Apoprotein E polymorphism and coronary artery disease. Increased prevalence of apolipoprotein E-4 in angiographically verified coronary patients

Apolipoprotein-E Gene Polymorphism and Lipid Composition among IUGR and AGA Neonates

Objective  The objective of this study is to study the profile of apolipoprotein E ( APOE ) gene polymorphism and lipid profile among intrauterine growth restriction (IUGR) and appropriate for gestational age (AGA) neonates. This is an observational study. This study was done at the neonatal unit of a teaching hospital in South India. All consecutively born IUGR neonates (cases) of more than 32 weeks' gestational age and AGA neonates (controls) were enrolled for the study. Genomic DNA extraction was done from a total of 102 peripheral venous blood samples. Genotyping of the APOE rs429358 and rs7412 defining the ε2, ε3, and ε4 alleles was done by polymerase chain reaction-restriction fragment length polymorphism method. Prefeed venous blood was collected and analyzed for lipid profile estimation. The allelic frequencies of cases versus control were ε2-9 (8.7%) versus 3 (2.9%); ε3-88 (84.6%) versus 81 (79.4%); and ε4-7 (6.7%) versus 18 (17.6%). The frequency of ε4 isoform allele, associated with adult onset of metabolic diseases was less among the IUGR group. The mean total cholesterol (TC), Low-Density Lipoprotein (LDL), High-Density Lipoprotein, and triglyceride (TG) were 107.59 ± 35.99, 51.69 ± 24.68, 21.75 ± 9.58, and 151.22 ± 61.84 mg/dL, respectively, in the IUGR group. The mean TC and LDL levels in IUGR group were marginally higher than AGA neonates (107 ± 35.99 vs. 100.37 ± 22.69 mg/dL and 51.69 ± 24.68 versus 46.9 ± 19.51 mg/dL, p  > 0.05). In both groups, the mean TC and TGL levels were elevated in the ε4 isoform subgroup ( p  > 0.05). In our study, the ε2 allele was the second most predominant APOE isoform and the ε4 allele of the APOE gene associated with adult-onset diseases was not increased among IUGR neonates. Neonates with ε4 allele showed an abnormal lipid profile in both study groups suggesting a possible association.

Machine Learning Approach for Cardiovascular Risk and Coronary Artery Calcification Score

Coronary artery calcification (CAC) could assist in the discovery of new risk elements for coronary artery disorder. CAC evaluation, on the other hand, is difficult due to the wide range of CAC in the populations. As a reason, evaluating and analysing data among research have become complicated. In the Research of Inherited Risk Factors for Coronary Atherosclerosis, we used CAC information to test the effects of different analytical methodologies on the correlation with recognized cardiovascular risk elements in asymptomatic patients. Cardiac computed tomography (CT) is also seeing an increase in examinations, and machine learning (ML) could assist with the growing amount of extracted data. Furthermore, there are other sectors in cardiac CT where machine learning could be crucial, including coronary calcium scoring, perfusion, and CT angiography. The establishment of risk evaluation algorithms based on information from CAC utilizing machine learning could assist in the categorization of patients undergoing cardiovascular into distinct risk groups and effectively adapt their treatments to their unique situations. Our findings imply that for forecasting CVD occurrences in asymptomatic people, age-sex segmentation by CAC percentile rank is as effective as absolute CAC scoring. Longitudinal population-based investigations are currently underway and would offer further definitive findings. While machine learning is a strong technology with a lot of possibilities, its implementations in the domain of cardiac CAC are generally in the early stages of development and are not currently commonly accessible in medical practise because of the requirement for substantial verification. Enhanced machine learning will, however, have a significant effect on cardiovascular and coronary artery calcification in the upcoming years.

Coronary Heart Disease in Type 2 Diabetes Mellitus: Genetic Factors and Their Mechanisms, Gene-Gene, and Gene-Environment Interactions in the Asian Populations

Asians are more susceptible to type 2 diabetes mellitus (T2D) and its coronary heart disease (CHD) complications than the Western populations, possibly due to genetic factors, higher degrees of obesity, insulin resistance, and endothelial dysfunction that could occur even in healthy individuals. The genetic factors and their mechanisms, along with gene-gene and gene-environment interactions associated with CHD in T2D Asians, are yet to be explored. Therefore, the objectives of this paper were to review the current evidence of genetic factors for CHD, summarize the proposed mechanisms of these genes and how they may associate with CHD risk, and review the gene-gene and gene-environment interactions in T2D Asians with CHD. The genetic factors can be grouped according to their involvement in the energy and lipoprotein metabolism, vascular and endothelial pathology, antioxidation, cell cycle regulation, DNA damage repair, hormonal regulation of glucose metabolism, as well as cytoskeletal function and intracellular transport. Meanwhile, interactions between single nucleotide polymorphisms (SNPs) from different genes, SNPs within a single gene, and genetic interaction with environmental factors including obesity, smoking habit, and hyperlipidemia could modify the gene's effect on the disease risk. Collectively, these factors illustrate the complexities of CHD in T2D, specifically among Asians.

Effects of exercise training on stroke risk factors, homocysteine concentration, and cognitive function according the APOE genotype in stroke patients

The apolipoprotein E (APOE) gene has been suggested to be associated with stroke and dementia. However, the effects of exercise training on dementia according to the APOE genotype are not consistent to those reported by previous studies. Therefore, we examined the effects of exercise training on stroke risk factors including blood pressure, lipid profiles, homocysteine (Hcy) concentrations, and cognitive function according to the APOE genotype in stroke patients. We examined the stroke risk factors, Hcy, and cognitive function in 28 ischemic stroke patients before and after 6 months of exercise training. After exercise training, body weight, body mass index (BMI), and percent body fat decreased significantly in both APOE groups. According to the APOE genotype, the changes in BMI in the APOE ɛ4 group higher than those in APOE ɛ3 group significantly. Total cholesterol (TC), low-density lipoprotein (LDL)-C, triglyceride (TG), and Hcy decreased and high-density lipoprotein (HDL)-C increased significantly in the both groups. According to the APOE genotype, systolic blood pressure in the APOE ɛ4 group decreased, but in the APOE ɛ3 group increased after exercise training. TC, LDL-C, and TG in the APOE ɛ4 group decreased more extensively than those in the APOE ɛ3 group after exercise training. VO_2max (maximal oxygen consumption) and cognition increased significantly in both groups. Folate acid intake also increased significantly in both groups. The APOE genotype affects variations in the risk factors of stroke after exercise training. However, the Hcy and cognitive function did not differ based on the APOE genotype.

Influence of Apolipoprotein E on the Lipid Profile and Postprandial Triglyceride Levels in Brazilian Postmenopausal Women With Artery Disease

This study confirms the association of risk factors for coronary artery disease (CAD) and the apoE polymorphisms, specifically related to the APOE*4 allele, with coronary disease in postmenopausal women. Significantly altered values of the lipid profile were found in patients when compared with controls, independent of the presence of the APOE*4 allele. However, the controls showed higher high-density lipoprotein cholesterol (HDL-C) levels and reduced triglyceride (TG) levels, differing significantly from patients. In this case, the study of subgroups, considering the APOE*3/3 and APOE*3/4 genotypes, suggests that the APOE*4 allele is not implicated in the variations of the lipid profile of patients and determined an increase in the production levels of HDL-C and a reduction in TG highly benefiting the control group compared with APOE*3/3 genotype. The metabolic kinetics of TG, although with the same pattern between groups, and the presence of the APOE*4 allele are suggested to be associated with accelerated clearance compared with APOE*3 allele in non-CAD group.

Apolipoprotein E gene polymorphism and risk for coronary heart disease in the Chinese population: a meta-analysis of 61 studies including 6634 cases and 6393 controls

BACKGROUND

Numerous studies have evaluated the association between the apolipoprotein E (apoE) gene polymorphisms in coronary heart disease (CHD). However, the results remain uncertain. We carried out a meta-analysis to derive a more comprehensive estimation of the association in Chinese population.

