Apolipoprotein E and carotid artery atherosclerosis: the Rotterdam study

Apolipoprotein E-ε2 and Resistance to Atherosclerosis in Midlife: The PESA Observational Study

BACKGROUND

APOE is a known genetic contributor to cardiovascular disease, but the differential role APOE alleles play in subclinical atherosclerosis remains unclear.

METHODS

The PESA (Progression of Early Subclinical Atherosclerosis) is an observational cohort study that recruited 4184 middle-aged asymptomatic individuals to be screened for cardiovascular risk and multiterritorial subclinical atherosclerosis. Participants were APOE-genotyped, and omics data were additionally evaluated.

RESULTS

In the PESA study, the frequencies for APOE -ε2, -ε3, and -ε4 alleles were 0.060, 0.844, and 0.096, respectively. This study included a subcohort of 3887 participants (45.8±4.3 years of age; 62% males). As expected, APOE-ε4 carriers were at the highest risk for cardiovascular disease and had significantly greater odds of having subclinical atherosclerosis compared with ε3/ε3 carriers, which was mainly explained by their higher levels of low-density lipoprotein (LDL)-cholesterol. In turn, APOE-ε2 carriers were at the lowest risk for cardiovascular disease and had significantly lower odds of having subclinical atherosclerosis in several vascular territories (carotids: 0.62 [95% CI, 0.47-0.81]; P=0.00043; femorals: 0.60 [0.47-0.78]; P=9.96×10-5; coronaries: 0.53 [0.39-0.74]; P=0.00013; and increased PESA score: 0.58 [0.48-0.71]; P=3.16×10-8). This APOE-ε2 atheroprotective effect was mostly independent of the associated lower LDL-cholesterol levels and other cardiovascular risk factors. The protection conferred by the ε2 allele was greater with age (50-54 years: 0.49 [95% CI, 0.32-0.73]; P=0.00045), and normal (<150 mg/dL) levels of triglycerides (0.54 [0.44-0.66]; P=4.70×10-9 versus 0.90 [0.57-1.43]; P=0.67 if ≥150 mg/dL). Omics analysis revealed an enrichment of several canonical pathways associated with anti-inflammatory mechanisms together with the modulation of erythrocyte homeostasis, coagulation, and complement activation in ε2 carriers that might play a relevant role in the ε2's atheroprotective effect.

CONCLUSIONS

This work sheds light on the role of APOE in cardiovascular disease development with important therapeutic and prevention implications on cardiovascular health, especially in early midlife.

REGISTRATION

URL: https://www.clinicaltrials.gov: NCT01410318.

Extracranial carotid artery atherosclerotic plaque and APOE polymorphisms: a systematic review and meta-analysis

Introduction

Carotid atherosclerotic plaque is an important independent risk factor for stroke. Apolipoprotein E (APOE) influences cholesterol levels and certain isoforms are associated with increased carotid atherosclerosis, though the exact association between APOE and carotid plaque is uncertain. The study aimed to evaluate the association between APOE and carotid plaque.

Methods

A systematic review was performed to retrieve all studies which examined the association between carotid plaque and APOE. This study was conducted in accordance with the PRISMA guidelines. Independent readers extracted the relevant data from each study including the type of imaging assessment, plaque definition, frequency of APOE E4 carrier status and type of genotyping. Meta-analyses with an assessment of study heterogeneity and publication bias were performed. Results were presented in a forest plot and summarized using a random-effects model.

Results

After screening 838 studies, 17 studies were included for systematic review. A meta-analysis of 5 published studies showed a significant association between ε4 homozygosity and carotid plaque [odds ratio (OR), 1.53; 95% CI, 1.16, 2.02; p = .003]. Additionally, there was a significant association between patients possessing at least one ε4 allele, heterozygotes or homozygotes, and carotid plaque (OR, 1.25; 95% CI, 1.03, 1.52; p = .03). Lastly, there was no association between ε4 heterozygosity and carotid plaque (OR, 1.08; 95% CI, 0.93, 1.26; p = .30).

Conclusion

APOE ε4 allele is significantly associated with extracranial carotid atherosclerotic plaque, especially for homozygous individuals.

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.

Cardiorespiratory fitness decreases the odds for subclinical carotid plaques in apolipoprotein e4 homozygotes

Some studies suggest that being an apolipoprotein e4 (APOE e4) carrier increases the risk of atherosclerosis, and others suggest that cardiorespiratory fitness (CRF) could play a key role in atherosclerotic prevention. Our aim was to analyze the association of APOE e4 with carotid atherosclerosis and the association of CRF with atherosclerosis in APOE e4 carriers. A cross-sectional analysis based on a subsample of 90 participants in the Aragon Workers' Health Study was carried out. Ultrasonography was used to assess the presence of plaques in carotid territory; the submaximal Chester Step Test was used to assess CRF; and behavioral, demographic, anthropometric, and clinical data were obtained by trained personnel during annual medical examinations. APOE e4e4 participants were categorized into Low-CRF (VO_2max < 35 mL/kg/min) and High-CRF (VO_2max ≥ 35 mL/kg/min) groups. After adjusting for several confounders, compared with APOE e3e3, those participants genotyped as APOE e3e4 and APOE e4e4 showed an OR = 1.60 (95% CI 0.45, 5.71) and OR = 4.29 (95% CI 1.16, 15.91), respectively, for carotid atherosclerosis. Compared to Low-CRF APOE e4e4 carriers, the odds of carotid plaque detection were 0.09 (95% CI 0.008, 0.98) times lower among High-CRF APOE e4e4 carriers. The APOE e4e4 genotype was associated with increased carotid atherosclerosis. However, CRF is a modifiable factor that may be targeted by APOE e4e4 to decrease the elevation of atherosclerotic risk due to this genetic condition.

