenic effects. The present study investigated the genetic variability of the CASP1 gene and plasma levels of caspase-1 in relation to cardiovascular risk. In Europeans, 3 tag SNPs captured 4 common haplotypes of the CASP1 gene. Among these, the A(in6) allele of the G+7/in6A polymorphism was less frequent in 246 cases with myocardial infarction and a parental history of disease than in 253 controls free of familial history of disease (0.13+/-0.02 versus 0.20+/-0.02; P=0.005). However, in a larger case/control study (n=1774), these effects are borderline restricted to the UK population. In a prospective cohort of 1168 patients with coronary artery disease followed up during a median period of 6.0 years, the A(in6) allele exhibited a borderline association with future cardiovascular death (hazard ratio [HR]: 0.64, 0.41 to 1.01; P=0.053) and was associated with lower serum IL-18 levels (P=0.014). Baseline caspase-1 levels in the top quartile of the distribution were predictive of cardiovascular deaths (HR=3.62, 1.81 to 7.27; P=0.0003 compared with the bottom quartile). Finally, in vitro assays of allelic imbalance showed that the CASP1 haplotype carrying the A(in6) allele was associated with a lower mRNA expression. These results indicate that caspase-1 levels are predictive of future cardiovascular death in patients with coronary artery disease. The role of CASP1 genetic variations in the susceptibility to myocardial infarction requires further investigation.

Lack of association between complement factor H polymorphisms and coronary artery disease or myocardial infarction.

Complement factor H (CFH) plays a critical role in the protection of host cells and tissues from damage by complement activation and has been suggested to protect against the progression of atherosclerosis. A polymorphism in the CFH gene, Y402H, known to be strongly associated with age-related macular degeneration, has been analyzed in relation to coronary artery disease (CAD) in several studies with conflicting results. We investigated the association of polymorphisms of the CFH gene in two large-scale studies on CAD and myocardial infarction (MI). The AtheroGene Study included a cohort of cases with CAD (n = 1,303) prospectively followed for a median period of 6.2 years, among whom198 experienced a cardiovascular event, and a group of 483 control subjects. The AtheroGene Study population was genotyped for the Y402H, I62V, and E936D polymorphisms. There was no significant difference in genotypic or allelic frequencies between CAD cases and controls. Among cases, no significant association was found with prospective cardiovascular outcome. Many inflammatory proteins, including the C-reactive protein, were measured, and none of the polymorphisms showed an association with these markers. The Etude Cas-Témoin de l'Infarctus du Myocarde (ECTIM) Study compared 1,034 patients with MI and 1,039 controls from France and United Kingdom. The ECTIM Study population was genotyped for the Y402H polymorphism. Genotype and allele frequencies were similar in cases and controls. These results do not support an involvement of common nonsynonymous polymorphisms of the CFH gene in predisposition to CAD and its complications.

Polymorphisms in 33 inflammatory genes and risk of myocardial infarction--a system genetics approach.

The hypothesis of a causal link between inflammation and atherosclerosis would be strengthened if variants of inflammatory genes were associated with disease. Polymorphisms of 33 genes encoding inflammatory molecules were tested for association with myocardial infarction (MI). Patients with MI and a parental history of MI (n = 312) and controls from the UK (n = 317) were genotyped for 162 polymorphisms. Thirteen polymorphisms were associated with MI (P values ranging from 0.003 to 0.041). For three genes, ITGB1, SELP, and TNFRSF1B haplotype frequencies differed between patients and controls (P values < 0.01). We further assessed the simultaneous contribution of all polymorphisms and relevant covariates to MI using a two-step strategy of data mining relying on Random Forest and DICE algorithms. In a replication study involving two independent samples from the UK (n = 649) and France (n = 706), one interaction between the ITGA4/R898Q polymorphism and current smoking status was replicated. This study illustrates a strategy for assessing the joint effect of a large number of polymorphisms on a phenotype that may provide information that single locus or single gene analysis may fail to uncover. Overall, there was weak evidence for an implication of inflammatory polymorphisms on susceptibility to MI.

