Apolipoprotein E4, lipoprotein lipase C447 and angiotensin-I converting enzyme deletion alleles were not associated with increased wall thickness of carotid and femoral arteries in healthy subjects from the Stanislas cohort

Apolipoprotein E ε2 allele is associated with lower risk of carotid artery obstruction in a population-based autopsy study

INTRODUCTION

Apolipoprotein E (APOE) ε4 allele has been associated with higher carotid atherosclerosis risk, while the APOE-ε2 seems to decrease this risk. Data from autopsy studies, where carotid arteries can be evaluated in their full extension, is scarce. Therefore, we investigated the association between APOE alleles and direct morphometric measurements of carotid atherosclerosis in an autopsy study with an admixed sample.

METHODS

We measured the intima-media thickness (IMT) and stenosis of the common (CCA) and internal carotid (ICA) arteries. The APOE polymorphisms were determined by real-time polymerase chain reaction. Participants were classified into three groups according to the APOE alleles (ε2, ε3, and ε4). We evaluated the association between APOE groups and carotid atherosclerosis using adjusted regression models and included interaction terms of APOE alleles with age, sex, and race.

RESULTS

We evaluated 1,850 carotid artery samples from 185 participants (mean age=75±12 years old, 55% female, and 71% White). The APOE-ε2 group (n=17) had a lower carotid obstruction and a lower number of severe stenoses (≥ 70%). Having at least one ε4 allele (n=51) was not associated with carotid atherosclerosis. APOE alleles were also not associated with carotid IMT. Age, sex, and race did not modify these relationships.

CONCLUSION

APOE-ε2 carriers had a lower percentage of carotid obstruction and less severe stenosis. APOE-ε4 was not related to a higher risk of carotid atherosclerosis in this cross-sectional population-based autopsy study.

The effects of the elastin polymorphisms on carotid intima-media thickness in women aged 30 - 70

[Purpose]

Elastin is one of the major determinants of arterial distensibility of large blood vessels that forms the principal component of elastic fibers from the media of arteries. However, the association between elastin(ELN) genotype and vascular function is still unclear.

[Methods]

120women were recruited from the Saha-gu (Busan, Korea) Community Center. Measurements of body composition and vascular function included carotid intima-media thickness (CIMT), carotid artery luminal diameter (CLD), minimum (diastolic) artery luminal diameter (CLD_min) and maximum (systolic) artery luminal diameter (CLD_max). Genotyping for the ELN (rs 2071307) polymorphism was performed using the TaqMan approach. ELN gene distribution of subjects were in the Hardy-Weinberg equilibrium (p=0.402).

[Results]

The relative CIMT differed significantly among the ELN genotypes. And not significant differences in CLD and CIMT/CLD ratio, but AA genotype was tended higher than other genotypes (AG and GG). The relative CIMT and CLD min differed significantly between the ELN alleles. And not significant differences in CLD max and CIMT/CLD ratio, but A allele was tended higher than G allele.

[Conclusion]

These results suggest that ELN gene polymorphism might be used a one of the genetic determinants of vascular disease in both pre- and postmenopausal women.

Role of 3 lipoprotein lipase variants in triglycerides in children receiving highly active antiretroviral therapy

BACKGROUND

Lipoprotein lipase is a key enzyme in lipid metabolism, especially for plasma triglycerides (TGs). Genetic variants have been associated with lipid levels in healthy individuals, cardiovascular disease, obesity and diabetes. Our aim was to evaluate the influence of 3 polymorphisms: Hind III, Pvu II and S447X in plasma TG levels in human immunodeficiency virus-1-infected children under highly active antiretroviral therapy (HAART).

METHODS

Fifty-two children diagnosed with human immunodeficiency virus-1 between 2005 and 2009 were retrospectively selected with at least 1 plasma TG level assessment. TG levels were examined before and after 1 year of HAART. Hypertriglyceridemia was defined as TG > 150 mg/dL. Hind III (H+/H-), Pvu II (P+/P-) and S447X (S/X) were determined by polymerase chain reaction and restricted fragment length polymorphism. The Wilcoxon sum-rank test was used to compare median plasma TG among groups. Also, allelic frequencies were estimated for these variants in an Argentinean population.

RESULTS

Allelic frequencies for human immunodeficiency virus-1-infected children were: H-, 0.21; P-, 0.53; and X, 0.05 with no significant differences to controls. After 1 year of HAART, median TG levels were significantly lower in P-/P- (98.5 mg/dL) when compared with P+/P+ (180 mg/dL) (P = 0.039). The presence of the P- allele was associated with an 11-fold lower risk of hypertriglyceridemia. Hind III and S447X were not associated with TG at the selected time points.

CONCLUSIONS

Our findings suggest a protective effect of lipoprotein lipase polymorphisms against hypertriglyceridemia in children after 1 year of HAART. These results could endorse a prompt nutritional or pharmacological intervention in patients lacking the P- allele.

APOE polymorphism and carotid atherosclerosis in Korean population: the Dong-gu Study and the Namwon Study

OBJECTIVE

We evaluated the association between APOE polymorphism and carotid atherosclerosis in two large independent cohorts from South Korea.

METHODS

The datasets were from the Dong-gu Study (N = 9056) and the Namwon Study (N = 10,158). Carotid ultrasonography was performed to measure carotid intima-media thickness (IMT) and the presence of carotid plaques. The APOE polymorphism was determined by PCR-RFLP. We performed combined and separate analyses for the two datasets.

RESULTS

In the combined analysis, individuals with E2E2 or E2E3 genotype had a lower common carotid IMT compared with individuals with E3E3 genotype (0.684 mm vs. 0.736 mm, p = 0.007; 0.718 mm vs. 0.736 mm, p < 0.001, respectively). This association was very slightly attenuated but remained statistically significant after adjustment for blood lipids (0.690 mm vs. 0.736 mm, p = 0.033; 0.725 mm vs. 0.736 mm, p = 0.005, respectively). Compared with individuals with E3E3 genotype, individuals with E2E3 genotype had lower risk for carotid plaque (odds ratio (OR) = 0.83, 95% confidence interval (CI) = 0.75-0.93), while individuals with E3E4 genotype had a higher risk for carotid plaque (OR = 1.09, 95% CI = 1.00-1.20). After adjustment for blood lipids, ORs of E2E3 genotype for carotid plaque was slightly attenuated but remained significant (OR = 0.87 95% CI = 0.78-0.97), while OR of E3E4 genotype were slightly attenuated and not significant (OR = 1.08, 95% CI, 0.99-1.18).

CONCLUSIONS

We found that APOE polymorphism is associated with carotid atherosclerosis and this association was partly mediated through blood lipid. Our results suggest that APOE polymorphism may influence atherosclerosis through non-lipid pathways.

Epistatic study reveals two genetic interactions in blood pressure regulation

Background

Although numerous candidate gene and genome-wide association studies have been performed on blood pressure, a small number of regulating genetic variants having a limited effect have been identified. This phenomenon can partially be explained by possible gene-gene/epistasis interactions that were little investigated so far.

Methods

We performed a pre-planned two-phase investigation: in phase 1, one hundred single nucleotide polymorphisms (SNPs) in 65 candidate genes were genotyped in 1,912 French unrelated adults in order to study their two-locus combined effects on blood pressure (BP) levels. In phase 2, the significant epistatic interactions observed in phase 1 were tested in an independent population gathering 1,755 unrelated European adults.

Results

Among the 9 genetic variants significantly associated with systolic and diastolic BP in phase 1, some may act through altering the corresponding protein levels: SNPs rs5742910 (P_adjusted≤0.03) and rs6046 (P_adjusted =0.044) in F7 and rs1800469 (P_adjusted ≤0.036) in TGFB1; whereas some may be functional through altering the corresponding protein structure: rs1800590 (P_adjusted =0.028, SE=0.088) in LPL and rs2228570 (P_adjusted ≤9.48×10^-4) in VDR. The two epistatic interactions found for systolic and diastolic BP in the discovery phase: VCAM1 (rs1041163) * APOB (rs1367117), and SCGB1A1 (rs3741240) * LPL (rs1800590), were tested in the replication population and we observed significant interactions on DBP. In silico analyses yielded putative functional properties of the SNPs involved in these epistatic interactions trough the alteration of corresponding protein structures.

