Apolipoprotein E polymorphism in American Indians and its relation to plasma lipoproteins and diabetes. The Strong Heart Study

2024 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including prevalence and incidence, mortality and morbidity, use and costs of care and the ramifications of AD for family caregivers, the dementia workforce and society. The Special Report discusses the larger health care system for older adults with cognitive issues, focusing on the role of caregivers and non-physician health care professionals. An estimated 6.9 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060, barring the development of medical breakthroughs to prevent or cure AD. Official AD death certificates recorded 119,399 deaths from AD in 2021. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death in the United States. Official counts for more recent years are still being compiled. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2021, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 140%. More than 11 million family members and other unpaid caregivers provided an estimated 18.4 billion hours of care to people with Alzheimer's or other dementias in 2023. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $346.6 billion in 2023. Its costs, however, extend to unpaid caregivers' increased risk for emotional distress and negative mental and physical health outcomes. Members of the paid health care and broader community-based workforce are involved in diagnosing, treating and caring for people with dementia. However, the United States faces growing shortages across different segments of the dementia care workforce due to a combination of factors, including the absolute increase in the number of people living with dementia. Therefore, targeted programs and care delivery models will be needed to attract, better train and effectively deploy health care and community-based workers to provide dementia care. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2024 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $360 billion. The Special Report investigates how caregivers of older adults with cognitive issues interact with the health care system and examines the role non-physician health care professionals play in facilitating clinical care and access to community-based services and supports. It includes surveys of caregivers and health care workers, focusing on their experiences, challenges, awareness and perceptions of dementia care navigation.

Plasma biomarkers of Alzheimer's disease and related dementias in American Indians: The Strong Heart Study

INTRODUCTION

Identification of Alzheimer's disease (AD) needs inexpensive, noninvasive biomarkers, with validation in all populations.

METHODS

We collected plasma markers in older American Indian individuals: phosphorylated-tau181 (pTau181); amyloid-beta (Aβ) 40,42; glial fibrillary acidic protein (GFAP); and neurofilament light chain (NfL). Plasma markers were analyzed for discriminant properties with cognitive status and etiology using receiver operating characteristic (ROC) analysis.

RESULTS

PTau181, GFAP, NfL plasma values were significantly associated with cognition, but Aβ were not. Discriminant performance was moderate for individual markers, with pTau181, GFAP, NfL performing best, but an empirically selected panel of markers (age, sex, education, pTau181, GFAP, NfL, Aβ4240 ratio) had excellent discriminant performance (AUC > 0.8).

DISCUSSION

In American Indian individuals, pTau181 and Aβ values suggested more common pathology than in majority populations. Aβ was less informative than in other populations; however, all four markers were needed for a best-performing dementia diagnostic model. These data validate utility of AD plasma markers, while suggesting population-specific diagnostic characteristics.

2023 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease, including prevalence and incidence, mortality and morbidity, use and costs of care, and the overall impact on family caregivers, the dementia workforce and society. The Special Report examines the patient journey from awareness of cognitive changes to potential treatment with drugs that change the underlying biology of Alzheimer's. An estimated 6.7 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, and Alzheimer's disease was officially listed as the sixth-leading cause of death in the United States. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. This trajectory of deaths from AD was likely exacerbated by the COVID-19 pandemic in 2020 and 2021. More than 11 million family members and other unpaid caregivers provided an estimated 18 billion hours of care to people with Alzheimer's or other dementias in 2022. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $339.5 billion in 2022. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Members of the paid health care workforce are involved in diagnosing, treating and caring for people with dementia. In recent years, however, a shortage of such workers has developed in the United States. This shortage - brought about, in part, by COVID-19 - has occurred at a time when more members of the dementia care workforce are needed. Therefore, programs will be needed to attract workers and better train health care teams. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2023 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $345 billion. The Special Report examines whether there will be sufficient numbers of physician specialists to provide Alzheimer's care and treatment now that two drugs are available that change the underlying biology of Alzheimer's disease.