METHODS

Case-control studies in Chinese and English publications were identified by searching databases of PubMed, EMBASE, Web of Science, CNKI, CBM, Wanfang, VIP and hand searching of relevant journals and the reference lists of retrieved articles. Odds ratio (OR) and 95% confidence interval (CI) were applied to assess the strength of the associations. Subgroup analysis and sensitivity analysis were performed to explore the between-study heterogeneity.

RESULTS

We finally identified 61 relevant studies which comprised 6634 case-patients and 6393 controls. The pooled OR for ε4 carriers was 96% higher than the ε3/3 genotype for CHD (OR, 1.96; 95% CI, 1.70 to 2.24; P<0.001). However, there was no evidence of statistically significant association between ε2 carriers and risk of CHD (OR, 1.02; 95% CI, 0.91 to 1.13; P = 0.729). In the subgroup analysis, different endpoints may partially account for the heterogeneity. No publication bias was found.

CONCLUSIONS

Our meta-analysis suggests that the apoE ε4 allele may be a risk factor for CHD in the Chinese population, however, ε2 allele has no significant association.

Reduced memory in fat mass and obesity-associated allele carriers among older adults with cardiovascular disease

BACKGROUND

Much attention has been paid to the prevalence and predisposition of the fat mass and obesity-associated (FTO) gene to obesity, although only a few studies have characterized the extent to which this affects cognitive function. This study examined differences between risk allele carriers (i.e. FTO-AC/AA) and non-carriers (i.e. FTO-CC) on indices of attention/executive function/psychomotor speed, memory, language, and visual-spatial ability in a sample of older patients with cardiovascular disease.

METHODS

We recruited 120 older adults from an outpatient cardiology clinic who underwent blood draw and completed neuropsychological testing. Participants were classified into two groups: one for those who were homozygous for the non-risk-conferring allele (i.e. FTO-CC) (n= 49) and the other for those who had at least one copy of the obesity risk-conferring A allele (i.e. FTO-AC/AA) (n= 71).

RESULTS

Mancova analyses adjusting for age and years of education revealed the FTO-AC/AA group performed significantly worse on indices of memory (λ= 0.94, F(2, 115) = 3.58, P= 0.03, partial η(2) = 0.06). Follow-up tests revealed a significant effect for the FTO-AC/AA group, relative to the non-carrier group, on encoding (i.e. California Verbal Learning Test Total Learning) and California Verbal Learning Test long-delay free recall (P < 0.05). No such differences between FTO carriers and non-carriers emerged on tests of attention/executive function/psychomotor speed, language, or visual-spatial ability (P > 0.05 for all).

CONCLUSIONS

These findings suggest that the FTO risk allele is associated with reduced memory performance, particularly on aspects of memory encoding and delayed recall. To elucidate underlying mechanisms, these findings will need to be replicated in larger samples that utilize neuroimaging.

Apolipoprotein E gene polymorphism: effects on plasma lipids and risk of type 2 diabetes and coronary artery disease

BACKGROUND

The most common apolipoprotein E (apoE) gene polymorphism has been found to influence plasma lipid concentration and its correlation with coronary artery disease (CAD) has been extensively investigated in the last decade. It is, however, unclear whether apoE gene polymorphism is also associated with increased risk of type 2 diabetes mellitus (T2DM). The knowledge of this study may provide the primary prevention for T2DM and CAD development before its initiation and progression. Therefore, this study was carried out to determine the association between apoE gene polymorphism and T2DM with and without CAD and its role in lipid metabolism.

METHODS

The case-control study was carried out on a total of 451 samples including 149 normal control subjects, 155 subjects with T2DM, and 147 subjects with T2DM complicated with CAD. The apoE gene polymorphism was tested by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Univariable and multivariable logistic regression analyses were used to identify the possible risks of T2DM and CAD.

RESULTS

A significantly increased frequency of E3/E4 genotype was observed only in T2DM with CAD group (p = 0.0004), whereas the ε4 allele was significantly higher in both T2DM (p = 0.047) and T2DM with CAD (p = 0.009) as compared with controls. E3/E4 genotype was also the independent risk in developing CAD after adjusting with established risk factors with adjusted odds ratio (OR) 2.52 (95%CI 1.28-4.97, p = 0.008). The independent predictor of individuals carrying ε4 allele still remained significantly associated with both CAD (adjusted OR 2.32, 95%CI 1.17-4.61, p = 0.016) and T2DM (adjusted OR 2.04, 95%CI 1.07-3.86, p = 0.029). After simultaneously examining the joint association of E3/E4 genotype combined with either obesity or smoking the risk increased to approximately 5-fold in T2DM (adjusted OR 4.93, 95%CI 1.74-13.98, p = 0.003) and 10-fold in CAD (adjusted OR 10.48, 95%CI 3.56-30.79, p < 0.0001). The association between apoE genotypes on plasma lipid levels was compared between E3/E3 as a reference and E4-bearing genotypes. E4-bearing genotypes showed lower HDL-C and higher VLDL-C and TG, whereas other values of plasma lipid concentrations showed no significant difference.

CONCLUSIONS

These results indicate that ε4 allele has influence on lipid profiles and is associated with the development of both T2DM with and without CAD, and furthermore, it increased the risk among the subjects with obesity and/or smoking, the conditions associated with high oxidative stress.

Statin use and the risk of Alzheimer's disease: the MIRAGE study

BACKGROUND

The aim of this study was to examine the association between statin use before the onset of Alzheimer's disease (AD) symptoms and risk of having AD, and to explore the potential impact of APOE genotype and race on this association.

METHODS

Data were collected through standardized, validated questionnaires from 895 subjects with probable or definite AD by research criteria, and 1,483 of their nondemented relatives in this family-based, case-control study of AD patients and their relatives enrolled at 15 research centers from 1996 through 2002. To minimize temporal and prescription biases, exposure to statin use within each family was ignored in the one year before the first appearance of AD symptoms in that family's affected member. Associations were estimated using generalized estimating equations for a logistic model, adjusting for age, sex, race, education, history of heart disease, stroke, diabetes, smoking and APOE genotype.

RESULTS

Statin use was associated with lowered odds of having AD (adjusted odds ratio [OR], 0.61; 95% confidence interval [CI], 0.38 to 0.98). Nonstatin cholesterol-lowering medications were not associated significantly with lowered odds of having had AD (adjusted OR, 1.7; 95% CI, 0.61 to 5.0).

CONCLUSIONS

Statin medications were associated with lowered risk of AD in this population. Neither African-American race, nor the presence of the APOE 4 allele modified the statin-AD association.

Differential course of HIV-1 infection and apolipoprotein E polymorphism

We studied the course of infection with human immunodeficiency virus type 1 (HIV-1) in relation to apolipoprotein E (APOE) polymorphism found for 209 Italians treated at Infectious Disease Clinics in Rome and Modena. Clinically, patients were classified into four groups according to the yearly rate of decline in CD4+ cell count (LTNP: long-term non-progression; SLOW, ’NORMAL’ or RAPID). Patients at both extremes of the clinical spectrum, i.e. those who rapidly progressed to AIDS and those with stable high CD4 cell counts, had few APOE ɛ4 and ɛ2 alleles (P = 0.04). Detailed clinical information was then used to construct four model-based clinical profiles using grade-of-membership analysis (GoM), predictive of APOE genotypic frequencies: 1. The clinical profile associated with good long-term prognosis lacked ɛ2 (P=0.01); 2. Disease progression to AIDS was associated with ɛ4 and ɛ2, most evident for zidovudine-lamivudine regimens without a protease inhibitor (P = 0.03); and, 3. AIDS patients had low ɛ4 and ɛ2 frequencies, consistent with a high mortality rate among ɛ4+ and ɛ2+ AIDS patients. These findings suggest allele-specific immunomodulatory effects involving inherited APOE isoform important enough to alter the clinical course of HIV infection and, possibly, drug efficacy. They imply a connection between lipid metabolism and immunity potentially relevant to common disorders.