Effect of Apolipoprotein E ε4 Allele on the Progression of Carotid Atherosclerosis Through Apolipoprotein Levels

Background

Patients and methods

Results

Conclusion

Effects of Apolipoprotein E polymorphism on carotid intima-media thickness, incident myocardial infarction and incident stroke

The Apolipoprotein E (APOE) gene polymorphism (rs429358 and rs7412) shows a well-established association with lipid profiles, but its effect on cardiovascular disease is still conflicting. Therefore, we examined the association of different APOE alleles with common carotid artery intima-media thickness (CCA-IMT), carotid plaques, incident myocardial infarction (MI) and stroke. We analyzed data from 3327 participants aged 20-79 years of the population-based Study of Health in Pomerania (SHIP) from Northeast Germany with a median follow-up time of 14.5 years. Linear, logistic, and Cox-regression models were used to assess the associations of the APOE polymorphism with CCA-IMT, carotid plaques, incident MI and stroke, respectively. In our study, the APOE E2 allele was associated with lower CCA-IMT at baseline compared to E3 homozygotes (β: - 0.02 [95% CI - 0.04, - 0.004]). Over the follow-up, 244 MI events and 218 stroke events were observed. APOE E2 and E4 allele were not associated with incident MI (E2 HR: 1.06 [95% CI 0.68, 1.66]; E4 HR: 1.03 [95% CI 0.73, 1.45]) and incident stroke (E2 HR: 0.79 [95% CI 0.48, 1.30]; E4 HR: 0.96 [95% CI 0.66, 1.38]) in any of the models adjusting for potential confounders. However, the positive association between CCA-IMT and incident MI was more pronounced in E2 carriers than E3 homozygotes. Thus, our study suggests that while APOE E2 allele may predispose individuals to lower CCA-IMT, E2 carriers may be more prone to MI than E3 homozygotes as the CCA-IMT increases. APOE E4 allele had no effect on CCA-IMT, plaques, MI or stroke.

Relationship of Apolipoproteins with Subclinical Cardiovascular Risk in Youth

OBJECTIVE

To examine the association of apolipoproteins with arterial stiffness and carotid artery structure in children and adolescents.

STUDY DESIGN

A total of 338 children and adolescents (178 female) with a mean age 13.0 ± 2.8 years were examined. Apolipoproteins (AI, AII, B₁₀₀, CII, CIII, and E) were measured via human apolipoprotein magnetic bead panel. Applanation tonometry determined pulse wave velocity and ultrasound imaging measured carotid intima-media thickness. Dual X-ray absorptiometry measured total body fat percent. Linear regression models were adjusted for Tanner stage, sex, and race with further adjustments for body fat percent. Linear regression models also examined the interaction between Tanner stage and apolipoproteins.

RESULTS

There was a significant positive association between pulse wave velocity and apolipoproteins: AI (0.015 m/s/10 μg/mL [CI 0.005-0.026], P = .003), AII (0.036 m/s/10 μg/mL [0.017-0.056], P < .001), B₁₀₀ (0.009 m/s/10 μg/mL [0.002-0.016], P = .012), E (0.158 m/s/10 μg/mL [0.080-0.235], P < .001), and CIII:CII (0.033/μg/mL [0.014-0.052], P < .001). After we added body fat percent to the models, pulse wave velocity (PWV) remained positively associated with greater levels of apolipoproteins: AI, AII, B₁₀₀, E, and CIII:CII. Both with and without the adjustment for body fat percent, there were no significant associations between any apolipoprotein and carotid intima-media thickness. There were no significant interactions between Tanner stage and apolipoproteins.

CONCLUSIONS

These findings suggest that greater levels of apolipoprotein AII, E, and CIII:CII are associated with increased arterial stiffness in children and adolescents, both with and without adjusting for percent body fat. These specific apolipoproteins may be useful as biomarkers of cardiovascular risk.

Genetic susceptibility to cerebrovascular disease: A systematic review

Investigation of genetic susceptibility to cerebrovascular disease has been of growing interest. A systematic review of human studies assessing neurogenomic aspects of cerebrovascular disease was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. Any association study exploring genetic variants located in the exome associated with one of the major cerebrovascular diseases with at least 500 subjects was eligible for inclusion. Of 6874 manuscripts identified, 35 studies met the inclusion criteria. Most studies of interest focused on ischemic stroke and cerebrovascular occlusive disease. Large cohort genetic association studies on hemorrhagic cerebrovascular disease were less common. In addition to rare, well-established monogenic conditions with significant risk for cerebrovascular disease, a number of genetic variants are also relevant to cerebrovascular pathogenesis as part of a multifactorial process. The 45 polymorphisms identified were located in genes involved in processes related to endothelial and vascular health (15 (33.4%) variants), plasma lipid metabolism (10 (22.2%) variants), inflammation (9 (20%) variants), coagulation (3 (6.7%) variants), and blood pressure modulation (2 (4.4%) variants), and other (6 (13.3%) variants). This work represents a comprehensive overview of genetic variants in the exome relevant to ischemic and hemorrhagic stroke pathophysiology.

Endothelial nitric oxide synthase Glu 298 Asp (G894T) and Apolipoprotein E gene polymorphism as possible risk factors for coronary heart disease among Egyptians

In Egypt, The prevalence of chronic heart disease (CHD) is 8.3%. It is the principal cause of death and is responsible for 22% of total mortality. The age-adjusted mortality rate is 174 per 100,000 of population. There are many studies on traditional risk factors and CHD in Egypt but the study of novel risk factors is deficient.

Objectives

The aim of the present case control study was to investigate the relation between CHD susceptibility and Endothelial Nitric Oxide Synthase (eNOS) Glu 298 Asp (G894T) and Apolipoprotein E (ApoE) gene polymorphism in a cohort of Egyptian individuals.

Methods

Genotyping of eNOS (Glu298Asp) and Apo E genes polymorphisms were done using polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) method for 100 CHD cases and 100 age and sex matched healthy controls.

Results

A statistically significant association was observed between GT and TT genotypes of endothelial nitric oxide synthase gene with CHD with OR = 2.03 and 3.5; respectively. Also, carriers of E4 allele and especially E3/E4 genotype were at higher risk of CHD with OR = 3.3 for both. Significant association was also observed between the presence of combined GTE3E4 genotype and CHD with OR = 6.6.