Conclusions

These findings support the hypothesis that different pathways and then different genes may act synergistically in order to modify BP. This could highlight novel pathophysiologic mechanisms underlying hypertension.

The effects of apoA-I/C-III/A-IV, apoE and apoB polymorphisms on carotid artery intima-media thickness

Different apolipoprotein combinations explain most of the functional differences between plasma lipoproteins. This emphasizes the pivotal role of apolipoproteins in the homeostasis and physiological control of lipid metabolism. Genetic polymorphisms of apolipoprotein (apo)A-I/C-III/A-IV, apoE and apoB have been suggested to modulate plasma lipid levels as well as the risk of coronary artery disease and stroke. Carotid artery intima-media thickness has been shown to represent preclinical atherosclerosis and has, therefore, been used as a surrogate in quantifying the early stages of atherosclerosis. The effects of the polymorphisms in apoA-I/C-III/A-IV and apoB on carotid intima-media thickness are poorly known. The corresponding influence of apoE polymorphisms has been studied more extensively, but the results are not yet conclusive. In this review, these results are presented in detail and the potential reasons and mechanisms for the discrepancies are discussed.

Polymorphisms of the methylenetetrahydrofolate reductase, vascular endothelial growth factor, endothelial nitric oxide synthase, monocyte chemoattractant protein-1 and apolipoprotein E genes are not associated with carotid intima-media thickness

BACKGROUND

Single nucleotide polymorphisms in the 5,10-methylenetetrahydrofolate reductase (MTHFR), vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), monocyte chemoattractant protein-1 (MCP-1) and apolipoprotein E (ApoE) genes appear to be a genetic risk factor for atherosclerosis. Common carotid intima-media thickness (cIMT) provides information on the severity of atherosclerosis.

OBJECTIVE

To investigate the relationship between cIMT and gene polymorphisms associated with atherosclerosis in Turkish patients with coronary artery disease (CAD).

METHODS

Sixty-two patients with angiographically diagnosed stable CAD were divided into two groups according to their cIMT values (group 1: n=35, cIMT of 1 mm or greater; group 2: n=27, cIMT of less than 1 mm). MTHFR 677 C/T, VEGF --460 C/T, eNOS 894 G/T, MCP-1 --2518 A/G and ApoE (E2, E3 and E4) gene polymorphisms (where A is adenine, C is cytosine, G is guanine and T is thymine) were analyzed by polymerase chain reaction and restriction fragment length polymorphism. Evaluations of cardiovascular risk factors and coronary atherosclerotic lesions were performed in all patients. Serum homocysteine and high-sensitivity C-reactive protein were measured and compared between the two groups.

RESULTS

Serum high-sensitivity C-reactive protein (P=0.04) and homocysteine (P=0.006) levels were higher in group 1 than in group 2. The ratio of multivessel CAD and previous myocardial infarction was significantly higher in group 1 than in group 2 (P=0.014). In the study population, no significant difference in cIMT was observed according to the polymorphisms studied. Only hyperhomocysteinemia (OR 1.17 [95% CI 1.01 to 1.35], P=0.033) and previous myocardial infarction (OR 3.76 [95% CI 1.10 to 12.81], P=0.034) maintained a significant correlation with cIMT on multiple logistic regression analysis.

CONCLUSION

cIMT is increased in patients with hyperhomocysteinemia, inflammation and extended CAD. MTHFR 677 C/T, VEGF --460 C/T, eNOS 894 G/T, MCP-1 --2518 A/G and ApoE single nucleotide polymorphisms were not associated with increased cIMT.

The STANISLAS Cohort: a 10-year follow-up of supposed healthy families. Gene-environment interactions, reference values and evaluation of biomarkers in prevention of cardiovascular diseases

The description of this familial longitudinal cohort was published in this journal 10 years ago, in 1998. To date, 117 publications on the STANISLAS Cohort (SC) have appeared, corresponding to five main categories of results: familial resemblance and heritability; genetics and gene-environment interactions; mRNA and proteins as gene products; reference values and biological variations of proteins; and finally preventive medicine and prepathological epidemiological data. More than 600 data values on demographic and laboratory data have been collected on each individual taking part out of the 1006 families at the beginning and for all three recruitments. Serum and plasma are stored in liquid nitrogen for all participants for all three recruitments. DNA has been extracted from all participants and mRNA from 357 families. They are stored at -80 degrees C. Owing to the SC study, heritability and many gene-environment interactions have been described. The expression of 166 genes related to cardiovascular diseases was measured in peripheral blood mononuclear cells RNA. Reference values for proteins and vitamins have been established in addition to reference values for the carotid and femoral intima media thickness in adults and children. The data obtained contribute to a better understanding of the relation between the studied polymorphisms (161 polymorphic sites) and health, and predisposition to obesity, high blood pressure and metabolic syndrome. To the best of our knowledge, the SC study is internationally the only longitudinal family cohort of subjects who are presumed to be healthy, which enables the study of the chain DNA-RNA-proteins.

Association between apolipoprotein E genotype and carotid intima-media thickness may suggest a specific effect on large artery atherothrombotic stroke

BACKGROUND AND PURPOSE

Apolipoprotein E genotype (APOE) influences cholesterol levels and ischemic heart disease. Although there is no convincing overall association with ischemic stroke, APOE may influence large artery (atherothrombotic) stroke, for which carotid intima-media thickness (CIMT) is an informative intermediate phenotype. We therefore performed a systematic review and meta-analysis of the association between APOE and CIMT.

METHODS

We sought all published studies assessing the association between APOE and CIMT. From each study, we extracted available data on study methods, subjects' characteristics, and mean (and standard deviation) CIMT for each genotype or genotype group. We calculated study-specific and random effects pooled differences in mean CIMT between genotype groups, and assessed heterogeneity between studies and predefined subgroups using I(2) and chi(2) statistics.

RESULTS

Meta-analysis of 22 published studies (30,879 subjects) showed a significant association between APOE and CIMT (pooled mean difference epsilon 4- versus epsilon 2-allele containing genotypes 46 microm, 95% CI 29 to 62, P<0.00001). We found evidence of small study (mainly publication) bias, with a diminished (but still highly statistically significant) association in studies of >1000 subjects (pooled mean difference 17 microm, 95% CI 12 to 23, P<0.00001). The association was larger among high vascular risk and eastern Asian populations, but this may simply reflect the smaller size of these studies.

CONCLUSIONS

Our results show a clear association of APOE with CIMT, even though publication bias means that this is overestimated by the published literature. These findings suggest the possibility of a specific association with large artery ischemic stroke.

A common VLDLR polymorphism interacts with APOE genotype in the prediction of carotid artery disease risk

The genetic factors associated with carotid artery disease (CAAD) are not fully known. Because of its role in lipid metabolism, we hypothesized that common genetic variation in the very low density lipoprotein receptor (VLDLR) gene is associated with severe CAAD (>80% stenosis), body mass index (BMI), and lipid traits in humans. VLDLR was resequenced for variation discovery in 92 subjects, and single nucleotide polymorphisms (tagSNPs) were chosen for genotyping in a larger cohort (n = 1,027). Of the 17 tagSNPs genotyped, one tagSNP (SNP 1226; rs1454626) located in the 5' flanking region of VLDLR was associated with CAAD, BMI, and LDL-associated apolipoprotein B (apoB). We also identified receptor-ligand genetic interactions between VLDLR 1226 and APOE genotype for predicting CAAD case status. These findings may further our understanding of VLDLR function, its ligand APOE, and ultimately the pathogenesis of CAAD in the general population.