Blood leukocyte count is a risk factor for intima-media thickening and subclinical carotid atherosclerosis in middle-aged men

Leukocytosis is known to predict future cardiovascular events even in subjects without coronary heart disease (CHD), but its association with early atherosclerotic changes has remained less certain. The aim of the present study was to investigate how the blood leukocyte count compares with several other risk factors for CHD in determining carotid artery intima-media thickness (IMT) and subclinical carotid atherosclerosis in a population sample. Both carotid arteries were investigated with high-resolution B-mode ultrasound in a community-based sample of 219 randomly selected men aged 50-59 years to calculate the mean maximum IMT (MMax IMT) of 12 standard sites. Risk factor assessment included several traditional biochemical risk factors, blood pressure, maximal oxygen consumption and work load on ergometry, life-style habits and hematologic parameters. As genetic determinants, apolipoprotein E and A-IV polymorphisms were studied. According to multivariate regression analysis, age (P<0.0001), blood leukocyte count (P<0.0001) and systolic blood pressure (P<0.042) were the only significant predictors of MMax IMT. MMax IMT increased linearly from the lowest tertile of blood leukocyte count (1.14+/-0.20mm) to the second (1.18+/-0.25 mm) and to the highest tertile (1.25+/-0.27 mm, P=0.019). This difference remained significant after adjustment with age, systolic blood pressure and smoking (P=0.032). Leukocytes seem to have an independent role in the early arterial damage and they may reflect subclinical disease. This implies that leukocyte count is undervalued in the diagnostics and prognostics of carotid atherosclerosis.

Apolipoprotein E, cardiovascular disease and cognitive function in aging women

The apolipoprotein E (APOE) e4 allele increases risk of Alzheimer disease and cardiovascular diseases. We examined APOE genotypes alone or combined with cardiovascular conditions in relation to cognitive function in 4227 Nurses' Health Study participants, 70-80 years old. From 1995 to 2001, and again 2 years later, participants received telephone cognitive assessments of general cognition, category fluency, verbal memory and working memory. In biennial questionnaires since 1976, participants have provided extensive health information including cardiovascular conditions. Compared with women with the e3/3 genotype, e4 carriers performed worse at baseline across all tests (mean global composite score was lower by 0.10 points (95% confidence interval=-0.15, -0.05)) and declined more (mean change in global score was -0.07 points (95% CI=-0.12, -0.03)), with a strong allele dose-response trend (P-trend=0.0003). Among participants 75+ years, e2 carriers performed best. Women with an e4 allele and cardiovascular conditions such as transient ischemic attack or untreated hypertension had the worst cognition. Thus, APOE genotypes strongly influenced cognitive function and decline; prevention of cardiovascular disease may limit these effects.

Lack of genetic association of cholesteryl ester transfer protein polymorphisms with late onset Alzheimers disease

Dysregulation of cholesterol homeostasis may be associated with the pathogenesis of coronary artery disease (CAD) and Alzheimers disease (AD). Recently, several single nucleotide polymorphisms (SNPs) in cholesteryl ester transfer protein (CETP) were associated with altered plasma CETP concentrations, cholesterol concentrations and CAD. Hence, these CETP SNPs represent excellent candidates for evaluating association with AD. To date, one study has evaluated the association between a single CETP SNP and AD. In this study, we examined three CETP SNPs to evaluate the genetic association of CETP with late onset AD on two study cohorts: the Religious Orders Study (ROS) series, including 85 AD and 70 non-AD individuals, and the University of Kentucky (UKY) series, including 78 AD and 84 non-AD individuals. Significant association between CETP genotypes or haplotypes and late onset AD was not detected in these two study cohorts. Moreover, the CETP genotypes and haplotypes were not significantly associated with AD when the populations were stratified for the presence or absence of apolipoprotein E4 (apoE4). In summary, CETP genetic variants were not associated with AD in two series.

Genetic determinants of arterial calcification associated with atherosclerosis

Increasing research interest has focused on arterial calcification in the setting of atherosclerosis. Many features of atherosclerosis-related calcification provide useful clinical information. For example, calcium mineral deposits frequently form in atherosclerotic plaque, and intimal arterial calcification can be used as a surrogate marker for atherosclerosis; also, calcium deposits are readily and noninvasively quantified, which is useful because greater amounts of coronary calcification predict a higher risk of myocardial infarction and death. Several mechanisms leading to calcification associated with atherosclerosis have been proposed; however, no direct testing of proposed mechanisms has yet been reported. Studies in genetically altered animals and in humans have shed light on potential genetic determinants, which in turn could form the basis for a more comprehensive understanding of the factors affecting calcification within plaque and the associated pathobiologic implications. We review proposed molecular and cellular mechanisms of atherosclerosis-associated arterial calcification, summarize genetic influences, and suggest areas in which further investigation is needed. Understanding the molecular and genetic determinants of specific structural plaque components such as calcification can provide a solid foundation for the development of novel therapeutic approaches to favorably alter plaque structure and minimize vulnerability to arterial rupture.

The renin-angiotensin-aldosterone system and Alzheimer s disease?

Epidemiological studies from the last decade have begun to produce evidence that the perceived joint occurrence of vascular disease and Alzheimer's disease (AD), both common elderly disorders more often believed to occur by chance due to their high prevalence, may now actually have a more pathological significance. The following review discusses some of this evidence and the implications for cognitive decline and the development of AD and how a well-known cardiovascular risk factor gene, the apolipoprotein E (APOE) gene, plays a significant role in the molecular genetics of AD. It also introduces and discusses recent and compelling evidence for the involvement of another well-known cardiovascular risk factor gene, the angiotensin-converting enzyme (ACE1) gene, in the pathogenesis of AD. This role is suggested in terms of recent molecular genetic association evidence implicating the ACE1 insertion/deletion (indel) polymorphism, a more recent large haplotype study that greatly extends the ACE1 indel evidence and incorporates knowledge accrued from previous cardiovascular disease-focused ACE1 haplotype studies. Finally, this paper discusses very recent biological evidence that further supports a role for ACE1 and hypothesises a number of readily testable mechanisms by which the ACE1 enzyme and other components of the renin-angiotensin-aldosterone system may be implicated in increased risk and/or the progression of AD.

Influence of the polymorphism of apolipoprotein E in cerebral vascular disease

The genetic heterogeneity of apolipoprotein E (apo E) has been associated with lipid profile and atherothrombotic stroke, however this association remains inconclusive.

OBJECTIVE

To evaluate the relationship between the isoforms of apo E and atherothrombotic stroke, by ascertaining the frequency of its alleles and genotypes associated with the lipid profile in patients with stroke.

METHOD

A total of 207 individuals were divided into two groups, consisting of 107 patients with stroke and 100 individuals without clinical symptoms of the disease. Blood samples were taken from patients and controls for molecular investigation of the apo E (epsilon2, epsilon3 and epsilon4 alleles) for the analysis of the lipid profile.

RESULTS

The epsilon3 allele was the most common and its prevalence was significantly higher in patients (0.93) compared to the controls (0.86; p=0.024). The epsilon2 allele was rarely seen specifically in patients (0.02 versus 0.05 in controls, p=0.191). The epsilon4 allele was not associated with stroke showing a reduced frequency in patients (0.05) when compared to controls (0.09; p=0.011). Although higher average levels of lipid profile were found in patients when compared to controls, with statistical significance for the values of total cholesterol (TC) (203.6 mg/dL +/- 57.98 and 181.9 mg/dL +/- 68.47 respectively; p=0.003) and low-density lipoprotein cholesterol (LDLc) (131.4mg/dL +/- 52.60 and 116 mg/dL +/- 56.38, respectively; p=0.014), these were independent of the presence of the epsilon4 allele. In control group the higher TC and LDLc values occurred in the absence of the epsilon4 allele, confirming the conflicting effect of the alleles of apo E on the plasmatic lipids and atherothrombotic stroke.

CONCLUSION

The isoforms of apo E cannot be regarded as an isolated risk factor for stroke and do not show association with lipid profile in this study.

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.

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.