Conclusion

GT and TT genotypes of endothelial nitric oxide synthase gene, E3/E4 genotype of Apo E gene polymorphism and combined GTE3E4 genotype can be considered risk factors for the development of CHD among Egyptians.

Apolipoprotein E Gene Polymorphism and Subclinical Carotid Atherosclerosis: The Northern Manhattan Study

BACKGROUND

Apolipoprotein E (APOE) polymorphism has previously been associated with carotid intima-media thickness (cIMT) in predominantly Caucasian populations. We sought to test the strength of the relationship between APOE-ε4 carrier status and subclinical atherosclerosis in a tri-ethnic population with a large Hispanic representation.

METHODS

We assessed the association between APOE polymorphism and cIMT and plaque burden among 1243 stroke-free individuals (mean age 69 years, 65% Hispanic, 18% black, 17% white) using a sequence of multivariable regression models.

RESULTS

After adjusting for demographics, vascular risk factors and plasma low-density lipoprotein (LDL) levels, APOE-ε4 carrier status was positively associated with cIMT (mean difference, .013 mm; 95% confidence interval, .003-.023 mm). The APOE-ε4 association with cIMT appeared to be segment-specific with greater differences in IMT between APOE-ε4 carriers and noncarriers in the common carotid artery (CCA, .014 mm) and bifurcation (.017 mm) than in the internal carotid artery (ICA) IMT (.007 mm). This relationship was not modified by race-ethnicity. Presence of diabetes modified the ε4-cIMT relationship in CCA (P = .045) and ICA (P = .046). APOE-ε4 carrier status was not associated with plaque presence or plaque area.

CONCLUSIONS

APOE-ε4 carriers had elevated cIMT independent of demographics and vascular risk factors including LDL levels. Diabetes was an effect modifier of the relationship between APOE-ε4 and IMT, such that ε4 carriers with diabetes had greater IMT in the CCA and ICA than those without diabetes. The APOE-IMT relationship was not modified by race-ethnicity.

Review: Lipids and stroke

Stroke is the third leading cause of death in adults. Although vascular disease is the prime contributor to its pathogenesis, dyslipidaemia is not unambiguously established as a risk factor for stroke in the same way that it is for coronary artery disease. Non-statin treatments of dyslipidaemia have not been shown clearly to help in preventing stroke. However, large clinical trials of treatment with statins over a number of years have demonstrated that these drugs decrease ischaemic stroke rates in persons at risk. Whether this reflects the efficacy of statins in lowering low density lipoprotein-cholesterol (LDL-c) concentrations alone or whether additional mechanisms may apply is not clear.

Apolipoprotein E and First-ever Ischaemic Stroke in Greek Hospitalized Patients

The association between apolipoprotein E (ApoE) polymorphism and stroke is still controversial. This study investigated the potential association between ApoE genotypes and stroke subtypes, and risk factors for ischaemic stroke in Greek patients hospitalized with their first-ever ischaemic stroke. One hundred patients (70 men and 30 women; mean age ± SD 60.7 ± 9.8 years) were included in the study. The control group comprised 96 age-and sex-matched healthy volunteers. Cerebral infarction was classified as atherothrombotic, cardio-embolic or lacunar small-vessel stroke. The three common ApoE alleles (E2, E3 and E4) were determined using the seminested polymerase chain reaction. No significant difference in the ApoE alleles was found between patients and controls. Similarly, there was no significant association between ApoE alleles and stroke subtypes, common risk factors for ischaemic stroke and neck vessel stenosis. Although the sample size was small, these results do not support a role for ApoE polymorphism in the pathogenesis of ischaemic stroke.

APOE ϵ 2 allele is an independent risk factor for vulnerable carotid plaque in ischemic stroke patients

BACKGROUND AND AIMS

The data about apolipoprotein E gene (APOE) genotype and the risk of stroke are inconsistent. The APOE genotype is expected to influence the development of carotid plaques. Our aim was to look for association between APOE genotype and carotid plaque morphology in ischemic stroke patients.

METHODS AND RESULTS

Data of ischemic stroke patients was collected prospectively for 2 years. The degree of stenosis and plaque echogenicity and surface were assessed with ultrasound. Subsequent APOE genotypes were compared: APOE ϵ 3/ϵ 3 (E3--reference), APOE ϵ 2/ϵ 3 (E2 group) and APOE ϵ 3/ϵ 4, APOE ϵ 4/ϵ 4 (E4 group). We included 388 patients with acute ischemic stroke. Patients in E2 group had more often hypoechogenic, ulcerated plaques and severe stenosis comparing to E3 patients. On logistic regression analysis, ϵ 2 genotype remained an independent risk factor for vulnerable carotid plaque (OR  =  2.3 for <60% stenosis and OR  =  2.7 for ≥60% stenosis; 95% CI).

CONCLUSIONS

This study suggests that ϵ 2 allele is an independent risk factor for echolucent and ulcerated carotid plaque.

Apolipoprotein E genotype, cardiovascular biomarkers and risk of stroke: systematic review and meta-analysis of 14,015 stroke cases and pooled analysis of primary biomarker data from up to 60,883 individuals

BACKGROUND

At the APOE gene, encoding apolipoprotein E, genotypes of the ε2/ε3/ε4 alleles associated with higher LDL-cholesterol (LDL-C) levels are also associated with higher coronary risk. However, the association of APOE genotype with other cardiovascular biomarkers and risk of ischaemic stroke is less clear. We evaluated the association of APOE genotype with risk of ischaemic stroke and assessed whether the observed effect was consistent with the effects of APOE genotype on LDL-C or other lipids and biomarkers of cardiovascular risk.

METHODS

We conducted a systematic review of published and unpublished studies reporting on APOE genotype and ischaemic stroke. We pooled 41 studies (with a total of 9027 cases and 61,730 controls) using a Bayesian meta-analysis to calculate the odds ratios (ORs) for ischaemic stroke with APOE genotype. To better evaluate potential mechanisms for any observed effect, we also conducted a pooled analysis of primary data using 16 studies (up to 60,883 individuals) of European ancestry. We evaluated the association of APOE genotype with lipids, other circulating biomarkers of cardiovascular risk and carotid intima-media thickness (C-IMT).