Folate and ApoE DNA Methylation Induced by Homocysteine in Human Monocytes

Homocysteine (Hcy) is an important and independent risk factor for arteriosclerosis, and apolipoprotein E (ApoE) is an important gene of anti atherosclerosis, but the characteristics and their key links that are involved in their pathogenic mechanisms are still poorly understood. The objective of the present study was to investigate the effects of Hcy and folate on ApoE as well as the underlying mechanism of ApoE expression induced by Hcy in monocytes. When clinically relevant concentrations of Hcy and folate were added to the cultured monocytes for 4 days, we found that clinically relevant Hcy (100 microM) may increase the levels of total cholesterol (TC), free cholesterol (FC), and cholesteryl ester (CE), and also decrease ApoE mRNA, protein expressions, leading to 34.28%, 45.00% in cultured primary human monocytes in comparison to the positive group. The effects of Hcy were primarily mediated by C-5 MTase, because Hcy could upregulate the activity of C-5 MTase and then accelerate DNA methylation of ApoE. However, folate decreased the levels of TC, FC, and CE (p < 0.001) and increased the ApoE expression; as to say, folate primarily repressed the effects of DNA methylation induced by Hcy and reduced anti atherosclerosis. In conclusion, these results suggested that ApoE DNA methylation that is induced by Hcy may play a potential role for ApoE expression in atherosclerosis. Folate has beneficial effects for anti atherosclerosis, and it may become a therapeutic target for preventing Hcy-induced atherosclerosis.

Apolipoprotein E epsilon4 genotype is independently associated with increased intima-media thickness in a recessive pattern

Polymorphisms in the apolipoprotein E (Apo E) gene have been associated with lipid levels, carotid intima media thickness (CCA-IMT), inflammation and cardiovascular disease (CVD). Earlier findings suggested an association of the Apo E alleles with increased CCA-IMT following a recessive pattern. Whether associations might be independent of C-reactive protein (CRP), lipid levels and other CVD risk factors is not known. We investigated the relationships between Apo E (epsilon2, epsilon3 and epsilon4 alleles) and CCA-IMT, measured by B-mode ultrasound, in dominant and recessive models in a community-based sample of 437 men 75 years of age. In men homozygous for the epsilon4 allele CCA-IMT was significantly increased by 0.13 mm to 0.86 +/- 0.16 mm compared to 0.73 +/- 0.19 mm in non- epsilon4-carriers (P = 0.0012) and 0.73 +/- 0.21 mm in epsilon4 heterozygous (P = 0.0044) in unadjusted recessive models. The association between Apo E epsilon4 genotype and CCA-IMT was independent of Apo E epsilon2 and Apo E epsilon3 alleles, CRP, lipid variables (TG, LDL, HDL) and other CVD risk factors (smoking, hypertension, body mass index, diabetes) (P = 0.018). No relations between Apo E genotype and CCA-IMT were observed in dominant models. No significant associations between the Apo E epsilon2 and epsilon3 alleles and CCA-IMT were found. In this study, men homozygous with the ApoE epsilon4 allele had thicker CCA-IMT, independently of Apo E epsilon2 and epsilon3 alleles, CRP, lipid variables (TG, LDL, HDL) and other CVD risk factors (smoking, hypertension, body mass index, diabetes), suggesting CCA-IMT to be modified by the ApoE epsilon4 genotype in a recessive pattern.

Evaluation of cardiovascular risk factors and related clinical markers in healthy young Japanese adults

BACKGROUND

Since atherosclerosis is a slowly progressive process at a young age, effective preventive measures should be taken early in life to prevent future events associated with cardiovascular disease.

METHODS

The study population comprised 132 young Japanese adults (mean age 21.4 years, range 18-31 years). We screened plasma total homocysteine and serum folate levels and evaluated mean carotid intima-media thickness and cardio-ankle vascular index.

RESULTS

Multiple regression analysis after adjustment for age and sex revealed that only folate levels were significantly correlated with plasma total homocysteine levels (beta=-0.37, p=0.028). Carotid intima-media thickness adjusted for age and sex and compared between quintiles of total homocysteine levels was significantly increased in the highest quintile compared with other quintiles. Cardio-ankle vascular index increased with age in both women and men, but no additional determinants were identified in young adults.

CONCLUSION

Serum folate is an independent determinant of plasma total homocysteine levels, and mild hyperhomocysteinemia may represent a risk factor for increased carotid intima-media thickness, even in young adults. Comprehensive health education from the early period of life, including the suggestion of appropriate dietary measures, is important for effective prevention of future atherosclerosis.

New Insight Into the Association of Apolipoprotein E Genetic Variants With Carotid Plaques and Intima-Media Thickness

BACKGROUND AND PURPOSE

Carotid plaques and elevated carotid artery intima-media thickness (IMT) are major predictors of vascular morbidity and mortality. Our aim was to test their association with 2 polymorphisms of the apolipoprotein E (apoE) gene, epsilon and -219G/T.

METHODS

The study was performed on 5856 subjects aged > or =65 years recruited from the French population for the Three-City Study. Carotid ultrasound examination included an assessment of atherosclerotic plaques in the extracranial carotid arteries and a measurement of IMT in the common carotid arteries (CCA) at a site free of plaques. The genetic association was tested using genotype and haplotype analyses.

RESULTS

In a multivariate analysis including both polymorphisms and vascular risk factors, carotid plaques were more frequent in epsilon4 homozygotes (adjusted odds ratio=2.12, 95% CI=1.27 to 3.53) and less frequent in epsilon2 carriers (adjusted odds ratio=0.79, 95% CI=0.66 to 0.95) compared with epsilon3 homozygotes. Adjusting for and stratifying on lipid levels did not modify these results. CCA-IMT was higher in carriers of the epsilon34 genotype (mean CCA-IMT=0.744 mm versus 0.732 mm for the epsilon33 genotype, P=0.002), but the association disappeared after excluding subjects with carotid plaques. No association was found between the -219 polymorphism and either carotid plaques or CCA-IMT, and there was no interaction or cis-effect between -219 and epsilon.

CONCLUSIONS

This study, conducted on a large population cohort of French elderly, demonstrated that carotid plaques were significantly associated with the apoE epsilon polymorphism independently of the -219 polymorphism and vascular risk factors, in particular lipid levels.

Lipoprotein lipase S447X: a naturally occurring gain-of-function mutation

Lipoprotein lipase (LPL) hydrolyzes triglycerides in the circulation and promotes the hepatic uptake of remnant lipoproteins. Since the gene was cloned in 1989, more than 100 LPL gene mutations have been identified, the majority of which cause loss of enzymatic function. In contrast to this, the naturally occurring LPL(S447X) variant is associated with increased lipolytic function and an anti-atherogenic lipid profile and can therefore be regarded as a gain-of-function mutation. This notion combined with the facts that 20% of the general population carries this prematurely truncated LPL and that it may protect against cardiovascular disease has led to extensive clinical and basic research into this frequent LPL mutant. It is only until recently that we begin to understand the molecular mechanisms that underlie the beneficial effects associated with LPL(S447X). This review summarizes the current literature on this interesting LPL variant.