Contributions of 18 additional DNA sequence variations in the gene encoding apolipoprotein E to explaining variation in quantitative measures of lipid metabolism

Apolipoprotein E (ApoE) is a major constituent of many lipoprotein particles. Previous genetic studies have focused on six genotypes defined by three alleles, denoted epsilon2, epsilon3, and epsilon4, encoded by two variable exonic sites that segregate in most populations. We have reported studies of the distribution of alleles of 20 biallelic variable sites in the gene encoding the ApoE molecule within and among samples, ascertained without regard to health, from each of three populations: African Americans from Jackson, Miss.; Europeans from North Karelia, Finland; and non-Hispanic European Americans from Rochester, Minn. Here we ask (1) how much variation in blood levels of ApoE (lnApoE), of total cholesterol (TC), of high-density lipoprotein cholesterol (HDL-C), and of triglyceride (lnTG) is statistically explained by variation among APOE genotypes defined by the epsilon2, epsilon3, and epsilon4 alleles; (2) how much additional variation in these traits is explained by genotypes defined by combining the two variable sites that define these three alleles with one or more additional variable sites; and (3) what are the locations and relative allele frequencies of the sites that define multisite genotypes that significantly improve the statistical explanation of variation beyond that provided by the genotypes defined by the epsilon2, epsilon3, and epsilon4 alleles, separately for each of the six gender-population strata. This study establishes that the use of only genotypes defined by the epsilon2, epsilon3, and epsilon4 alleles gives an incomplete picture of the contribution that the variation in the APOE gene makes to the statistical explanation of interindividual variation in blood measurements of lipid metabolism. The addition of variable sites to the genotype definition significantly improved the ability to explain variation in lnApoE and in TC and resulted in the explanation of variation in HDL-C and in lnTG. The combination of additional sites that explained the greatest amount of trait variation was different for different traits and varied among the six gender-population strata. The role that noncoding variable sites play in the explanation of pleiotropic effects on different measures of lipid metabolism reveals that both regulatory and structural functional variation in the APOE gene influences measures of lipid metabolism. This study demonstrates that resequencing of the complete gene in a sample of >/=20 individuals and an evaluation of all combinations of the identified variable sites, separately for each population and interacting environmental context, may be necessary to fully characterize the impact that a gene has on variation in related traits of a metabolic system.

Apolipoprotein E gene polymorphism in cerebrovascular disease: a case-control study

The association between apolipoprotein E (apo E) polymorphism and stroke has been controversial. So far there are no studies reported on the polymorphism of apolipoprotein E in cerebrovascular diseases in the Asian Indians. A blinded case-control study was therefore undertaken and the apo E genotypes and lipid profile of a total of 120 subjects (63 stroke patients and 57 healthy controls) were done. The frequency distribution of apo E alleles and genotypes were assessed and their relation with the occurrence of stroke in Asian Indian subjects was determined. A significantly high frequency of apo epsilon4 allele (30%) was observed in the stroke patients than the controls (11%) (p < 0.005), and patients with epsilon4 allele had a fourfold higher odds to develop stroke OR (95%CI) 4.2 (1.8-10.1) (p < 0.005). On multivariate analysis, after adjusting for age, triglycerides and hypertension, the association of epsilon4 allele with stroke was found to be no longer statistically significant, OR (95%CI) 1.2 (0.4-4.5) (p = NS). On multiple logistic regression analysis age, OR (95%CI) 1.1 (1.1-1.2) (p < 0.001), and hypertension OR (95%CI) 15.1 (2.6-89.1) (p < 0.005) were found to be independent risk factors for development of stroke. This is the first report to have examined the association of apo E gene polymorphism with stroke in the Asian Indians. This study suggests that apo epsilon4 allele, triglycerides, age and hypertension are the predictors for stroke development.

Apolipoprotein E polymorphism in Northern Indian patients with coronary heart disease: phenotype distribution and relation to serum lipids and lipoproteins

Apolipoprotein E (apo E), a genetic determinant of plasma lipid levels and coronary heart disease (CHD) needs to be investigated in Asian Indians since they have a propensity to develop dyslipidemia and accelerated atherosclerosis. We studied apo E phenotypes and plasma lipid levels in 52 Northern Indian male patients (aged 38-71 years) with angiographically proven CHD, and compared them to 50 healthy blood donors taken as the control group. High levels of Lp(a), (p < 0.05), and a definite trend towards lower levels of HDL-C (p < 0.05), was observed in the CHD patients as compared to the control subjects. The frequency of apo E allele epsilon3 was 0.86 and 0.862, and epsilon4 allele was 0.12 and 0.08 in the patients and controls, respectively. However, a lower frequency of the E2 allele was observed in the patient group (E2 = 0.02) as compared to the controls (epsilon2 = 0.06) (p = ns). In individuals with apo E3/E3 phenotype, significantly lower HDL-C levels was observed in the CHD patients as compared to the control subjects (p < 0.05). A positive correlation was observed between apo E phenotypes and Lp(a) levels in the CHD subjects as compared to the controls (p < 0.05), the level being significantly high in CHD subjects with at least one E4 allele. To conclude, in this sample of Northern Indian subjects with CHD, there is a significant correlation between apo E3/E3 phenotype and low levels of HDL-C as compared to the control subjects. Further, apo E phenotype is positively correlated with high Lp(a) levels in the CHD subjects having at least one E4 allele. However, these relationships need to be explored in a larger sample of subjects.

Association of apolipoprotein E polymorphism with myocardial infarction in Greek patients with coronary artery disease

Studies in several populations have indicated that genetic variation at the apolipoprotein E (apoE) structural locus influences the risk of coronary artery disease (CAD) and myocardial infarction (MI). This study aimed at investigating whether apoE polymorphism has an allelic and/or genotypic impact on the risk of MI in Greek patients with CAD. We compared apoE gene polymorphism in a group of patients with angiographically confirmed CAD but not MI [CAD/MI (-)-group, n = 143] and a group of age and sex-matched CAD patients who had experienced a non-fatal Ml [CAD/MI (+)-group, n = 124]. The patients were also compared with a group of healthy younger individuals (n = 240) with no family history of CAD. The apoE genotype distribution differed significantly between the two groups of CAD patients (p = 0.02). The epsilon2 allele was 5.3-fold less frequent in the CAD/ MI (+)-group compared with the CAD/MI (-)-group (1.2% vs. 6.3%, p = 0.01). The frequency of the epsilon2 allele in healthy subjects was 8.1%, which is 6.8-fold higher than in CAD/MI (+)-patients (p = 0.001) and twice as high compared with all CAD patients (p = 0.02). No differences in epsilon4 allele frequencies were observed between CAD/MI (+)- and CAD/MI (-)-patients (10.9% vs. 9.8%), or between patients with CAD and healthy subjects (10.3% vs. 10.2%). In summary, the epsilon4 allele was not found to be associated with an increased risk for CAD or MI. In contrast, a negative association of the epsilon2 allele with Ml was observed among Greek patients with CAD.

Physical activity may modulate effects of ApoE genotype on lipid profile

Increased levels of physical activity may improve the lipid profile, but is this effect identical across apolipoprotein E (apoE) genotypes? A population-based cross-sectional survey conducted from 1999 to 2000 included 1708 randomly selected men and women aged 35 to 74 years. A validated physical activity questionnaire measured, for each participant, the total energy expenditure and its percentage used in high-intensity activities (%high-intensity activity), eg, brisk walking and sports. The effects of the apoEx%high-intensity activity interaction on the lipid profile were investigated by using multiple linear regression models. Among men, increased %high-intensity activity had greater protective effects in the apoE4 group regarding (1) high density lipoprotein (HDL) cholesterol (P<0.001), compared with either the apoE2 (interaction P=0.05) or apoE3 (interaction P<0.03) groups, and (2) triglycerides (P<0.03), compared with the apoE3 group (interaction P=0.07). A 10% increase of %high-intensity activity by an apoE4 man would correspond with a 0.07-mmol/L increase in HDL cholesterol and a -0.15-mmol/L decrease in triglycerides. Among women, only the protective effects of physical activity on HDL cholesterol in the apoE4 group versus the apoE2 group was statistically significant. Spending a larger fraction of the total energy expenditure in high-intensity activities may counteract the atherogenic effects of the epsilon4 allele on the lipid profile.

Apolipoprotein E4 polymorphism as risk factor for coronary heart disease among Indian subjects

Apolipoprotein E genotypes and lipid and lipoprotein levels were determined in hypercholesterolemic and angiographically vertified CHD subjects and compared against 90 normolipidemic controls. The ε4 allele was significantly prevalent in the hypercholesterolemic and CHD subjects. Significant increase in total cholesterol levels in apo ε4 containing subjects were observed in the hypercholesterolemic and CHD group. The study suggests that the ε4 allele by influencing the lipid levels could act as a risk factor for CHD.