APOE genotype, hippocampus, and cognitive markers of Alzheimer's disease in American Indians: Data from the Strong Heart Study

BACKGROUND

The apolipoprotein E (APOE) ε4 allele confers higher risk of neurodegeneration and Alzheimer's disease (AD), but differs by race/ethnicity. We examined this association in American Indians.

METHODS

The Strong Heart Study is a population-based cohort of American Indians who were 64 to 95 years of age in 2010 to 2013. APOE ε4 status, brain imaging, and neuropsychological testing was collected in N = 811 individuals. Summary statistics, graphics, and generalized linear regressions-adjusted for sociodemographics, clinical features, and intracranial volume with bootstrap variance estimator-compared APOE ε4 carriers with non-carriers.

RESULTS

APOE ε4 carriers comprised 22% of the population (0.7% homozygotes). Participants were mean 73 years, 67% female, and 54% had some college education. The majority were obese (>50%), hypertensive (>80%), and diabetic (>50%). Neither imaging findings nor multidomain cognitive testing showed any substantive differences between APOE ε4 carriers and non-carriers.

CONCLUSION

We found no evidence of neurodegenerative risk from APOE ε4 in American Indians. Additional studies are needed to examine potential protective features.

Roles of Nutraceuticals and Functional Food in Prevention of Cardiovascular Disease

The chapter provides an overview of cardiovascular disease, a major cause of mortality worldwide. It relates economic and social impacts to the disease, especially in developing countries. One of the approaches to addressing this challenge is increasing awareness within society, through implementation of education programs. It is important for society to understand the types and roles of the risk factors leading to cardiovascular disease. Emphasis is on the role of functional food and nutraceuticals as dietary sources that could prevent development of cardiovascular disease. The chapter highlights roles of nutraceuticals and functional food sources from medical plants, seeds, berries, and tropical fruits in lowering risk factors. Key findings from trials conducted in Asia, China, Europe, and America provide supporting evidence for the importance of functional food to health, and its potential for modifying the level of risk factors related to cardiovascular diseases.

Apolipoprotein E Genotype, Meat, Fish, and Egg Intake in Relation to Mortality Among Older Adults: A Longitudinal Analysis in China

Introduction: The interactions between apolipoprotein E (APOE) genotype and diet pattern changes were found significant in several trials, implying that APOE gene may modify the effect of animal protein-rich food on health outcomes. We aim to study the interaction of APOE genotype with the effect of meat, fish and egg intake on mortality.

Methods: This population-based study enrolled 8,506 older adults (mean age: 81.7 years, 52.3% female) from the Chinese Longitudinal Healthy Longevity Study. The intake frequency of meat, fish and egg was assessed by 3-point questions at baseline. Cox regression was conducted to calculate the hazard ratios for all-cause mortality of intake levels of meat, fish and egg. The analyses were stratified by APOE genotype and sex. The analyses were performed in 2020.

Results: In the multivariable-adjusted models, meat and fish intake was associated with all-cause mortality (high vs. low intake: meat: HR: 1.14, 95% CI: 1.01, 1.28; fish: HR: 0.83, 95% CI: 0.73, 0.95). APOE genotype have significant interactions with meat and fish intake (Ps < 0.05). Compared with low fish intake, high fish intake was associated with lower risk of mortality (HR: 0.74, 95% CI: 0.56–0.98) only among the APOE ε4 carriers. High meat intake was significantly associated with higher risks of mortality (HR: 1.13, 95% CI: 1.04–1.25) only among the APOE ε4 non-carriers. The interactive relationship was restricted among the male. No significant findings were observed between egg and mortality among carriers or non-carriers.

Conclusions: Among Chinese older adults, the significance of associations of mortality with reported meat or fish intake depended on APOE-E4 carriage status. If validated by other studies, our findings provide evidence for gene-based “precision” lifestyle recommendations.

Interaction between APOE ε4 and dietary protein intake on cognitive decline: A longitudinal cohort study

OBJECTIVE

To exam the association of cognitive decline with APOE ε4 allele carriage and dietary protein intake and investigate whether there is a gene-diet (GxD) interaction of APOE ε4 allele carriage and dietary protein intake on cognitive decline in a nationwide cohort of older adults.