Relations of APOE promoter polymorphisms to LDL cholesterol and markers of subclinical atherosclerosis in young adults

The common apolipoprotein E (apoE) gene (APOE) epsilon2/epsilon3/epsilon4 polymorphism explains part of serum lipid variation, and polymorphisms in the APOE promoter region have been proposed to participate in the regulation of serum lipid levels within the most common APOE epsilon3/epsilon3 genotype group. We determined APOE -219G/T and +113G/C promoter genotypes and estimated APOE haplotypes in 525 participants of the Cardiovascular Risk in Young Finns Study. We studied the associations of the APOE promoter polymorphisms and their haplotypes with cross-sectional and longitudinal serum lipid and apolipoprotein concentrations as well as with flow-mediated dilatation (FMD), carotid artery compliance (CAC), and intima-media thickness (IMT) within the APOE epsilon3/epsilon3 carriers. We found no significant association between the APOE promoter genotypes and serum lipids [low density lipoprotein-cholesterol (LDL-C), HDL-C, and triglycerides], apolipoproteins (apoA-I and apoB), or brachial artery FMD, CAC, or carotid IMT in either men or women. In longitudinal analyses in males, the carriers of heterozygous genotypes (-219G/T or +113G/C) and, furthermore, carriers of the -219T/+113C/epsilon3 haplotype had significantly higher LDL-C and total cholesterol concentrations throughout the 21 year follow-up period compared with homozygous G allele carriers or noncarriers of the -219T/+113C/epsilon3 haplotype. Such associations were not found in females. In summary, the APOE promoter polymorphisms -219G/T and +113G/C as well as their haplotype are associated with longitudinal changes in LDL-C and total cholesterol concentrations in young Finnish males but do not seem to be major determinants for FMD, CAC, or carotid IMT in males or females.

Genetic determinants of blood pressure regulation

Hypertension is a multifactorial disorder that probably results from the inheritance of a number of susceptibility genes and involves multiple environmental determinants. Existing evidence suggests that the genetic contribution to blood pressure variation is about 30-50%. Although a number of candidate genes have been studied in different ethnic populations, results from genetic analysis are still inconsistent and specific causes of hypertension remain unclear. Furthermore, the abundance of data in the literature makes it difficult to piece together the puzzle of hypertension and to define candidate genes involved in the dynamic of blood pressure regulation. In this review, we attempt to highlight the genetic basis of hypertension pathogenesis, focusing on the most important existing genetic variations of candidate genes and their potential role in the development of this disease. Our objective is to review current knowledge and discuss limitations to clinical applications of genotypic information in the diagnosis, evaluation and treatment of hypertension. Finally, some principles of pharmacogenomics are presented here along with future perspectives of hypertension.

Association of APOE genotype with carotid atherosclerosis in men and women

The aim of this study was to determine the association between APOE genotype and carotid atherosclerosis, defined as intimal-medial thickness (IMT) and stenosis, and to assess if other cardiovascular risk factors modify this association. A total of 1,315 men and 1,408 women from the Framingham Offspring Study underwent carotid ultrasound during examination cycle 6 and had complete data on APOE genotype. Three APOE genotype groups were defined: APOE2 (including E2/E2, E3/E2 genotypes), APOE3 (E3/E3), and APOE4 (including E4/E3, E4/E4 genotypes). Carotid IMT and the presence of carotid stenosis > 25% were determined by ultrasonography. In women, the APOE2 group was associated with lower carotid IMT (0.67 vs. 0.73 mm) and lower prevalence of stenosis (odds ratio = 0.49; 95% confidence interval = 0.30-0.81) compared with the APOE3 group. In men, APOE genotype was not associated with carotid IMT or stenosis in the whole group; however, diabetes modified the association between APOE genotype and carotid IMT (P for interaction = 0.044). Among men with diabetes, the APOE4 group was associated with a higher internal carotid artery IMT (1.22 mm) than the APOE3 group (0.90 mm) or the APOE2 group (0.84 mm). The E2 allele was associated with lower carotid atherosclerosis in women, and the E4 allele was associated with higher internal carotid IMT in diabetic men.

Genetics of Ultrasonographic Carotid Atherosclerosis

The search for genes related to the cause of common complex disorders such as cardiovascular disease has been frustrating, partly because of the many factors known to contribute to cardiovascular disease and the potential "distance" of cardiovascular disease as a phenotype from genes and gene products. Linkage and association studies for phenotypes more proximal in the pathway from DNA sequence variation to overt clinical disease, such as ultrasound-defined carotid atherosclerosis, may potentially be more enlightening. Only one genetic variant previously reported to be associated with atherosclerosis or clinically evident cardiovascular disease, matrix metalloproteinase (MMP) 3, has shown consistently positive associations with carotid disease, although it has not been studied widely. Another, PON1 L55M, is weakly associated in subgroups only, and 2, ApoE and MTHFR, are equivocal. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis. This may reflect the known inconsistency in associations of genetic variants with clinical cardiovascular disease itself. Alternatively, genetic determinants of ultrasound-defined carotid atherosclerosis may differ from those of clinically manifest cardiovascular disease and may require pursuit through large-scale genomic studies of carotid atherosclerosis as a distinct phenotype. Only 1 genetic variant, MMP 3, has shown consistently positive associations with ultrasonographic carotid disease, although it has not been studied widely. Another, PON1 L55 mol/L, is weakly associated in subgroups only. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis.

Apolipoprotein E polymorphism and carotid atherosclerosis in patients with coronary disease

BACKGROUND

Apolipoprotein (apo) E polymorphism plays a role in the development of coronary disease, but their involvement in carotid atherosclerosis is controversial. The aim of this study was to evaluate the role of apo E polymorphism in the development of subclinical carotid atherosclerosis in patients with coronary disease.

METHODS

In 226 consecutive patients with coronary disease, apo E genotypes were performed by PCR and restriction analysis. Intima-media thickness (IMT) and the presence of atherosclerotic plaques in carotid arteries were evaluated by two-dimension ultrasonography.

RESULTS

Apo E allele frequencies were: 3=0.70, 4=0.22 and 2=0.08. The only patient with 2/4 genotype was excluded for the analysis. The patients were divided in three groups according to apo E genotype: E2 (2/2, 2/3), E3 (3/3) and E4 (4/4, 4/3). Patients of E4 group had higher values of low-density-lipoprotein (LDL) cholesterol and apo B than patients of E2 group (P< or =0.01). Carotid IMT mean was not different in E3 (0.81+/-0.21 mm), E4 (0.83+/-0.23 mm) and E2 groups (0.76+/-0.17 mm) (P=0.52). Mean differences of IMT in E3 group were not different from those of E2 or E4 groups after adjusting for age and gender in a first analysis, and for age, gender and LDL cholesterol levels in a second one. The number of plaques in apo E3 group was similar to that in apo E2 or apo E4 groups, after adjusting for the same variables.

CONCLUSIONS

A relationship between subclinical carotid atherosclerosis and apo E polymorphism is not found in patients with coronary disease.

Genetic risk factors for stroke and carotid atherosclerosis: insights into pathophysiology from candidate gene approaches

Ischaemic stroke is the most common form of stroke and is caused by atherosclerosis in most patients. Several genetic determinants contribute to stroke risk. Of these, carotid intimal-medial wall thickness (IMT) is particularly relevant, because it is a surrogate measure of subclinical atherosclerosis and a strong predictor of future ischaemic stroke. Studies of twins, siblings, and families have provided significant evidence for heritability, but the genes involved have not been identified. Some researchers have reported that IMT is high in people with functional variants of genes related to matrix deposition (MMP3), inflammation (interleukin 6), and lipid metabolism (hepatic lipase, APOE, CETP, and PON1). In this review, we assess the robustness of these associations and examine whether there is any evidence of risk modification by factors, such as smoking.

A study of gene--environment interaction on the gene for angiotensin converting enzyme: a combined functional and population based approach

INTRODUCTION

Studies on the role of the insertion/deletion (I/D) polymorphism of the gene coding for angiotensin converting enzyme (ACE) in atherosclerosis have been inconsistent. In a meta-analysis, we recently showed that this relationship is stronger in high risk populations. In this paper, we used a combined functional and population based approach to investigate the gene-environment interaction of the ACE I/D polymorphism in relation to carotid artery wall thickness.

METHODS

The study was part of the Rotterdam Study, a prospective population based cohort study. In 5321 subjects, IMT was measured in the carotid arteries by ultrasonography and ACE genotype was determined by size analysis of polymerase chain reaction products.