Effects of apolipoprotein E genotypes and other risk factors on the development of coronary artery disease in Southern Turkey

BACKGROUND

Apolipoprotein E (apoE) plays a major role in lipoprotein metabolism and lipid transport. Associations between apoE genotypes, coronary artery disease (CAD) and other risk factors have been described by many investigators. The aim of this study was to investigate the role of apoE gene polymorphism and other risk factors in the development of CAD in subjects whose coronary arteries were evaluated by means of coronary angiography.

METHODS

The study population consisted of 199 subjects (114 male and 55 female). Of the total, 107 had CAD. The apoE gene was amplified by polymerase chain reaction (PCR) and then digested by CfoI restriction enzyme. The plasma lipid levels and other risk factors were also determined in all subjects.

RESULTS

The epsilon2 and epsilon4 allele frequencies and genotypes carrying epsilon4 allele were significantly higher in CAD (+) patients. Plasma lipids except triglycerides were increased in CAD (+) cases. We found that apoE genotypes, HT, DM, male gender, age and smoking were the independent predictors of CAD. There was no association between apoE alleles and lipids.

CONCLUSION

We conclude that apoE polymorphism (presence of epsilon4 allele) is associated with the development of CAD in Southern Turkey. In our study, we did not observe any effect of apoE alleles on lipid levels.

Familial hypercholesterolaemia in Finland: common, rare and mild mutations of the LDL receptor and their clinical consequences. Finnish FH-group

Familial hypercholesterolaemia (FH) is an autosomal co-dominantly inherited condition resulting from mutations of the low-density lipoprotein (LDL) receptor which occur in heterozygous form in approximately one in 500 individuals. Clinically, FH is characterized by 2-3-fold elevation of serum LDL cholesterol levels, accelerated development of atherosclerotic vascular disease, and, if untreated, shortened lifespan. The Finnish population, which represents a genetic isolate, offers exceptional possibilities for genetic-epidemiological studies on FH, as a handful of founder gene mutations account for the majority of FH cases in Finland. This review summarizes data from our FH studies carried out since 1985. We wish to emphasize the continuum of genotype-phenotype relationships, the importance of molecular diagnosis, the detection of novel risk factors of vascular disease, and innovations inhibiting cholesterol absorption for the modern treatment of FH.

The apolipoprotein epsilon2 allele and the severity of coronary artery disease in Type 2 diabetic patients

AIMS

To examine the hypothesis that apolipoprotein E2 is associated with more severe coronary disease in Type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

In this retrospective cohort study, 491 patients with angiographically assessed coronary disease were recruited from those attending a university hospital cardiology department. Participants completed detailed questionnaires, from which the presence or absence of diabetes was determined. Fasting blood samples were obtained for apolipoprotein E genotype and measurement of blood lipid parameters.

RESULTS

The prevalence of triple vessel disease was significantly lower in non-diabetic, epsilon2 allele carriers (39.3% vs. 16.2%; odds ratio (OR) 0.30 (0.12-0.71), P < 0.03) compared with E3/3 carriers. In Type 2 diabetic patients, epsilon2 allele carriers had an excess of triple vessel disease compared with E3/3 genotypes (43.3 vs. 68.8%; OR 2.8 (1.07-7.30), P < 0.05). The differences were independent of other variables. The apo E4 subgroup showed no significant differences in the frequency of triple vessel disease.

CONCLUSIONS

Diabetic epsilon2 allele carriers had more severe coronary artery disease than diabetic patients with other apo E isoforms. In non-diabetic patients the epsilon2 allele appeared to protect against severe coronary disease. We hypothesize that interaction between the diabetic milieu and the epsilon2 allele accelerates plaque progression. It suggests that diabetic patients who are carriers of the epsilon2 allele, even in the heterozygous form, should be the focus of particular therapeutic attention. Diabet. Med. 18, 445-450 (2001)

Apolipoprotein E genotype and cardiovascular disease in the Framingham Heart Study

BACKGROUND

Apolipoprotein (apo) E is a constituent of lipoproteins with considerable variation due to cysteine-arginine exchanges. The apo E4 (Arg112-Cys) polymorphism has been associated with dementia and hypercholesterolemia. We investigated the relation of APOE genotype to cardiovascular disease (CVD) in the Framingham Offspring Study.

METHODS AND RESULTS

DNA was isolated from 3413 study participants and APOE genotypes were determined utilizing the polymerase chain reaction and restriction isotyping. In the entire group of subjects, 20.7% had apo E4/4 or E3/4 (Group E4); 14.1% had apo E2/2 or E2/3 (Group E2) and 63.9% had the apo E3/3 genotype (Group E3). Subjects with E2/4 (1.3%) were excluded. Period prevalence of CVD between examinations 1 and 5 (1971-1994) (366 events) was related to APOE genotype. Age adjusted period prevalence of CVD in men was 18.6% for Group E4, 18.2% for Group E2 and 12.7% for Group E3 (P=0.004); while in women these rates were 9.9, 4.9, and 6.6%, respectively (P=0.037). After adjustment for non-lipid risk factors the relative odds for CVD in Group E2 men was 1.79 (P=0.0098) and in Group E4 it was 1.63 (P=0.0086) compared with the Group E3; while in Group E4 women it was 1.56 (P=0.054). After adjustment for all CVD risk factors, the relative odds in Group E2 men was 1.94 (P=0.004) and in Group E4 men it was 1.51 (P=0.0262).

CONCLUSIONS

The presence of the apo E2 or apo E4 alleles in men is associated with significantly greater CVD risk. This genotypic information may help to identify individuals at increased risk for CVD events.

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.

Apolipoprotein epsilon2 allele is associated with an anti-atherogenic lipoprotein profile in children: The Columbia University BioMarkers Study

OBJECTIVE

We examined associations between allelic variation in the apo epsilon gene, which codes for apolipoprotein E, and plasma lipid levels in children.

MATERIALS AND METHODS

We analyzed genotype and fasting lipid levels, including lipid particle size by nuclear magnetic resonance spectroscopy, in 515 children from 297 families.

RESULTS

Children carrying the apo epsilon2 allele (1 or 2 epsilon2 alleles; n = 45) had higher mean high-density lipoprotein (HDL) cholesterol level (49.5 +/- 13.0 vs 42.4 +/- 8.9 mg/dL) and lower mean low-density lipoprotein (LDL) cholesterol level (82.2 +/- 48.6 vs 105.9 +/- 45.0 mg/dL) compared with apo epsilon3/epsilon3 children (n = 322). Mean HDL size was larger and mean level of the atheroprotective large HDL subpopulation was higher among apo epsilon2 carriers compared with epsilon3/epsilon3 children (9.5 +/- 0.4 vs 9.3 +/-.4 nm, and 32.8 +/- 9.9 vs 27.6 +/- 8.2 mg/dL). In multivariate models adjusting for age, sex, ethnicity, family history, body mass index, and fasting triglyceride level, the apo epsilon2 allele was independently predictive of higher levels of HDL cholesterol and the large HDL subpopulation and of lower level of LDL cholesterol.

CONCLUSION

The apo epsilon2 allele is associated with an anti-atherogenic lipid pattern in children.apolipoprotein epsilon, children, cholesterol.

Genetic variations of the apolipoprotein E gene determine the plasma triglyceride levels after heart transplantation

OBJECTIVES

To study whether the presence of the polymorphism in the apolipoprotein E (apo E) gene influences the lipid profile in heart-transplant recipients.

METHODS

A cohort of 103 recipients of heart transplant (93 men and 10 women, with a mean age of 47 +/- 13 years) under triple immunosuppressive therapy were submitted to a genetic study of the apo E gene region. Anthropometric and analytical data, including lipid profile and arterial blood pressure were collected prior to transplantation and 3, 6, 12, and 24 months after it.