SAH gene variants are associated with obesity-related hypertension in Caucasians: the PEGASE Study.

OBJECTIVE: The SAH gene locus has recently been proposed to be involved in obesity-related hypertension in Japanese individuals. METHODS: To replicate independently the initial findings in another ethnic group, we scanned the entire SAH gene in 190 Caucasian chromosomes. A total of 651 patients with essential hypertension and 776 controls (PEGASE Study) were genotyped for all identified variants using allele-specific oligonucleotides, and single nucleotide polymorphism as well as haplotype analyses were carried out. We also performed transient transfection experiments, northern and western blots, immunoprecipitation, and acyl-coenzyme A synthetase activity assays. RESULTS: We identified five polymorphisms in the promoter region (C-1808T, G-1606A, -962ins/del, G-451A, T-67C), two in introns 5 and 7 (T+9/In5C, A+20/In7T), and one missense variant (K359N). Carriage of the -1606A allele was significantly associated with hypertension [odds ratio (OR) 1.28, P = 0.049] as was 359N (OR 1.35, P = 0.048) compared with non-carriers. Conversely, for -962del, the OR for hypertension was 0.80 (P = 0.042). The SAH alleles -1606A and 359N, but not -962ins/del, displayed a raising effect on body mass index (BMI; P = 0.004 and P = 0.030, respectively) in hypertensive as well as in control individuals. After adjustment for BMI in hypertensive individuals, only the OR associated with -962ins/del remained significant (OR 0.77, P = 0.028). Functional analyses in BHK did not reveal differences for SAH 359N or 359K-containing constructs, formally excluding K359N as the functional variant. CONCLUSION: We confirm recent evidence that the SAH locus is associated with obesity-related hypertension, in which pathophysiological context SAH variants affecting blood pressure remain, however, to be shown.

Interaction between insulin (VNTR) and hepatic lipase (LIPC-514C>T) variants on the response to an oral glucose tolerance test in the EARSII group of young healthy men.

Insulin resistance is polygenic in origin, and can be observed at an early age. We have shown that variations in APOC3-482T>C and hepatic lipase (LIPC)-514C>T), individually (APOC3 alone) and interactively, modulate insulin and glucose levels after an OGTT in young healthy men participating in the European Atherosclerosis Research Study II (EARSII). Variation in the insulin gene (INS) variable number tandem repeat (VNTR) has been found to predispose to type 1 and type 2 diabetes. We have evaluated the HphI site 23 bp upstream of the INS gene (a surrogate marker for the VNTR) in EARSII (n=822), to determine if variation in INS contributes to insulin resistance. Carriers of the INS VNTR class III (HphI-) allele (frequency=0.29 (95%CI 0.27, 0.31)) had significantly higher 60-min insulin concentrations after the OGTT (P=0.014) and a marginally higher AUC insulin (P=0.07), compared to class I (HphI+) homozygotes. However, this effect on AUC insulin was modified by the level of physical activity, displaying significant gene:environment interaction (P=0.03). We tested for gene:gene interaction between the INS VNTR and both the LIPC-514C>T and APOC3-482T>C. While there was a significant interaction between INS VNTR and LIPC-514C>T on AUC glucose (P=0.013) and on AUC insulin (P=0.015), there was no interaction with APOC3-482T>C. Thus, despite a modest effect of the INS VNTR alone, the influence of this variant on insulin sensitivity was modified by gene:environment and gene:gene interactions, illustrating the biological complexity of insulin resistance.

Genetic analysis of the interleukin-18 system highlights the role of the interleukin-18 gene in cardiovascular disease.