RESULTS

In multiple regression analysis, I/D polymorphism and smoking were the main determinants for plasma ACE activity (r(2) = 0.28). There was a positive association between the D allele of the I/D polymorphism and carotid artery thickness among current smokers (p = 0.03). Subjects carrying only one of the risk factors (smoking or the D allele) did not show significant differences in IMT compared with the non-/former smokers group carrying two II alleles, while carriers of both risk factors had significant higher IMT. The association was not present in non-/former smokers.

DISCUSSION

The results provide further evidence that genetic and environmental factors interact in the formation of the arterial lesions. This study shows that large population based studies can be extremely helpful in unravelling the genetic origin of complex diseases such as atherosclerosis.

The role of cardiovascular risk factors in Alzheimer's disease

The distinction between Alzheimer's disease and vascular dementia, the two most common types of dementia, has been undermined by recent advances in epidemiologic, clinical, imaging, and neuropathological studies. Cardiovascular risk factors, traditionally regarded as distinguishing criteria between the two entities, have been shown to be associated with both AD and vascular dementia. In this article, we propose mechanisms of action of cardiovascular risk factors in AD, suggest possible explanations for the overlap with vascular dementia and discuss the implications this might have on future differential diagnosis, research, and treatment strategies.

Angiotensin-converting enzyme gene polymorphism and carotid artery wall thickness: a meta-analysis

BACKGROUND AND PURPOSE

Many studies have investigated the association between the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and carotid artery intima-media thickness (IMT); however, most studies were small and conducted in selective samples. The aim of this study was to evaluate this association by performing a meta-analysis on published articles.

METHODS

We searched Medline for articles studying the association between the ACE I/D polymorphism and carotid IMT. Twenty-six studies were found; 23 articles containing 9833 subjects were qualified to enter the meta-analysis. We classified those articles on the basis of their samples into high-risk and low-risk populations and white and Asian ethnic groups. IMT was used as a continuous variable, and data were analyzed with the Cochrane Review Manager.

RESULTS

A significant positive association was present between the D allele and common carotid IMT (weighted mean difference between DD and II genotypes, 0.23 mm x 10(-1); P<0.01). The association was stronger among high-risk populations. The point estimates of DD versus II were higher than those of ID versus II.

CONCLUSIONS

Our meta-analysis showed evidence of a positive association between the D allele of the ACE gene and common carotid IMT. The overall results were concordant in both ethnic groups.

Apolipoprotein E gene polymorphisms are associated with carotid plaque formation but not with intima-media wall thickening: results from the Perth Carotid Ultrasound Disease Assessment Study (CUDAS)

BACKGROUND AND PURPOSE

Several studies have investigated the role of apolipoprotein E (apoE) polymorphisms on carotid intima-media thickness (IMT) with conflicting results. The objective of this study was to use a large, community-based population to investigate associations between apoE gene polymorphisms and cardiovascular disease-associated phenotypes: IMT, carotid artery plaque, and low- (LDL-C) and high-density lipoprotein cholesterol (HDL-C).

METHODS

ApoE genotypes were determined in 1109 randomly selected community subjects with an equal man-to-woman ratio and equal numbers in each age decile who were 27 to 77 years of age and had bilateral carotid B-mode ultrasound and cardiovascular risk factor measurements.

RESULTS

Multivariate analyses, stratified by sex, demonstrated an association between apoE genotypes and LDL-C levels in men (P=0.03) and women (P<0.001). A significant linear trend in increasing LDL-C (beta=0.33 per unit change in genotype; SE=0.07; P<0.001) levels with increasing number of epsilon4 alleles across the epsilon3/epsilon3, epsilon3/epsilon4, or epsilon4/epsilon4 genotypes was observed in women but not in men. The associations were independent of age, diastolic blood pressure, and history of diabetes mellitus. Multivariate analyses found a log-additive trend in risk of developing carotid plaque with increasing numbers of epsilon4 alleles across the epsilon3/epsilon3, epsilon3/epsilon4, and epsilon4/epsilon4 genotypes (odds ratio [OR], 1.72 per unit change in genotype; 95% CI, 1.05 to 2.80; P=0.03) in men. There was no association between plaque frequency and the epsilon4 allele in women. However, the epsilon2/epsilon3 genotype was shown to be associated with a lower OR (OR, 0.40; 95% CI, 0.17 to 0.91; P=0.03) for carotid plaques relative to the epsilon3/epsilon3 genotype in women. The associations were independent of age and standard vascular risk factors. There were no significant independent associations between apoE genotypes and IMT in either men or women.

CONCLUSIONS

Our data suggest that polymorphisms in the apoE gene are significantly associated with LDL-C levels and increased risk of carotid plaque formation in men but not IMT in either men or women.

Effect of six candidate genes on early aging in a French population

BACKGROUND AND AIMS

The objective of this study was to examine the association between an aging indicator previously defined from a nationwide population study, and lipids and apolipoproteins, angiotensin converting enzyme, paraoxonase activities, and six candidate genes related to the aging process.

METHODS

Two hundred and fifty-six healthy Caucasian men (69.8 +/- 4.0 years) were included in the study. Total cholesterol, triglycerides, HDL-cholesterol, lipoprotein(a), apolipoprotein A1, B and E concentrations, and the activities of paraoxonase, arylesterase, and angiotensin-converting enzymes were determined by standardized laboratory methods. A multiplex assay was used to genotype the studied polymorphisms: apolipoprotein E, lipoprotein lipase, paraoxonase, methylenetetrahydrofolate reductase, cystathionine beta-synthase and angiotensin-converting enzymes.

RESULTS

Paraoxonase polymorphism at codon 192 (Gln/Arg) was the only one significantly associated with the aging indicator, Gln homozygotes being more advanced in aging compared with Arg allele carriers. It was also observed that the aging indicator was positively correlated with serum concentrations of total cholesterol, triglycerides and apolipoprotein B, and negatively with the activities of basal and stimulated paraoxonase and arylesterase. Multiple regression analysis showed that triglycerides and basal paraoxonase activity explain 13.6% of the variance of the aging indicator.

CONCLUSIONS

Triglyceride concentration and paraoxonase gene and activities may contribute to the aging process. Taking into account the smallness of the sample size, and the poor level of significance due to the im-plication of paraoxonase polymorphism at codon 192, these results need to be verified in further studies on a greater number of subjects.

Apolipoprotein E polymorphism affects carotid artery atherosclerosis in smoking hypertensive men

OBJECTIVE

Smoking is a risk factor for increased carotid artery intima-media thickness (IMT). The apolipoprotein E (apoE) 4 allele has been associated with cardiovascular diseases, but the role of apoE in regard to intima-media thickness (IMT) has remained controversial. The objective was to investigate whether there is some gene-environment interaction between smoking and apoE polymorphism. DESIGN Cross-sectional case-control study.

METHODS

IMTs of 511 hypertensive and control men were measured ultrasonographically and the apoE genotypes were determined. Genotypes with the 4 allele were pooled into one group and the genotypes without it into another.

RESULTS

A significant interaction between the 4 allele and smoking affecting IMT was observed among the hypertensive smokers, as assessed by analysis of covariance. The mean carotid IMT was significantly greater (1.01 versus 0.90 mm, P = 0.003) in the 4 carriers than in the subjects without 4 among the hypertensive smokers. The number of plaques was also significantly higher. No differences were found in the other subjects (hypertensive non-smokers or controls). Linear regression analysis indicated that the 4 allele was an independent determinant of IMT in the hypertensive smokers but not in the other subjects. The estimated average effect of the 4 allele on the mean IMT in the hypertensive smokers was 0.088 mm (P < 0.001). In the oldest age group, the interaction of smoking and 4 was also seen in the control subjects.

CONCLUSION

The findings suggest that the 4 carriers are particularly susceptible to the atherogenic effects of smoking. This interaction is particularly clear in hypertensive subjects.