RESULTS

65 subjects present the genotype E3E3, 27 the genotype E3E4, 6 the genotype E2E3, and 5 the genotype E2E4. Carriers of the E2 allele (that is, genotypes E3E2 and E4E2) had higher total plasma triglyceride (TG) levels after 3 months (3.47 +/- 1.88 mmol/liter p < 0.001) and after 1 year of transplantation (3.13 +/- 1.77 mmol/liter p < 0.05) than the other genotypes. There were no differences in the plasma levels of total cholesterol (TC), LDL-cholesterol (LDL-C), and HDL-cholesterol (HDL-C). Multiple regression analysis revealed that the apoprotein E gene polymorphism determines 5% (p = 0.0425) and age 8.7% (p < 0.009) of the variants in TG levels.

CONCLUSIONS

The presence of the E2 allele in heart-transplant recipients produces a greater rise in total TG plasma levels than the other genotypes.

Apolipoprotein E phenotype, arterial disease, and mortality among older women: the study of osteoporotic fractures

This study is an investigation of the relationship between apolipoprotein E (apoE) phenotype, arterial disease, and mortality in a group of women (n = 1,751) aged 65 years and older enrolled in the Study of Osteoporotic Fractures. Crude mortality rates were highest among women with the 4-3 and 4-4 phenotypes but age-adjusted mortality showed no statistically significant variations across the phenotype groups. Using multivariate analysis, the mortality experience of women with 4-3 or 4-4 apoE phenotypes was compared to that of women with the 3-3 phenotype: no significant excess total mortality was found [relative risk (RR) = 1.2, 95% confidence interval (CI) 0.8, 1.8] among women with the epsilon 4 allele. Similarly, neither cardiovascular (RR = 0.9. 95% CI 0.5, 1.8) nor cancer (RR = 1.5, 95% CI 0.8, 2.8) mortality rates were significantly different in this group of women. Inclusion of cholesterol levels in the regression models did not change the relative mortality risks. Among women 65-69 year of age epsilon 4 was associated with an approximate doubling of RR for death due to both cardiovascular disease and cancer. No association was found between apoE phenotype and the presence of lower extremity arterial disease (defined as an ankle/arm index of 0.9 or less). These results suggest that women with the epsilon 4 who survive to age 70 years or beyond have a life expectancy that is similar to that for women homozygous for the 3 allele who comprise the majority of the population.

Acute myocardial infarction in young adults: prognostic role of angiotensin-converting enzyme, angiotensin II type I receptor, apolipoprotein E, endothelial constitutive nitric oxide synthase, and glycoprotein IIIa genetic polymorphisms at medium-term follow-up

BACKGROUND

A number of reports have investigated the association between various gene polymorphisms and the phenotypic expression of myocardial infarction. No investigations have evaluated the prognostic role of genetic factors in young people with premature coronary disease. The aim of this study was to investigate the influence of genetic factors compared with that of conventional risk factors on follow-up events in a population of Italian young adults with myocardial infarction.

METHODS AND RESULTS

The study population consisted of 106 young patients (mean age 40 +/- 4 years, range 23 to 45 years) with diagnosis of acute myocardial infarction. Clinical and genetic data from the group of patients with events during follow-up were compared with those from patients without events. The following genetic polymorphisms were tested: angiotensin I converting enzyme, angiotensin II type I receptor, apolipoprotein E (ApoE), endothelial constitutive nitric oxide synthase, and platelet glycoprotein IIIa. Coronary angiography was performed in 94 patients. Coronary angiography showed coronary artery disease in 93% of patients. During follow-up (46 +/- 12 months, range 25 to 72) the overall combined end points (cardiac death, myocardial infarction, and revascularization procedures) accounted for 21 events. Family history of coronary artery disease, smoking, stenosis of the left anterior descending artery at coronary angiography, and ApoE polymorphism (presence of epsilon4 allele) were significantly more prevalent (univariate analysis) in the group of patients with events. Logistic multivariate analysis showed that ApoE polymorphism (P =. 004, odds ratio [OR] 6.8, 95% confidence interval [CI] 2 to 22), family history (P =.005, OR 8.3, 95% CI 2 to 35), smoking after acute myocardial infarction (P =.008, OR 10.9, 95% CI 2 to 62), and left anterior descending coronary artery disease (P =.02. OR 6.6, 95% CI 1.3 to 33) were independent predictors of adverse events.

CONCLUSIONS

Myocardial infarction at a young age is commonly characterized by evidence of multiple cardiovascular risk factors and by a favorable prognosis in short- and medium-term follow-up. Evidence of significant disease at coronary angiography suggests the presence of a premature atherosclerotic process. ApoE polymorphism (presence of epsilon4 allele) appears to be a strong independent predictor of adverse events, suggesting a remarkable influence in the accelerated coronary disease.

Effect of the apolipoprotein E epsilon4 allele on white matter hyperintensities in dementia

BACKGROUND AND PURPOSE

The clinical significance of the apoE epsilon4 allele in white matter changes in patients with dementia has been a subject of debate. We studied the association between the apoE epsilon4 allele and white matter hyperintensities (WMHs) before and after control for (1) potential vascular risk factors and (2) the presence of lacunar infarcts in patients with dementia.

METHODS

The subjects were 131 patients with dementia who had either Alzheimer's disease or vascular dementia, or a combination of these 2 types of dementia, with or without WMHs, lacunar infarcts, or both. The association of the epsilon4 allele with WMHs was examined before and after control for age, sex, duration of symptoms, education level, severity of dementia, presence of lacunar infarcts, and potential vascular risk factors, including hypertension, diabetes mellitus, lipid disorders, smoking habit, drinking habit, and cardiac diseases.

RESULTS

WMHs were observed in 73 (55.7%) of the patients. Neither the number of apoE epsilon4 alleles nor their presence was significantly associated with WMHs before or after control for the potential confounding factors. Multiple logistic regression analyses revealed that age, the presence of hypertension, and the presence of lacunar infarcts were independently associated with WMHs.

CONCLUSIONS

The apoE epsilon4 allele was not associated with WMHs in patients with dementia. The fact that WMHs were significantly associated with hypertension and lacunar infarcts may indicate an ischemic origin of WMHs.

Apolipoprotein E and apolipoprotein D expression in a murine model of singlet oxygen-induced cerebral stroke

Apolipoprotein E (apoE)-deficient mice exhibit neuronal abnormalities similar to those in Alzheimer's disease and enhanced sensitivity to stroke-associated injuries. Here, we show that apoE deficiency results in impaired microglia/macrophage recruitment and accumulation after cerebral infarct. Astrogliosis and apolipoprotein D (apoD) expression are unaffected, suggesting that the neurological abnormalities of apoE-deficient mice could be due to impaired microglia/macrophage recruitment/accumulation, which is important for the clearance of neurodegenerative products via reverse cholesterol transport. To our knowledge, the results presented herein provide the first experimental evidence that brain microglia/macrophage recruitment/accumulation is affected by apoE deficiency. The insights gained from this study should facilitate the elucidation of the role of apoE in neurological disorders such as dementia with stroke and Alzheimer's disease.

Association of apolipoprotein (Apo)E genotype with plasma apo E levels

The purpose of this study was to investigate the effects of apolipoprotein (apo) E genotype on plasma apo E levels as well as serum total, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, and glucose values in 734 middle-aged and elderly, female and male subjects. Apo E allele frequencies were similar to those reported in other Caucasian populations. After adjustment for medications, alcohol use, smoking, age, and body mass index, apo E genotype was noted to have significant effects on apo E, total cholesterol, LDL cholesterol, and glucose levels in females, and on apo E, LDL cholesterol, and HDL cholesterol levels, as well as the total cholesterol (TC)/HDL cholesterol ratio in males. Female and male subjects with the apo E4 allele had significantly (P<0.05) lower plasma apo E (25 and 15%) and higher LDL cholesterol levels (5 and 2%), while those with the apo E2 allele had significantly (P<0.05) higher apo E (32 and 27%) and lower LDL cholesterol levels (10 and 10%) than the apo E3/3 group. Moreover, female apo E4 carriers had significantly (P<0.05) lower glucose values (11%) than the apo E3/3 group. These data are consistent with the concept that, in addition to the well known effects of apo E genotype on LDL-C values, this locus plays a very significant role in modulating plasma apo E levels.