RESULTS

The ORs for association of APOE genotypes with ischaemic stroke were: 1.09 (95% credible intervals (CrI): 0.84-1.43) for ε2/ε2; 0.85 (95% CrI: 0.78-0.92) for ε2/ε3; 1.05 (95% CrI: 0.89-1.24) for ε2/ε4; 1.05 (95% CrI: 0.99-1.12) for ε3/ε4; and 1.12 (95% CrI: 0.94-1.33) for ε4/ε4 using the ε3/ε3 genotype as the reference group. A regression analysis that investigated the effect of LDL-C (using APOE as the instrument) on ischaemic stroke showed a positive dose-response association with an OR of 1.33 (95% CrI: 1.17, 1.52) per 1 mmol/l increase in LDL-C. In the separate pooled analysis, APOE genotype was linearly and positively associated with levels of LDL-C (P-trend: 2 × 10(-152)), apolipoprotein B (P-trend: 8.7 × 10(-06)) and C-IMT (P-trend: 0.001), and negatively and linearly associated with apolipoprotein E (P-trend: 6 × 10(-26)) and HDL-C (P-trend: 1.6 × 10(-12)). Associations with lipoprotein(a), C-reactive protein and triglycerides were non-linear.

CONCLUSIONS

In people of European ancestry, APOE genotype showed a positive dose-response association with LDL-C, C-IMT and ischaemic stroke. However, the association of APOE ε2/ε2 genotype with ischaemic stroke requires further investigation. This cross-domain concordance supports a causal role of LDL-C on ischaemic stroke.

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.

Associations between APOE genotypes and disease susceptibility, joint damage and lipid levels in patients with rheumatoid arthritis

OBJECTIVE

Apolipoprotein E (APOE) genotypes are associated with cardiovascular disease (CVD) and lipid levels. In rheumatoid arthritis (RA), an association has been found with disease activity. We examined the associations between APOE genotypes and disease susceptibility and markers of disease severity in RA, including radiographic joint damage, inflammatory markers, lipid levels and cardiovascular markers.

METHOD

A Norwegian cohort of 945 RA patients and 988 controls were genotyped for two APOE polymorphisms. We examined longitudinal associations between APOE genotypes and C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) as well as hand radiographs (van der Heijde Sharp Score(SHS)) in 207 patients with 10 year longitudinal data. Lipid levels, cardiovascular markers and history of CVD were compared across genotypes in a cross sectional study of 136 patients. Longitudinal radiological data of cohorts from Lund and Leiden were available for replication. (N = 935, with 4799 radiographs).

RESULTS

In the Norwegian cohort, associations between APOE genotypes and total cholesterol (TC) and low-density lipoproteins (LDL) were observed (ε2 < ε3/ε3 < ε4, p = 0.03 and p = 0.02, respectively). No association was present for acute phase reactant or CVD markers, but a longitudinal linear association between APOE genotypes and radiographic joint damage was observed (p = 0.007). No association between APOE genotypes and the severity of joint destruction was observed in the Lund and Leiden cohorts, and a meta- analysis combining all data was negative.

CONCLUSION

APOE genotypes are associated with lipid levels in patients with RA, and may contribute to dyslipidemia in some patients. APOE genotypes are not consistently associated with markers of inflammation or joint destruction in RA.

Association between apolipoprotein E polymorphism and subclinic atherosclerosis in patients with type 1 diabetes mellitus

OBJECTIVE

The most important cause of morbidity and mortality in type 1 diabetes mellitus (DM) is atherosclerosis. Apolipoprotein E (Apo E) polymorphism is accused of being the genetic risk factor for atherosclerosis. The aim of the present study was to determine which Apo E polymorphism was related to atherosclerosis in patients with type 1 DM.

METHODS

Seventy-four patients with type 1 DM were enrolled in the study. Age, diabetes duration, daily insulin dose, microalbuminuria, and major cardiovascular risk factors including anthropometric and metabolic parameters were assessed in each patient. Non-invasive ultrasonographic measurements were also performed. For determination of Apo E genotype, DNA was extracted from venous blood from all subjects using standard methods. Apo E genotyping was performed using a PCR-restriction fragment-length polymorphism assay.

RESULTS

Systolic blood pressure and carotid artery intima-media thickness (CA-IMT) were increased in subjects with E4/E4 polymorphism. According to univariate analysis, when adjusted for all risk factors, genotypes did not differ for total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglycerides (p>0.05). However, E3/E3, E3/E4 and E4/E4 genotypes were found to be associated with an increase in CA-IMT (p<0.001).

CONCLUSIONS

Our results suggest that the polymorphism associated with atherosclerosis in type1 DM is Apo E4/E4.

The association of APOE genotype with cognitive function in persons aged 35 years or older

APOE genotype is associated with the risk of Alzheimer's disease. In the present study, we investigated whether APOE genotype was associated with cognitive function in predominantly middle-aged persons. In a population-based cohort of 4,135 persons aged 35 to 82 years (mean age (SD), 55 (12) years), cognitive function was measured with the Ruff Figural Fluency Test (RFFT; worst score, 0 points; best score, 175 points). APOE genotype (rs429358 and rs7412) was determined by polymerase chain reaction. The mean RFFT score (SD) of the total cohort was 69 (26) points. Unadjusted, the mean RFFT score in homozygous APOE ε4 carriers was 4.66 points lower than in noncarriers (95% confidence interval, -9.84 to 0.51; p = 0.08). After adjustment for age and other risk factors, the mean RFFT score in homozygous APOE ε4 carriers was 5.24 points lower than in noncarriers (95% confidence interval, -9.41 to -1.07; p = 0.01). The difference in RFFT score was not dependent on age. There was no difference in RFFT score between heterozygous APOE ε4 carriers and noncarriers. The results indicated that homozygous APOE ε4 carriers aged 35 years or older had worse cognitive function than heterozygous carriers and noncarriers.