An interaction between systolic blood pressure and angiotensin-converting enzyme gene polymorphism on carotid atherosclerosis

The insertion/deletion (I/D) polymorphism of the human angiotensin-converting enzyme (ACE) gene is a major determinant of circulating ACE activity, with the D allele being associated with higher ACE levels than the I allele. Thus, chronic exposure to high levels of circulating and tissue ACE may well predispose to vascular wall thickening and atherosclerosis. However, the effect of the ACE gene on carotid atherosclerosis remains controversial. We investigated the association between ACE gene I/D polymorphism and risk factor-dependent augmentation of carotid arterial remodeling in subjects with several risk factors for atherosclerosis. We evaluated sclerotic lesions of the common carotid artery with intima-media thickness (IMT) by ultrasonography in 184 patients (mean age +/- SD, 67 +/- 14 years old) and studied whether any risk factor-gene interactions were associated with carotid atherosclerosis. Out of the 184 subjects, 71 had the ACE II genotype, 87 the ID genotype and 26 the DD genotype. There was no significant difference in IMT among the three ACE genotypes. In total subjects, multiple regression analysis showed that age, total-cholesterol (T-C), and HDL-cholesterol (HDL-C) were significantly associated with IMT. However, the association between risk factors and IMT was genotype-specific. Systolic blood pressure (SBP) and HDL-C were significantly associated with IMT in ACE D carriers (DD+ID), but not in subjects with the ACE II genotype. Similarly, T-C was significantly associated with IMT only in subjects with the ACE II genotype. A general linear model of the interaction between the ACE genotype and the conventional risk factors showed that the SBP-ACE genotype interaction were significantly associated with IMT (F = 7.915; p = 0.005). This finding further supports the idea that analysis of risk factor-gene interaction could be a useful tool for deriving specific predictive information about the development of atherosclerosis.

Family studies: their role in the evaluation of genetic cardiovascular risk factors

Early epidemiological studies showed that genetic factors contribute to the risk of cardiovascular disease. Genetic epidemiological studies based upon families can be used to investigate familial trait aggregation, to localize genes implicated in cardiovascular diseases in the human genome, and to establish the role of environmental factors. Family studies can be also used to identify the physiological role of candidate genes for cardiovascular diseases, and to characterize shared environmental risk factors and their impact on the expression of genetic predisposition. The present paper reviews the existing family studies with special emphasis on those which have studied healthy populations in relation to cardiovascular disease such as the Framingham Heart Study, the National Heart, Lung, and Blood Institute Family Heart Study, and the STANISLAS cohort.

Carotid artery intima-media thickness and brachial artery flow-mediated vasodilation in asymptomatic Japanese male subjects amongst apolipoprotein E phenotypes

BACKGROUND

Epidemiological studies suggest that apolipoprotein E (apoE) polymorphism influences plasma lipoprotein levels and the development of cardiovascular disease.

OBJECTIVE

To clarify the role of apoE polymorphism as a risk factor for early atherosclerosis.

DESIGN

Using a high-resolution ultrasound method, we investigated the association between apoE phenotypes, carotid intima-media thickness (CCA-IMT), and flow-mediated dilation in the brachial artery (brachial-FMD) in 96 healthy asymptomatic Japanese men (mean +/- SD age, 50 +/- 8 years).

RESULTS

Serum cholesterol and LDL-cholesterol levels in subjects with E3E4 were highest and those with E2E3 were lowest (P < 0.05 and P < 0.05, respectively). The CCA-IMT in E3E4 subjects (0.76 +/- 0.17 mm) was greater than that in E2E3 and E3E3 (0.61 +/- 0.15 and 0.64 +/- 0.14 mm, respectively; P < 0.01). In contrast, there was no difference between brachial-FMD and apoE phenotypes (P=0.15). By univariate analysis, CCA-IMT was positively correlated with age (r=0.51, P < 0.01), LDL-chol/HDL-chol ratio (r=0.37, P < 0.01), triglycerides (r=0.23, P < 0.05), and negatively correlated with HDL-cholesterol (r=-0.31, P < 0.01). An association between CCA-IMT and the presence of E4 allele was also found (P < 0.05). Logistic regression analysis revealed that the presence of E4 allele was a higher risk for increased IMT (relative risk of 4.4, 95% CI 1.5-12.5), even after adjustment for age, LDL-cholesterol, blood pressure and other known risk factors. A negative correlation between brachial-FMD and CCA-IMT was also found in all subjects (r=-0.21, P < 0.05), being most apparent in the E3E4 subjects (r=-0.53, P < 0.02).

CONCLUSION

ApoE4 phenotype was independently associated with an increased risk of carotid atherosclerosis and elevated LDL-cholesterol levels in asymptomatic middle-aged Japanese men.

Influence of apolipoprotein E, smoking, and alcohol intake on carotid atherosclerosis: National Heart, Lung, and Blood Institute Family Heart Study

BACKGROUND AND PURPOSE

Apolipoprotein E (apoE) isoforms and lifestyle factors play an important role in the development of coronary heart disease. The association of apoE and carotid atherosclerosis remains controversial.

METHODS

We investigated the relation of apoE, cigarette smoking, alcohol drinking, and their interaction with carotid atherosclerosis on 544 individuals free of coronary heart disease in the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study. Atherosclerotic lesions of the carotid arteries were detected through high-resolution ultrasound.

RESULTS

Subjects in the apoE4 group had lower blood pressure, lower high-density lipoprotein cholesterol, and higher low-density lipoprotein cholesterol. In a multivariate logistic regression model, apoE isoforms and alcohol consumption were not significantly associated with the prevalence odds of carotid atherosclerosis (P=0.94 and 0.98, respectively, for trend). In contrast, compared with those who never smoked, the prevalence odds ratios for carotid atherosclerosis were 1.7 [95% confidence interval (CI),1.1 to 2.7], 2.8 (95% CI, 1.2 to 6.2), and 1.9 (95% CI, 0.7 to 5.5) for former smokers, current smokers of 1 to 20 cigarettes per day, and current smokers of >20 cigarettes day, respectively (P=0.0018 for trend). We did not find evidence of an interaction between apoE and alcohol consumption. Our data suggested a synergistic effect between the apoE allele epsilon(4) and smoking on carotid atherosclerosis: odds ratios were 1.7 (95% CI, 0.8 to 3.6) for smoking alone, 1.0 (95% CI, 0.6 to 1.8) for epsilon4 alone, and 3.7 (95% CI, 1.1 to 3.6) for the joint presence of the apoE allele epsilon4 and smoking.

CONCLUSIONS

Smoking but not alcohol consumption or ApoE is associated with an increased odds of carotid atherosclerosis. Our data suggest a synergistic effect between the apoE allele epsilon4 and smoking on carotid atherosclerosis.

APOC3, CETP, fibrinogen, and MTHFR are genetic determinants of carotid intima-media thickness in healthy men (the Stanislas Cohort)

The purpose of this study was to examine the relationship between carotid intima-media thickness (CIMT) inter-individual variability and 16 polymorphisms of 11 genes associated with cardiovascular risk factors (genes among lipid and homocysteine metabolisms, blood viscosity, platelet aggregation, leukocyte adhesion and renin-angiotensin system). CIMT was measured by high resolution B-mode ultrasonography in an healthy population of 77 men and 84 women, aged 35-54 years and selected from a French Cohort: the Stanislas Cohort. The polymorphisms studied were genotyped by a multilocus approach. Statistical analyses were carried out by ANOVA, after adjustment of CIMT for age, body mass index, and smoking, and by multiple regression analyses. No association was found with APOB Thr71Ile, APOC3 -482C/T, -455T/C, GpIIIa P1A, AT1R 1166A/C, AGT Met235Thr, CBS Ile278Thr, SELE 98G/T, and SELE Ser128Arg, polymorphisms neither in men nor in women. Although, in women we did not find any association for APOC3 3206T/G, 3175C/G, 1100C/T, CETP Ile405Val, MTHFR 677C/T and fibrinogen -455G/A polymorphisms; in men these polymorphisms were associated with CIMT variability (p< or =0.01; p< or =0.05). The most interesting finding was that altogether these genes in men were able to explain a considerable part, 20.6%, of CIMT variability. Therefore, our study gives a new opportunity to understand CIMT variability.