Apolipoprotein E genotype and the risk of gallbladder disease in pregnancy

The E4 allele of apolipoprotein E (apoE4) has previously been associated with symptomatic gallstone disease. The aim of this study was to determine if apoE4 is associated with the development of gallbladder sludge and/or stones during pregnancy. We conducted a nested case-control study based on an ongoing cohort study of gallbladder disease in pregnancy. Women in this study receive gallbladder ultrasounds in each trimester of pregnancy. Cases (n = 52) were defined as women with incident gallbladder sludge or stones diagnosed at the third trimester ultrasound. Controls (n = 104) were defined as women without gallbladder sludge or stones on any of 3 study ultrasounds. ApoE genotyping was performed from stored white blood cell pellets. Data were analyzed by stratified analysis and multivariate logistic regression. Cases and controls were similar in baseline characteristics. Forty-two women had sludge, 6 had gallstones, and 4 had both sludge and stones. After adjusting for risk factors such as age, parity, and body mass index, the odds ratio (OR) for the association between heterozygosity or homozygosity for the apoE4 allele and incident gallbladder sludge or stones was 0.91 (95% confidence interval [CI], 0.41-2.02). Further adjustment for family medical history and serum lipid levels did not substantially change these results (OR, 0.73; 95% CI, 0.29-1.82). In conclusion, apoE4 appears to have little or no overall association with the development of new gallbladder sludge or stones in pregnancy. However, an effect could not be ruled out in certain subgroups, such as blacks or women who are homozygous for apoE4.

Age-dependent association of apolipoprotein E genotype with coronary and aortic atherosclerosis in middle-aged men: an autopsy study

BACKGROUND

Apolipoprotein E (apoE) polymorphism is one of the genetic determinants of serum cholesterol values. The apoE epsilon4 allele has been associated with advanced coronary heart disease (CHD) diagnosed by angiography, but the role of the apoE genotype in atherosclerosis has not been confirmed at vessel-wall level, nor is any age-dependent effect of the apoE genotype on the development of CHD known.

METHODS AND RESULTS

The right and left anterior descending coronary arteries (RCA and LAD) and the aorta from 700 male autopsy cases (Helsinki Sudden Death Study) in 1981-1982 and 1991-1992 (average age 53 years, range 33 to 70 years) were stained for fat, and all areas covered with fatty streaks, fibrotic plaques, and complicated lesions were measured. In the RCA and LAD, the apoE genotype was significantly associated with the area of total atherosclerotic lesions in men <53 years old but not with that in older men (P=0.0085 and P=0.041, respectively, for age-by-genotype interaction). Men <53 years old with the epsilon4/3 genotype showed 61% larger total atherosclerotic lesion area in the RCA (P=0.0027) and 26% larger area in the LAD (P=0.12) than did men with the epsilon3/3. The apoE epsilon4/3 was also associated with atherosclerotic lesions in the abdominal (P=0.014) and thoracic (P=0.12) aorta, but this effect, unlike that of the coronary arteries, was not age-related.

CONCLUSIONS

In men, the apoE epsilon4 allele is a significant genetic risk factor for coronary atherosclerosis in early middle age. This suggests that at older age, other known risk factors of CHD play a more important role in the atherosclerotic process than apoE polymorphisms.

Serum zinc, copper, insulin and lipids in Alzheimer's disease epsilon 4 apolipoprotein E allele carriers

BACKGROUND

Copper (Cu) and zinc (Zn) have been implicated in the development of Alzheimer's disease (AD) and, in this regard, Cu and Zn serum concentrations have been analysed but with inconclusive results. Serum insulin, glucose and cholesterol concentrations have been related to the apolipoprotein E genotype in non-AD populations.

DESIGN

In this study, we have analysed the relationship between serum Cu, Zn, insulin, glucose and lipid parameters (cholesterol, triglycerides, apoA and apoB apolipoproteins) in AD and AD epsilon 4 apolipoprotein E carriers by multivariate analysis using logistic regression, including the variables that showed a significance of P < 0.05 in the bivariate analysis.

RESULTS

The results obtained show that epsilon 4 apoE allele is an independent AD risk factor (OR = 6. 67, 95% CI = 2.59-17.16). In AD epsilon 4 apoE allele carriers, we found significantly higher Zn, Cu and insulin serum concentrations. Non-demented control subjects with at least one epsilon 4 apoE allele had the lowest serum insulin concentrations. There was no significant association between epsilon 4 apolipoprotein E allele and lipid parameters in the sample studied.

CONCLUSIONS

In AD we have found a significant association between higher serum Zn, Cu and insulin concentrations and the presence of an epsilon 4 apoE allele, but only greater serum Zn concentration appears to be an independent risk factor associated with the development of AD.

Relation of genetic polymorphisms of apolipoprotein E, angiotensin converting enzyme, apolipoprotein B-100, and glycoprotein IIIa and early-onset coronary heart disease

OBJECTIVE

Apolipoprotein E (APOE) E4, apolipoprotein B-100 (APOB) Q3611 allele, the angiotensin converting enzyme (ACE) deletion (D) allele and glycoprotein IIIa (GP3A) P33 mutant allele are reported to predispose to early-onset coronary heart disease (CHD). These associations were not all confirmed in more recent studies. To determine the impact of these alleles on CHD, we examined the prevalence of these mutations in patients presenting with early-onset CHD and compared them to those manifesting CHD later in life. The delayed-onset was considered a sign of longevity and would serve as a comparative group to assess prevalence of the biochemical and genetic risk factors.

METHODS

300 patients with a history of myocardial infarction or angina pectoris and angiographically documented CHD were studied. Patients were divided into two groups: group 1 (G1 = 150 patients) presenting with these findings under the age of 50 years; while group 2 (G2 = 150 patients) were patients presenting for the first time over the age of 65 years. Prevalence of the alleles of APOE, APOB, ACE and GP3A was assessed by molecular analysis. An association of any of these genotypes with early onset CHD could lead to a higher prevalence in the younger age group.

RESULTS AND CONCLUSIONS

None of the suspected alleles namely APOB Q3611 [G1: 10.7% vs. G2: 9.0%, p = 0.57], ACE D (G1: 52.0% vs. G2: 49.7%, p = 0.57), or the GP3A P33 (G1: 17.3% vs. G2: 15.7%; p = 0.58) showed any significant difference between the two groups. Subjects with APOE E4 were more frequent in the younger age group (G1: 18.3% vs. G2: 13.7%; p = 0.047), while APOE E2 was more frequent in G2 (G2: 10.0% vs. G1: 2.7%; p = 0.0002). Multivariate analysis showed an odds ratio of APOE E2 allele in G1 of 0.27 with a confidence interval of 0.10-0.73.

The relationship between risk factor levels and presence of coronary artery calcification is dependent on apolipoprotein E genotype

An important research question in the study of the genetics of coronary artery disease (CAD) is whether information about genetic variation will improve our ability to predict CAD beyond established risk factors. This question is especially relevant to the goal of identifying young, asymptomatic adults with coronary atherosclerosis who would benefit most from interventions to reduce risk. Coronary artery calcification (CAC) detected by electron-beam computed tomography is a relatively new method for detecting coronary atherosclerosis in asymptomatic individuals that has been shown to be a more accurate indicator of coronary atherosclerosis in asymptomatic individuals than other noninvasive techniques. In a study of asymptomatic women (n=169) and men (n=160) between the ages of 20 and 59 representative of the Rochester, Minnesota population, we used logistic regression to ask whether the most common Apolipoprotein (Apo) E genotypes (epsilon3/2, epsilon3/3, and epsilon4/3) predict the presence of CAC. The addition of information about ApoE genotypes to logistic models containing each separate risk factor did not improve prediction of CAC (P>0.10 in both women and men). However, there was significant evidence (P<0.10) that associations between variation in the probability of having CAC and variation in body mass index, plasma total cholesterol, and plasma ApoB in men and body mass index, plasma triglycerides, plasma ApoA1, and plasma ApoE in women were dependent on ApoE genotype. Thus, variation in the gene coding for ApoE may play a role in determining the contribution of established risk factors to risk of CAC.