Relationship between ApoE gene polymorphism and coronary heart disease in Gaza Strip

BACKGROUND

Apolipoprotein E (ApoE) plays a role in the regulation of lipid metabolism in humans. ApoE, a 229-amino-acid polypeptide, is classified into three major isoforms (E2, E3, and E4) according to the differences in amino acids at positions 112 and 158. In the normal population, ApoE3 isoform is the most prevalent, and ApoE2 or E4 is frequently associated with hyperlipoproteinemia. The objective of this work was to investigate the relationship between ApoE gene polymorphism and coronary heart disease (CHD) in Gaza Strip and investigate the association between serum lipid levels and CHD.

MATERIAL AND METHODS

The study population consisted of 137 subjects including 69 CHD cases (45 male, 24 female) and 68 healthy subjects (33 male and 35 female).

RESULTS

The ApoE3/E3 genotype was the most common in the control and the CHD groups. ApoE2/E3 and ApoE3/E4 were the next most common genotypes. The frequencies of ApoE alleles in the CHD subjects were 0.826 for E3, 0.137 for E4, and 0.0362 for E2. These frequencies are comparable to those found in the control group which were 0.875 for the E3, 0.073 for E4, and 0.0515 for E2. No statistically significant differences in ApoE genotypes were found between the patients and the control groups. Moreover, there was no significant difference between the mean of triglyceride (TG) and HDL levels among different ApoE genotypes. However, there was a significant difference in the mean of LDL and ApoE genotypes where the mean of LDL was 218.17 mg/dl in ApoE4, 149.67 mg/dl in ApoE2, and 184.52 mg/dl in ApoE3. A significant difference was also evident between the mean of LDL levels in the CHD and the control group where the mean of LDL was 126 mg/dl in CHD and 111.47 mg/dl in the control group. Our study indicated that there was no significant difference between the mean of cholesterol and TG levels of the CHD and the control groups.

CONCLUSIONS

To our knowledge, this is the first study in Gaza Strip investigating the relation between ApoE genotypes and CHD. Further investigations are needed to link other genetic factors to CHD.

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.

Genetic-epidemiological evidence on genes associated with HDL cholesterol levels: a systematic in-depth review

High-density lipoprotein (HDL) particles exhibit multiple antiatherogenic effects. They are key players in the reverse cholesterol transport which shuttles cholesterol from peripheral cells (e.g. macrophages) to the liver or other tissues. This complex process is thought to represent the basis for the antiatherogenic properties of HDL particles. The amount of cholesterol transported in HDL particles is measured as HDL cholesterol (HDLC) and is inversely correlated with the risk for coronary artery disease: an increase of 1mg/dL of HDLC levels is associated with a 2% and 3% decrease of the risk for coronary artery disease in men and women, respectively. Genetically determined conditions with high HDLC levels (e.g. familial hyperalphalipoproteinemia) often coexist with longevity, and higher HDLC levels were found among healthy elderly individuals. HDLC levels are under considerable genetic control with heritability estimates of up to 80%. The identification and characterization of genetic variants associated with HDLC concentrations can provide new insights into the background of longevity. This review provides an extended overview on the current genetic-epidemiological evidence from association studies on genes involved in HDLC metabolism. It provides a path through the jungle of association studies which are sometimes confusing due to the varying and sometimes erroneous names of genetic variants, positions and directions of associations. Furthermore, it reviews the recent findings from genome-wide association studies which have identified new genes influencing HDLC levels. The yet identified genes together explain only a small amount of less than 10% of the HDLC variance, which leaves an enormous room for further yet to be identified genetic variants. This might be accomplished by large population-based genome-wide meta-analyses and by deep-sequencing approaches on the identified genes. The resulting findings will probably result in a re-drawing and extension of the involved metabolic pathways of HDLC metabolism.

Apolipoprotein E polymorphism is associated with both carotid and coronary atherosclerosis in patients with coronary artery disease

BACKGROUND AND AIMS

Apolipoprotein E (apoE) polymorphism plays a significant role in the development of atherosclerosis and cardiovascular disease. Therefore, the aim of the present study was to examine the association between apoE polymorphism and carotid intima-media thickness (IMT), and severity and extent of coronary artery disease (CAD).

METHODS AND RESULTS

B-mode ultrasound and quantitative coronary angiography (QCA) were used to assess carotid, and coronary artery atherosclerosis in 91 patients with clinically suspected CAD referred for cardiac catheterization. Two apoE phenotype groups were defined: apoE3 (E3/E3) and apoE4 (including E4/E3, E4/E4 phenotypes). Maximum IMT was higher in the apoE4 group than in the apoE3 group (p=0.022). The global atheroma burden index was similarly higher in the apoE4 group than in the apoE3 group (p=0.033). ApoE4 subjects had higher levels of apolipoprotein B (apoB) (p=0.008), triglycerides (p=0.006), remnant lipoprotein-cholesterol (RLP-C) (p=0.023), and lipoprotein(a) [(Lp(a)] (p=0.041) than apoE3 subjects. The mean LDL particle size was smaller in the apoE4 group than in the apoE3 group (p=0.041).

CONCLUSIONS

ApoE polymorphism was associated with both carotid and coronary atherosclerosis. Patients with the apoE4 isoform had an increased carotid IMT and a more severe and extensive CAD than patients with the apoE3 isoform.

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.

What is the relationship among atherosclerosis markers, apolipoprotein E polymorphism and dementia?

Evidence suggests the important role of vascular factors both in vascular dementia (VaD) and Alzheimer disease (AD) pathogenesis. However, the relationship between apolipoprotein E (APOE) polymorphism and markers of atherosclerosis is still controversial. The aim of the study was to investigate the interplay between APOE polymorphisms and atherosclerosis in patients with AD and VaD. In this cross-sectional study, 101 demented (68 AD and 33 VaD) patients underwent APOE genotyping and neck vessel ultrasound to evaluate carotid artery disease [intima-media thickness (IMT) and plaques]. Patients with AD carrying epsilon4 allele presented increased IMT values with respect to non-epsilon4 carriers and VaD patients, whereas no relation was found between APOE polymorphisms and the presence or grade of carotid plaques both in AD and VaD patients. The epsilon4 APOE allele may promote intima-media thickening, interacting with other factors contributing to AD development.