Genotype-specific association between circulating soluble cellular adhesion molecules and carotid intima-media thickness in community residents: J-SHIPP study. Shimanami Health Promoting Program

Plasma levels of soluble forms of cellular adhesion molecules (CAMs) and their relationships with carotid intima-media thickness (IMT) were investigated in community residents. Plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured by ELISA in 200 community residents in Japan. Carotid IMT showed a weak but significant positive correlation with the plasma levels of both sICAM-1 (r=0.175, p=0.013) and sVCAM-1 (r=0.19, p=0.0075). Gene polymorphisms of angiotensin converting enzyme (ACE) insertion/deletion (I/D), angiotensinogen (AGT) M235T, angiotensin II type 1 receptor (AT1R) A1166C and apolipoprotein E (apoE) were determined for each subject. The plasma level of sVCAM-1 tended to be lower in subjects with the ACE DD genotype than in those with the ACE ID and II genotypes (373+/-94, 421+/-133, 443+/-135 ng/ml, respectively, p=0.056). However, there were no genotype-specific differences in the plasma levels of soluble forms of CAMs for the other genes examined. In a separate analysis, the plasma level of sICAM-1 was significantly associated with carotid IMT in ACE D carriers (ID + DD) (r=0.28, p=0.002), AGT M carriers (MT + MM) (r=0.32, p=0.0045), and subjects with apoE4 (r=0.35, p=0.036). In contrast, the plasma level of sVCAM-1 showed significant positive correlations with carotid IMT in subjects with the ACE II genotype (r=0.33, p=0.0027) or AGT TT genotype (r= 0.22, p=0.015), and subjects with apoE E2/E3 or E3/E3 (r=0.16, p=0.043). Stepwise regression analysis showed that plasma sVCAM-1 was independently associated with carotid IMT in subjects with the ACE II genotype or apoE4 genotype. Similarly, the plasma level of sICAM-1 was independently associated with carotid IMT in AGT M carriers. These findings suggest that genetic background could be involved in the association between plasma CAMs and atherosclerosis.

The LPL S447X cSNP is associated with decreased blood pressure and plasma triglycerides, and reduced risk of coronary artery disease

Linkage of the lipoprotein lipase (LPL) gene to blood pressure levels has been reported. The LPL S447X single nucleotide polymorphism (cSNP) has been associated with decreased triglycerides (TG), increased high density lipoprotein cholesterol, and a decreased risk of coronary artery disease (CAD), which may occur independently of its beneficial lipid changes. To investigate the relationship between LPL S447X cSNP and these parameters, we studied a cohort of individuals with familial hypercholesterolemia in whom blood pressures and information regarding the use of blood pressure lowering medications were available. Carriers of the S447X variant had decreased TG (1.21+/-0.47 vs. 1.52+/-0.67, p<0.001) and a trend towards decreased vascular disease (12.7 vs. 19.5%) compared to non-carriers. More interestingly, however, carriers of this cSNP had decreased diastolic blood pressure compared to non-carriers (78+/-10 vs. 82+/-11, p=0.002), evident in both men and women, youths and adults, with similar trends for systolic blood pressure. Furthermore, the decrease in blood pressure appeared independent of the decrease in TG (p=0.02), suggesting that the LPL protein may have a direct influence on the vascular wall. This suggests an additional mechanism whereby this variant may have protective effects, independent of changes in plasma lipid levels.

Apolipoprotein E and carotid artery atherosclerosis: the Rotterdam study

BACKGROUND AND PURPOSE

Carotid artery atherosclerosis is a strong predictor for future stroke. It is yet unclear whether the apolipoprotein E polymorphism (APOE) is related to atherosclerosis in the carotid arteries. The aim of the present study was to investigate the role of APOE in carotid artery atherosclerosis.

METHODS

A population-based cross-sectional study was performed on 5401 subjects. Atherosclerosis was noninvasively assessed by the common carotid artery intima-media wall thickness and the presence of plaques in the carotid arteries. The relationship of the 6 APOE genotypes with these 2 indicators was studied with linear and logistic regression analysis, respectively, with adjustments for age and sex.

RESULTS

Carriers of the E2E3 genotype had a thinner intima-media wall thickness (mean difference, -0.02 mm; 95% CI, -0.03 to -0.01 mm) and fewer plaques (odds ratio for >3 plaques at 6 sites, 0.6; 95% CI, 0.4 to 0.8) than the most common group, E3E3. The E4E4 group had slightly more atherosclerosis, but this was not statistically significant. Adjusting for the level of the apolipoprotein E protein (apoE) in serum or total or HDL cholesterol did not essentially change these findings.

CONCLUSIONS

Our results suggest that APOE*4 is not an important risk factor for carotid artery atherosclerosis. The inverse relationship of E2E3 with carotid artery atherosclerosis seems to be independent of serum apoE and total and HDL cholesterol levels. However, the low frequency, together with the small effects, implies that any protective effect of E2E3 on carotid artery atherosclerosis is limited.

Polymorphism of the lipoprotein lipase gene and risk of atherothrombotic cerebral infarction in the Japanese

BACKGROUND AND PURPOSE

Lipid and lipoprotein abnormalities have been implicated in the pathogenesis of ischemic cerebrovascular disease and atherosclerosis. Lipoprotein lipase (LPL) plays an important role in plasma lipoprotein metabolism. Several studies have recently reported the presence of a relationship between Ser447Stop mutation of LPL and coronary artery disease. Other polymorphisms (HindIII and PvuII) of the LPL gene have already been shown to correlate significantly with dyslipidemia. We investigated whether these polymorphisms are associated with increased risk of ischemic cerebrovascular disease (CVD).

METHODS

We recruited 177 CVD patients (atherothrombotic infarction, n=71; cardioembolic infarction, n=30; lacunar infarction, n=76) and 177 healthy control subjects. Subjects were genotyped for the Ser447Stop mutation and for HindIII/PvuII restriction fragment length polymorphisms of the LPL gene, and the findings were investigated for associations with the clinical subtypes of CVD and with lipid levels.

RESULTS

The Ser447Stop mutation correlated significantly with CVD (0.107 versus 0.158; P=0.035). For the CG+GG versus CC genotype, the odds ratio between control subjects and CVD patients with atherothrombotic infarction was 0.42 (95% CI, 0.18 to 0.99) (P=0.046). Serum HDL cholesterol and triglyceride levels did not correlate significantly with the Ser447Stop genotype. HindIII polymorphism correlated significantly with CVD (0.234 versus 0.169; P=0.031), but the frequency of PvuII polymorphism was not significantly different between groups.

CONCLUSIONS

Our results suggest that the Ser447Stop mutation of the LPL gene is a novel genetic marker for low risk of atherothrombotic cerebral infarction.