The relationship between apolipoprotein E, dementia, and vascular illness

The purpose of this study was to concurrently assess the relationship of Apolipoprotein E (APOE) with both dementias and vascular illnesses in the very old. Nine hundred and fifty nine subjects (mean age 85 years) in a long-term care facility were genotyped and cognitively tested with the Mini Mental State Exam. All subjects were studied for the relationship of APOE with atherosclerotic heart disease, hypertension, or stroke without concomitant dementia. Four hundred fifty individuals met criteria for inclusion into one of the following groups: Alzheimer's disease (n = 318), vascular dementia (n = 49), or not demented controls (n = 83) and were investigated for the relationship between APOE and these diagnostic categories. APOE epsilon4 was not associated with atherosclerotic heart disease, hypertension, or stroke without concomitant dementia. The APOE epsilon3 allele was more common in men with atherosclerotic heart disease. In contrast, the APOE epsilon4 allele was more common in patients with Alzheimer's disease (22%) and vascular dementia (26%) than in not demented controls (7%). APOE epsilon4 is associated with dementias in the very old, whereas its relationship with either peripheral or central nervous system vascular disease without dementia is not as robust.

Apolipoprotein E2 reduces the low density lipoprotein level in transgenic mice by impairing lipoprotein lipase-mediated lipolysis of triglyceride-rich lipoproteins

Apolipoprotein (apo) E2 is often associated with low levels of low density lipoprotein (LDL) cholesterol and high levels of plasma triglycerides in humans. Mice expressing apoE2 also have low LDL levels. To evaluate the possible role of the LDL receptor in the cholesterol-lowering effect of apoE2, we bred transgenic mice expressing low levels of apoE2 with LDL receptor-null mice (hE2(+/0), LDLR-/-). Even in the absence of the LDL receptor, plasma total and LDL cholesterol levels decreased progressively with increasing levels of plasma apoE2. At plasma apoE2 levels >20 mg/dl, LDL cholesterol was approximately 45% lower than in LDLR-/- mice. Thus, the LDL cholesterol-lowering effect of apoE2 is independent of the LDL receptor. In contrast, plasma triglyceride levels increased (mostly in very low density lipoproteins (VLDL) and intermediate density lipoproteins (IDL)) progressively as apoE2 levels increased. At plasma apoE2 levels >20 mg/dl, triglycerides were approximately 150% higher than in LDLR-/- mice. Furthermore, in apoE-null mice (hE2(+/0), mE-/-), apoE2 levels also correlated positively with plasma triglyceride levels, suggesting impaired lipolysis in both hE2(+/0),LDLR-/- and hE2(+/0),mE-/- mice. Incubating VLDL or IDL from the hE2(+/0),LDLR-/- or the hE2(+/0),mE-/- mice with mouse postheparin plasma inhibited lipoprotein lipase-mediated lipolysis of apoE2-containing VLDL and IDL by approximately 80 and approximately 70%, respectively, versus normal VLDL and IDL. This observation was confirmed by studies with triglyceride-rich emulsion particles, apoE2, and purified lipoprotein lipase. Furthermore, apoE2-containing VLDL had much less apoC-II than normal VLDL. Adding apoC-II to the incubation partially corrected the apoE2-impaired lipolysis in apoE2-containing VLDL or IDL and corrected it completely in apoE2-containing emulsion particles. Thus, apoE2 lowers LDL cholesterol by impairing lipoprotein lipase-mediated lipolysis of triglyceride-rich lipoproteins (mostly by displacing or masking apoC-II). Furthermore, the effects of apoE2 on both plasma cholesterol and triglyceride levels are dose dependent and act via different mechanisms. The increase in plasma cholesterol caused by apoE2 is due mostly to impaired clearance, whereas the increase in plasma triglycerides is caused mainly by apoE2-impaired lipolysis of triglyceride-rich lipoproteins.

Exercise-induced silent myocardial ischemia in master athletes

High-physical activity levels are associated with reduced risk of symptomatic coronary artery disease (CAD). However, there are a number of reports of exercise-related sudden death and myocardial infarction in aerobically trained athletes. This study compared the prevalence of exercise-induced silent myocardial ischemia on maximum graded exercise tests with tomographic thallium scintigraphy in 70 master male athletes (63 +/- 6 years, mean +/- SD) (maximum aerobic capacity, VO2max >40 ml/kg/min) and in 85 healthy untrained men (61 +/- 7 years) with no history of CAD. The prevalence of silent ischemia (exercise-induced ST-segment depression on electrocardiogram and perfusion abnormalities on thallium scintigraphy) was similar in athletes and untrained men; 16% of the athletes (11 of 70) had silent ischemia compared with 21% of the untrained men (chi-square = 0.81, p = 0.36). No athletes had hyperlipidemia, systemic hypertension, or diabetes mellitus. However, the apolipoprotein E4 allele was present in 9 of the 11 athletes with silent ischemia compared with 2 of 32 athletes with normal exercise tests (chi-square = 24, p = 0.0001). These results suggest that older male athletes with the apolipoprotein E4 allele are at increased risk for the development of exercise-induced silent ischemia.

Increased J774 macrophage cytotoxicity of late postprandial triglyceride-rich lipoproteins from normolipidemic young men expressing an apolipoprotein epsilon 4 allele

It has been demonstrated that normolipidemic young men with apolipoprotein E4/3 phenotype have a prolonged postprandial clearance of triglyceride-rich lipoproteins following a high-fat diet. In the present study, we isolated fasting and postprandial (3 and 8 h) lipoprotein fraction from normolipidemic young men with E3/3 and E4/3 phenotypes and examined the in vitro cytotoxicity of these lipoproteins towards J774 macrophages. 8 h E4/3 very low density lipoprotein (VLDL) were significantly more cytotoxic than either 8 h E3/3 VLDL or fasting and 3 h E4/3 VLDL (lactate dehydrogenase (LDH) released: 161 +/- 21, 107 +/- 9, 88 +/- 16 and 101 +/- 12 I.U./l, respectively). Fasting E4/3 intermediate density lipoprotein (IDL) were also significantly more cytotoxic than either fasting E3/3 IDL or 3 h and 8 h E4/3 IDL (LDH released: 105 +/- 23, 60 +/- 9, 37 +/- 5 and 53 +/- 16 I.U./l, respectively), whereas either fasting or postprandial low density lipoprotein (LDL) and high density lipoprotein (HDL) samples did not show any difference in cytotoxicity between the two groups studied. 8 h E4/3 VLDL samples incubated with J774 macrophages had a lower esterified cholesterol (40 +/- 3 versus 52 +/- 3 micrograms), and higher triglyceride (783 +/- 133 versus 418 +/- 64 micrograms) and free fatty acid (FFA) (2.0 +/- 0.4 versus 0.9 +/- 0.1 microgram) content than fasting E4/3 VLDL. The increased macrophage cytotoxicity of late postprandial triglyceride-rich lipoproteins seems to be related to the FFA content of E4/3 VLDL.

Genetic predictors of common disease: apolipoprotein E genotype as a paradigm

PURPOSE

Genetic variation of a common genetic polymorphism at the structural locus for apolipoprotein E (apoE) has been associated with risk of elevated serum lipids, coronary artery disease, and Alzheimer disease, all of which are multifactoral disorders and are inherited in a complex fashion. Although the apoE polymorphism is only one risk factor in a complex pattern of inheritance, it gives us a foothold into the understanding of the genetic architecture of these disorders. However, apoE also exemplifies the complications that can arise in the use of genetic markers to predict disease. This paper considers the study of apolipoprotein E genotype effects as an example of the following analytical complications: changes in allele frequencies and allele effects with age, pleiotrophic effects of genetic loci, the existence of more than one alternative allele at a locus, and the expectation of a variety of interactions.

METHODS

Publications that exemplify these complications are cited and discussed. No original analyses are presented.

RESULTS

There is evidence that the relative frequency of the apoE epsilon4 allele declines with age after the sixth decade of life and that the effects of the APOE allele on lipids also may be age-dependent. Grouping of genotypes may not accurately characterize the effects of individual genotypes. Interactions between APOE genotype and a number of factors, including family history of dementia, are demonstrated for the effects of APOE in Alzheimer disease as well as for the effects of apoE on serum lipids.

CONCLUSION

Careful attention must be paid to these and other analytical issues when genotype is a predictor.