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.

Protective effect of apolipoprotein E2 on coronary artery disease in African Americans is mediated through lipoprotein cholesterol

We studied the relationship of apolipoprotein E (apoE) isoforms and coronary artery disease (CAD) in 224 African Americans and 326 Caucasians undergoing diagnostic coronary angiography. The presence of CAD was defined as >50% stenosis in at least one artery. ApoE allele frequencies were 0.12, 0.62, and 0.26 for epsilon 2, epsilon 3, and epsilon 4, respectively, in African Americans and 0.08, 0.78, and 0.14 for epsilon 2, epsilon 3, and epsilon 4, respectively, in Caucasians. Among African Americans, CAD was present in 9 of 34 epsilon 2 carriers (26%), significantly smaller (P < 0.05) in proportion compared with 39 of 82 epsilon 3 carriers and 43 of 92 epsilon 4 carriers (48% and 47%, respectively), suggesting a protective effect of the epsilon 2 allele. No such difference was seen in Caucasians. In African Americans but not Caucasians, LDL cholesterol was lower in epsilon 2 carriers than in epsilon 3 and epsilon 4 carriers (106 vs. 127 and 134 mg/dl, respectively; P < 0.005). After adjusting for lipid levels, the association between apoE2 and CAD was no longer significant. Thus, the protective effect of apoE2 seen in African Americans could be explained by a favorable lipid profile in epsilon 2 carriers, whereas in Caucasians, the absence of such a protective effect could be attributable to the lack of effect of apoE2 on the lipid profile.

Apolipoprotein E polymorphisms predict low density lipoprotein cholesterol levels and carotid artery wall thickness but not incident coronary heart disease in 12,491 ARIC study participants

Elevated levels of low density lipoprotein (LDL) cholesterol is a well-established risk factor for cardiovascular disease, and recent advancements have provided evidence that carotid artery intima-media thickness (IMT) is associated with increased occurrence of cardiovascular events. Apolipoprotein E (ApoE) has been widely studied in regard to its role in lipid transport and metabolism, but the role that ApoE genetic variation plays in relation to carotid artery IMT and risk of incident coronary heart disease remains a subject of debate. In 1987-2001, the authors examined the effect of each ApoE allele (epsilon2, epsilon3, epsilon4) on LDL cholesterol and carotid IMT, as well as the association with coronary heart disease risk, in 12,491 participants of the US Atherosclerosis Risk in Communities Study. ApoE epsilon2, epsilon3, and epsilon4 allele frequencies were determined, respectively, in Whites (0.08, 0.77, 0.15) and African Americans (0.11, 0.67, 0.22). These alleles did not predict incident coronary heart disease in either racial group. The ApoE epsilon2 allele was associated with lower LDL cholesterol and the epsilon4 allele with higher LDL cholesterol in both Whites and African Americans. The ApoE epsilon2 and epsilon4 alleles were associated with carotid IMT measures in both racial groups, but, after adjusting for lipid parameters, only the epsilon4 allele was associated with carotid IMT measures in African Americans.

Apolipoprotein E Polymorphism and Stroke Subtypes in an Italian Cohort

BACKGROUND

Studies have indicated that apolipoprotein E (ApoE)-epsilon4 is a risk factor for ischemic cerebrovascular diseases (ICVD), but the existence of this association is still controversial. The aims of this study were: (1) to compare ApoE genotype and allele frequencies in Italian cases with ICVD and in healthy control subjects and (2) to compare ApoE allele frequencies among ischemic stroke subtypes.

METHODS

A hospital-based cohort of 302 Italian subjects with ICVD and 228 healthy subjects have been recruited to investigate the role of ApoE polymorphisms as risk factors for ICVD. TOAST criteria were employed to stratify ICVD cases by subtypes.

RESULTS

No significant differences in ApoE genotype and allele frequencies were found between cases and control subjects. The frequency of ApoE-epsilon4 was lower in cases than in control subjects (6% vs. 10.1%), although not significantly. No differences in ApoE genotype and allele frequencies were evident among ICVD subtypes. However, out of 36 ApoE-epsilon4 alleles 23 (3.7%) were found in subjects with ICVD related to primary degenerative arterial disease related to large vessel disease and small vessel disease, and 13 (2.1%) in remaining subjects. Using logistic regression analysis we assessed whether ApoE-epsilon4 allele was independently associated with risk of ICVD related to a primary degenerative arterial disease compared to other ICVD subtypes. While classical risk factors were significantly associated with higher risk for ICVD due to large vessel disease and small vessel disease than other ICVD subtypes, the role of ApoE-epsilon4 allele was not significant (OR 1.25, 95% CI 0.57-2.74).

CONCLUSION

Our study shows similar ApoE-epsilon4 genotype and allele frequencies in patients with ICVD and in control subjects. No differences were found among different ICVD subtypes either.

POLYMORPHISMS OF APOLIPOPROTEIN E AND ANGIOTENSIN-CONVERTING ENZYME GENES AND CAROTID ATHEROSCLEROSIS IN HEAVY DRINKERS

AIMS

To investigate the influence of apolipoprotein E (APOE) and angiotensin-converting enzyme (ACE) gene polymorphisms on carotid artery atherosclerosis in alcoholism.

METHODS

Polymorphism of both genes was identified by DNA analysis in 130 male alcohol-dependent patients. Intima-media thickness (IMT) was measured ultrasonographically.

RESULTS

Multivariate regression analysis showed that of all the known risk factors the greatest impact on carotid atherosclerosis in alcoholics was exerted by age, hypertension, LDL cholesterol and fasting plasma glucose levels. Subjects carrying the APO E epsilon4 allele were more liable to develop atherosclerotic changes in carotid arteries compared with subjects with the epsilon3/3 genotype, which showed statistical significance in patients under 50 years of age. No association was shown between ACE I/D polymorphism and carotid atherosclerosis.