BACKGROUND: Interleukin (IL)-18 plays a key role in atherosclerosis and its complications. The present study investigated the genetic variability of 4 genes of the IL-18 system-IL18, IL18R1, IL18RAP, and IL18BP-in relation to circulating IL-18 levels and cardiovascular mortality. METHODS AND RESULTS: Twenty-two polymorphisms were genotyped in 1288 patients with coronary artery disease prospectively followed up during a median period of 5.9 years. The end point was death from cardiovascular causes (n=142). Baseline IL-18 levels were predictive of cardiovascular deaths occurring during < or =4 years of follow-up (HR=2.96, 95% CI 1.54 to 5.70, P=0.001 for the top compared with the bottom quartile) but not of later deaths. Haplotypes of the IL18 gene were associated with IL-18 levels (P=0.002) and cardiovascular mortality (P=0.006) after adjustment for cardiovascular risk factors. The same haplotype was associated with both a 9% lowering effect on IL-18 levels and a protective effect on risk (HR=0.57, 95% CI 0.36 to 0.92). IL18 haplotypes explained only 2% of IL-18 variability. Adjustment for baseline IL-18 levels abolished the association of haplotypes with cardiovascular risk. The haplotype associated with phenotypes was the only one carrying the minor allele of the IL18/A+183G polymorphism located in the 3'untranslated region and potentially affecting mRNA stability. The other genes of the system were not related to IL-18 levels or cardiovascular outcome. CONCLUSIONS: Variations of the IL18 gene consistently influence circulating levels of IL-18 and clinical outcome in patients with coronary artery disease, which supports the hypothesis of a causal role of IL-18 in atherosclerosis and its complications.

Apolipoprotein AIV gene variant S347 is associated with increased risk of coronary heart disease and lower plasma apolipoprotein AIV levels.

The impact of common variants in the apolipoprotein gene cluster (APOC3-A4-A5) on prospective coronary heart disease (CHD) risk was examined in healthy UK men. Of the 2808 men followed over 9 years, 187 had a clinically defined CHD event. Examination of 9 single nucleotide polymorphisms (SNPs) in this group revealed that homozygotes for APOA4 S347 had significantly increased risk of CHD [hazard ratio (HR) of 2.07 (95%CI 1.04 to 4.12)], whereas men homozygous for APOC3 1100T were protected [HR 0.28 (95%CI 0.09 to 0.87)]. In stepwise multiple regression analysis, after entering all the variants and adjusting for established risk factors APOA4 T347S alone remained in the model. Using all nine SNPs, the highest risk-estimate haplotypes carried APOA4 S347 and rare alleles of the two flanking intergenic markers. The protective effect of APOC3 1100T could be explained by negative linkage disequilibrium with these alleles. To determine the association of APOA4 T347S with apoAIV levels, the relationship was examined in 1600 healthy young European men and women. S347 homozygotes had significantly lower apoAIV plasma levels (13.64+/-0.59 mg/dL) compared with carriers of the T347 allele (14.90+/-0.12 mg/dL) (P=0.035). These results demonstrate that genetic variation in and around APOA4, independent of the effects of triglyceride, is associated with risk of CHD and apoAIV levels, supporting an antiatherogenic role for apoAIV.

Contribution of APOA5 gene variants to plasma triglyceride determination and to the response to both fat and glucose tolerance challenges.

The aim of this study was to investigate the influence of APOA5 variants on fasting lipids and to the response to both an oral fat tolerance test (OFTT) and an oral glucose tolerance test (OGTT). The association of two APOA5 SNPs [S19W (SNP5), -1131T>C (SNP3)] and an APOA4/A5 intergenic SNP [-12238T>C (SNP4)] were examined in healthy young men (n=774) who had undergone both an OFTT and an OGTT. Both -1131T>C and S19W rare alleles were associated with triglyceride (TG)-raising effects (11%, P=0.008; 21% (in cases), P<0.026, respectively) and showed additive effects on TG. None of the variants influenced the responsiveness to the OFTT after correcting for baseline TG. Homozygosity for the -12238T>C rare allele was associated with higher waist to hip ratio (P<0.0006), systolic blood pressure (P=0.012) and AUC and peak of insulin after OGTT (P=0.003 and P=0.027, respectively), traits that define the metabolic syndrome. Our results strongly support the role of APOA5 in determining plasma TG levels in an age-independent manner and highlight the importance of the APOC3/A4/A5 gene cluster in both TG and metabolic homeostasis.