Polymorphism of apoprotein E (APOE), methylenetetrahydrofolate reductase (MTHFR) and paraoxonase (PON1) genes in patients with cerebrovascular disease

Although controversial, data on the genetic polymorphism of apoprotein E (APOE), methylenetetrahydrofolate (MTHFR) and paraoxonase (PON1) genes implicate their role in the development of cerebrovascular disease. The aim of this study was to assess the association of polymorphism of APOE, MTHFR and PON1 genes in 56 stroke and 36 carotid stenosis patients, and in 124 control subjects by PCR-restriction fragment length polymorphism analysis. In the stroke group a significantly different MTHFR genotype distribution (p=0.004, odds ratio for T/T of 17.571), but no significant difference in APOE and PON1 allele and genotype distribution compared to the control was found. The carotid stenosis group exhibited a significantly different APOE allele and genotype distribution (p=0.023, odds ratio APOEepsilon3epsilon4 of 4.24), but no significant difference in the MTHFR and PON1 allele and genotype distribution from the control group. The preliminary results obtained in this study revealed an association of the MTHFR and APOE gene polymorphism with cerebrovascular disease, suggesting a significant risk for stroke in subjects who are homozygous for the T allele and for carotid stenosis in subjects having APOEepsilon3epsilon4 genotype. Additional studies in larger patient groups are needed to confirm these observations.

Apolipoprotein E polymorphism and carotid artery intima-media thickness in a random sample of middle-aged men

Genetic polymorphism of apolipoprotein E (apoE) is an important factor in the development of coronary artery disease but the results concerning apoE genotype and carotid artery atherosclerosis remain controversial. We investigated a random sample of 189 Finnish middle aged men (mean age 54 years, range 50-59) to assess the role of apoE in the process of carotid atherosclerosis. Intima-media thickness (IMT) of the carotid artery wall was measured at three standardised segments (common carotid artery, bifurcation and internal carotid artery) by B-mode ultrasonography. Overall mean IMT value was also calculated. The carriers of E3/2 (n=20) genotype had significantly lower (P<0.01) total cholesterol and LDL cholesterol concentrations than carriers of E3/3 genotype (n=109) or the E4 allele (n=60). ApoE polymorphism was associated with common carotid artery IMT (P=0.034) when adjusted for age and body-mass index (model 1). The carriers of E3/2 had on average 9% (95% CI 0.8-16%, P=0.028) lower common carotid IMT values than the carriers of E3/3. After further adjustment with LDL and HDL cholesterol, systolic blood pressure, lipoprotein (a), apolipoprotein B and pack-years of smoking (model 2) the association was not statistically significant. The overall mean IMT varied significantly with apoE genotype (P=0.03 for model 1 and P=0.07 for model 2), and it was also lowest in the carriers of E3/2 genotype. This suggests that apoE E3/2 genotype is a protective factor in the development of carotid artery atherosclerosis in randomly selected middle-aged men. The favourable effect might be mediated at least partly by the lowering effect of E3/2 genotype on serum cholesterol.

Paraoxonase gene polymorphisms are associated with carotid arterial wall thickness in subjects with familial hypercholesterolemia

Human serum paraoxonase (PON) is a high density lipoprotein (HDL) associated enzyme capable of hydrolyzing lipid peroxides in vitro. PON has recently attracted attention as a protective factor against oxidative modification of LDL and may therefore play an important role in the prevention of the atherosclerotic process. Two frequent mutations at the paraoxonase gene locus (PON1) are the leucine (L allele)-->methionine (M allele) and the glutamine (Q allele)-->arginine (R allele) substitutions at residues 55 and 192, respectively. We have examined the influence of these two polymorphisms on carotid atherosclerosis in familial hypercholesterolemia (FH) patients. The allele frequencies of these two polymorphisms were determined by PCR and restriction fragment analysis, for both the FH population and healthy controls. High resolution B-mode ultrasound was used to assess intima-media wall thickness (IMT) of the carotid artery. No differences were found in allele frequencies between the FH and the control population. In FH patients, the LL, LM and MM genotypes at position 55 occurred in 86 (46.0%), 78 (41.7%) and 23 (12.3%) subjects, respectively, whereas the QQ, QR and RR genotypes at position 192 were found in 90 (48.1%), 79 (42.2%) and 18 (9.6%) individuals. When both polymorphisms were considered separately, no different carotid IMTs were found between the genotype groups. However, our data did show a significant association between the various genotypes of the combined polymorphisms at position 55 and 192 of PON1 and the carotid artery IMT in FH subjects. Subjects with the homozygous wildtype LL/QQ for paraoxonase had the highest mean carotid IMTs when compared to other genotypes, combined. Multiple regression analysis demonstrated age (beta=0.34, P<0.0001), total plasma cholesterol (beta=0.17, P=0. 0109) and the LL/QQ genotype of the PON1 gene (beta=0.22, P=0.0018) to be significant risk factors for carotid atherosclerosis in subjects with FH. The LL/QQ genotype could explain 5.3% of total variance of carotid IMT. In conclusion, this is the first study to report an independent association between the combined PON1 polymorphism genotypes and carotid wall thickness. The homozygous wildtype LL/QQ for PON1 may represent an additional risk factor for carotid atherosclerosis in subjects with FH.

Functional variants in the lipoprotein lipase gene and risk cardiovascular disease

The current report is a quantitative review of the relationship between lipoprotein lipase gene variants and cardiovascular disease based on published population-based studies. Sixteen studies, representing 17,630 individuals, report allelic distribution for lipoprotein lipase gene variants among patients and control individuals. Patient outcomes included clinical cardiovascular disease events, documented coronary disease based on angiography, or intimal media thickening by B-mode ultrasonography. Mantel-Haenszel stratified analysis was used to compute a summary odds ratio and 95% confidence intervals for the association between rare allele in the lipoprotein lipase gene and disease status. Because of potential differing effects associated with different lipoprotein lipase variants, each lipoprotein lipase mutant allele was considered separately. The lipoprotein lipase D9N/-93G to T allele has a summary odds ratio of 2.03 (95% confidence interval 1.30-3.18), indicating a twofold increase in risk of coronary disease for carriers with this allelic variant. The summary odds ratio for the relationship of the rare lipoprotein lipase G188E variant with cardiovascular disease is 5.25 (95% confidence interval 1.54-24.29). The lipoprotein lipase N291S allele is associated with a marginal increase in cardiovascular disease (summary odds ratio 1.25, 95% confidence interval 0.99-1.60, P = 0.07). However, there is stronger evidence for a positive association in certain populations. The summary odds ratio for lipoprotein lipase S447X allele is 0.81 (95% confidence interval 0.65-1.0), which indicates a cardioprotective effect of this lipoprotein lipase gene variant. Thus, lipoprotein lipase gene variants are associated with differential susceptibility to cardiovascular disease.

Carotid intima-media thickness and coronary heart disease risk factors in a low-risk population

OBJECTIVE

Coronary heart disease (CHD) risk factors have been consistently related to an increase in carotid intima-media thickness (IMT) in selected populations. However, few studies were population-based and furthermore little attention has been given to the influence of CHD risk factors on IMT in low-risk populations for CHD.

DESIGN

We examined the association between carotid IMT and CHD risk factors in a large (n = 1013) and representative sample of middle-aged men and women in one of the European populations with the lowest CHD risk.

METHODS

High-resolution B-mode ultrasonography of the common carotid arteries was performed.

RESULTS

Age, smoking (not significant in women), body mass index, waist to hip ratio, systolic (SBP) and diastolic blood pressure, alcohol consumption, total and low-density lipoprotein cholesterol, triglycerides, glycaemia, fibrinogen (not significant in women), haematocrit (not significant in men) and insulin (not significant in women) were positively and significantly associated with mean IMT. High-density lipoprotein (HDL) cholesterol (not significant in women) was negatively and significantly associated with mean IMT. In a subsample of 355 men, IMT was not associated with angiotensin I-converting enzyme gene polymorphism. Multivariate analyses showed, in men, independent associations between mean IMT (0.61+/-0.11 mm) and age, pack-years, SBP, HDL cholesterol, alcohol and the interaction between age and alcohol. In women, only age and SBP were independently associated with mean IMT (0.58+/-0.09 mm).

CONCLUSIONS

We found thinner IMT than those found in high-risk populations, suggesting that an increased IMT might reflect local atherosclerosis. Protective factors such as HDL cholesterol or regular and moderate alcohol consumption are probably important determinants of the early stages of atherosclerosis in these low-risk populations.