CONCLUSIONS

APO E polymorphism can increase the risk of carotid atherosclerosis development in an alcoholic subject. The association of the APO E epsilon4 allele with carotid atherosclerosis was significant in younger patients. Since the elevated carotid IMT is considered to be a good marker of increased risk of generalized atherosclerosis the consequences could involve both cardiac and cerebrovascular events.

The concomitant presence of polymorphic alleles of interleukin-1beta, interleukin-6 and apolipoprotein E is associated with an increased risk of myocardial infarction in elderly men. Results from a pilot study

Genetic background of inflammatory or anti-inflammatory molecules may be helpful in identifying subjects with increased or decrease risk of developing cardiovascular disease. Bi-allele polymorphism (C > T) in the promoter region (-511) of the interleukin-1beta (IL-1beta) gene and the bi-allele polymorphism (G > C) in the promoter region (-174) of interleukin-6 (IL-6) gene were determined in elderly men patients with myocardial infarction (MI) and healthy controls. Each subject was also genotyped for the triallelic polymorphism of the apolipoprotein E epsilon gene. The IL-6C and APOE epsilon4 alleles were independently associated with a mild or moderate increased risk of MI, whilst the allele C of the IL-1beta was not independently linked to MI risk. However, the simultaneous presence of the allele C of IL-1beta, the allele C of IL-6 and epsilon4 allele of APOE was strongly associated with the disease. Data from this cross-sectional study suggest that the functional interaction of these three genes affects pathogenetic mechanisms of MI and an impaired regulation of immune responses plays a pivotal role in the disease. Furthermore, genetic background of inflammatory genes may influence longevity of human species by affecting inflammatory responses associated to cardiovascular diseases. The administration of anti-inflammatory compounds to middle age healthy subjects with increased genetic susceptibility of developing MI might decrease the incidence and prevalence of cardiovascular events in aging.

The increase in cholesterol with menopause is associated with the apolipoprotein E genotype. A population-based longitudinal study

During menopause, a sharp increase in cholesterol concentration occurs with an unexplained wide variation in change. Possibly, this is attributable to genetic variation. The authors prospectively studied the effect of the apolipoprotein E (APOE) genotype on the change in cholesterol level with menopause among 1116 Dutch women. Women with the APOE3E3 genotype were regarded as the reference category and changes were adjusted for age at baseline, years of follow-up, years since menopause, and body mass index. At baseline, the women were on average 50.4 years. After 5.9 years of follow-up, the women were on average 4.3 years (S.D. 1.5 years) postmenopausal. The mean increase in cholesterol with menopause in women with the APOE3E3 genotype was 0.67 mmol/L (95% CI, 0.61-0.72 mmol/L). In women with the APOE2E3 genotype the increase in cholesterol was 0.44 mmol/L (CI, 0.32-0.56 mmol/L). The increase in cholesterol in women with the APOE3E4 genotype did not differ from the increase in women with the APOE3E3 genotype. These results show that the increase in cholesterol level with menopause is 30% lower in women with the APOE2E3 genotype when compared with women with the APOE3E3 genotype, indicating that the APOE genotype contributes to the variation in cholesterol increase with menopause.

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.

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.

Apolipoprotein E epsilon4 allele is associated with left ventricular systolic dysfunction

BACKGROUND

Apolipoprotein (APOE) epsilon4 allele has been associated with cardiac dysfunction in Alzheimer's disease and beta-thalassemia. We investigated the association between APOE genotypes and left ventricular dysfunction in a population of community-dwelling elderly subjects.

METHODS

This study was performed in the Rotterdam Study, a population-based prospective cohort study among elderly subjects. For 2206 participants, a baseline echocardiogram and blood specimens for APOE typing were available. Cardiac dysfunction was considered present when fractional shortening was <or=25%. Multivariate logistic regression was used to calculate odds ratios (ORs). The epsilon3/epsilon3 genotype served as a reference category.

RESULTS

In participants who were homozygous for the epsilon4 allele, the odds of cardiac dysfunction was increased 3-fold (OR, 3.1; 95% CI, 1.2-8.1), whereas the odds of cardiac dysfunction in persons with APOE epsilon3/epsilon4 was not significantly increased (OR, 1.5; 95% CI, 0.9-2.5). There was a significant allele-effect relationship for the epsilon4 allele (P-trend <.05). These elevated odds remained after adjustment for cholesterol levels and atherosclerosis parameters. Risks associated with APOE epsilon4/epsilon4 and APOE epsilon3/epsilon4 were more pronounced in participants aged >or=65 years.

CONCLUSION

The APOE epsilon4 allele is an independent risk factor for cardiac dysfunction in elderly people. Besides well-known effects on atherosclerosis and cholesterol levels, there may be other mechanisms, such as apoptosis, through which this allele exerts negative effects on myocardial performance.

Genetics of intima-media thickness

PURPOSE OF REVIEW

Increased carotid artery intima-media thickness is associated with an increased risk of coronary heart disease or cerebrovascular disease and is a powerful predictor of cardiovascular and cerebrovascular outcomes. Consequently, the measurement is now used in a number of case control, cohort and familial and linkage studies as an intermediate phenotype for the investigation of the genetic and environmental determinants of atherosclerosis. The aim of this paper is to review the most recent available data on the genetic determinants of carotid intima-media thickness.

RECENT FINDINGS

Genes could account for a significant amount of variation in carotid intima-media thickness: up to 30-66%. Carotid intima-media thickness progressed more rapidly with age in familial hypercholesterolemia patients than in patients without his condition. Familial hypercholesterolemia patients with a null LDL receptor allele tended to have higher carotid intima-media thickness than patients carrying the LDL receptor defective allele. Small association studies showing positive or negative results with the angiotensinogen gene variants as well as with the angiotensin converting enzyme I/D polymorphism add to the confusion in this largely controversial area. Differing results may depend on the vascular territory and genetic background. New associations have been described in small studies.

SUMMARY

Studies on the association of polymorphisms and intima-media thickness are frequently disappointing and lead occasionally to conflicting results. Among study limitations is the fact that mostly single gene effects are considered; longitudinal cohort studies may be more appropriate than case control studies. Ongoing large prospective population studies and clinical trials have integrated the measurements of intima-media thickness and genotype determination with a genomic approach. As a result, in the near future we may see more important and robust results with significant consequences on our understanding of genetic determinants of atherosclerotic cardiovascular disease.

Effect of polymorphism of the endothelial nitric oxide synthase and apolipoprotein E genes on carotid atherosclerosis in hemodialysis patients

BACKGROUND

Decreased synthesis of nitric oxide (NO) and dyslipidemia are implicated in the development of atherosclerosis.

METHODS

We investigated the relationship between endothelial NO synthase (eNOS) gene polymorphism, apolipoprotein E (apoE) polymorphism, and carotid atherosclerosis in 163 hemodialysis patients with nondiabetic nephropathy. Intima media thickness of the carotid artery was measured by ultrasonography, and subjects were classified according to the presence or absence of carotid plaque. Multivariate odds ratios were calculated to assess the combined influence of several variables on the existence of carotid plaque, with clinical factors, the intron 4 polymorphism, T(-786)-->C polymorphism, and Glu298Asp polymorphism of eNOS and the apoE polymorphism tested as independent predictors. We also investigated the combined effect of these polymorphisms on risk for plaque.

RESULTS

The odds ratio for carotid plaque positivity was increased to 3.72 by the a allele of the intron 4 polymorphism and increased to 3.36 by the C allele of the T(-786)-->C polymorphism, but was not increased in subjects with the T allele of the Glu298Asp polymorphism or those with the epsilon4 allele of the apoE polymorphism. However, the odds ratio for plaque positivity was significantly increased to 4.00 by possession of the a allele and/or epsilon4 allele and also increased to 4.04 by the C allele and/or epsilon4 allele.

CONCLUSION

This cross-sectional study showed a synergistic effect between the intron 4 polymorphism or T(-786)-->C polymorphism of the eNOS gene and the apoE polymorphism with respect to risk for carotid atherosclerosis in nondiabetic hemodialysis patients.

Apolipoprotein and apolipoprotein receptor genes, blood lipids and disease

PURPOSE OF REVIEW

Apolipoproteins and their receptors are the main controllers of lipid metabolism and, as such, have a major impact not only on the risk of cardiovascular disease but also on the development and degeneration of the central nervous system. Variations in the genes coding for these apolipoproteins and their receptors and the interaction with the environment determine individual susceptibility to metabolic disturbances, the response to dietary or pharmacological intervention and, finally, to disease.

RECENT FINDINGS

This review will focus on recent findings, such as the latest concepts regarding apolipoprotein E in neurodevelopment, the newly identified apolipoprotein A-V and its influence in triglyceride metabolism, and the improved understanding of apolipoprotein A-I and HDL metabolism in the light of the discovery of the ABC family of transporters. Other key aspects of lipoprotein metabolism and cardiovascular disease risk such as apolipoprotein B-100, the LDL receptor, apolipoprotein C-III or apolipoprotein (a) will be updated.

SUMMARY

Variations in these genes will be analysed in relation to plasma lipid levels, their interactions with diet, treatment or other environmental stimuli, and their influence on the risk of cardiovascular disease and neurological disorders.

The epsilon 2 and 4 alleles of apolipoprotein E and ischemic vascular events in the Greek population--implications for the interpretation of similar studies

The authors investigated whether apolipoprotein (apo) E polymorphism has an allelic and/or genotypic impact on the risk of an ischemic vascular event (IVE) in Greek patients with cardiovascular diseases (CVD). They compared apo E polymorphisms in 1) a group of 165 patients with IVE [IVE(+)], of whom 107 had survived a myocardial infarction and 58 an ischemic stroke; 2) a group of 165 patients, matched with the first group for age and gender, with angiographically confirmed coronary artery disease but without IVE [IVE(-)]; 3) a group of 240 healthy younger individuals with no family history of CVD. The apo epsilon2 allele was 5.2-fold less frequent in the IVE(+) group compared to the IVE(-) group (1.2% vs 6.2%, p = 0.001). The frequency of the epsilon2 allele in healthy subjects was 8.1%, which is 6.7-fold higher than in the IVE(+) group (p < 0.001), and more than twice as high compared to all CVD patients (p = 0.001). No significant differences in epsilon4 allele frequencies were observed between IVE(+) and IVE(-) patients (9.8% vs 8.4%) or between patients with CVD and healthy subjects (9.1% vs 10.2%). The epsilon4 allele was not associated with an increased risk for CVD or IVE. In contrast, an inverse and beneficial association of the epsilon2 allele with IVE was observed among Greek patients with CVD. These results suggest that the epsilon4 and epsilon2 alleles have a variable significance in terms of predicting the risk of vascular events in different populations. Therefore, it is important to carry out "local" studies.

Apolipoprotein E polymorphism and atherosclerosis

The relationship between apolipoprotein (apo) E and vascular disease has been the subject of a considerable amount of research. However, this relationship is far from clearly defined. This deficiency appears to be due to a multitude of factors. Among these are differences in ethnicity, age (and possibly gender), diagnostic criteria, and environmental factors (eg, diet and smoking) that have contributed to the contradictory findings. Several diseases and their treatment may also influence this relationship. There are also documented interactions between apo E genotypes and other genes or vascular risk factors. One possible clinically relevant application of identifying the apo E genotype could be to assess the response to a particular drug treatment. It may also be that apo E polymorphism will become a good predictor of vascular death (eg, from myocardial infarction or stroke) rather than an indicator of the risk of developing vascular disease but without an acute ischemic event. More research is required to define the place of apo E genotyping in the management of vascular disease in its various forms. Whatever the future brings, the evaluation of apo E genotypes will need to be rapid, cheap, and technically undemanding before this investigation becomes widely available and clinically relevant.

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.