METHODS

A cohort study of participants from Chinese Longitudinal Healthy Longevity Survey was conducted from 2008 to 2014. A total of 3029 participants (mean age of 77.0 years, SD = 9.0; 49.3% were women) was enrolled. We genotyped APOE ε4 allele for each participant and calculated the diversity of dietary protein intake (DDPI) by summing up the frequency of intake of the 6 protein-rich foods (meats, fish, eggs, nuts, dairy products, and bean products). We assessed cognitive function using the Mini-Mental State Examination (MMSE). We used ordinal regression model to estimate the independent and joint effects of APOE ε4 carrier and dietary protein intake on cognitive decline, adjusting for potential confounders of age, sex, education, socio-economic status, lifestyles, BMI, and cardiometabolic conditions.

RESULTS

There was significant association between carrying APOE ε4 allele and faster cognitive decline (Odds ratio: 1.19, 95% CI = 1.00-1.42), independent of potential confounders. While the associations of DDPI and the intake of 6 protein-rich foods with cognitive decline did not reach any statistical significance. We observed significant interactions of APOE ε4 with DDPI and fish intake, at multiple correction-adjusted Ps < 0.05. In those who were APOE ε4 carriers rather than non-carriers, both high DDPI (OR = 0.54, 95% CI: 0.34-0.88) and daily fish intake (OR = 0.43, 95% CI: 0.22-0.78) were significantly associated with slower cognitive decline, respectively. We also found that frequent intake of fish benefits women more than men regarding the mitigating of cognitive decline among APOE ε4 allele carriers (P for interaction = 0.016).

CONCLUSIONS

The results of this study support the hypothesis that diversified protein food intake in addition to frequent fish intake may reduce the detrimental effect of APOE ε4 on cognitive health.

Cardiovascular Health in American Indians and Alaska Natives: A Scientific Statement From the American Heart Association

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death among American Indians and Alaska Natives. Over the past 50 years, the prevalence of CVD has been rising among American Indians and Alaska Natives. The objective of this statement is to summarize population-level risk factors and management techniques tailored for the American Indian and Alaska Native populations.

METHODS

PubMed/MEDLINE, the Centers for Disease Control and Prevention, and the annual Heart Disease and Stroke Statistics report from the American Heart Association were used to identify risk factors and interventions specific to American Indians and Alaska Natives.

RESULTS

Diabetes mellitus is a major contributor to disproportionately higher rates of coronary heart disease among American Indians and Alaska Natives compared with other racial and ethnic groups. Additional risk factors for CVD include low-density lipoprotein cholesterol levels, hypertension, renal disease, age, and sex. Smoking and exposure to toxic metals are risk factors for some subpopulations. A quarter of American Indians live below the federal poverty line, and thus, low socioeconomic status is an important social determinant of cardiovascular health. Community-based interventions have reduced CVD risk in American Indians and Alaska Natives. Underreporting of American Indian and Alaska Native race could underestimate the extent of CVD in this population.

CONCLUSIONS

Prevention and treatment of CVD in American Indians and Alaska Natives should focus on control of risk factors and community-based interventions that address social determinants of health, particularly among individuals with diabetes mellitus. Accurate reporting of race/ethnicity is encouraged to address race-specific risk factors.

Beyond the CNS: The many peripheral roles of APOE

Apolipoprotein E (APOE) is a multifunctional protein synthesized and secreted by multiple mammalian tissues. Although hepatocytes contribute about 75% of the peripheral pool, APOE can also be expressed in adipose tissue, the kidney, and the adrenal glands, among other tissues. High levels of APOE production also occur in the brain, where it is primarily synthesized by glia, and peripheral and brain APOE pools are thought to be distinct. In humans, APOE is polymorphic, with three major alleles (ε2, ε3, and ε4). These allelic forms dramatically alter APOE structure and function. Historically, the vast majority of research on APOE has centered on the important role it plays in modulating risk for cardiovascular disease and Alzheimer's disease. However, the established effects of this pleiotropic protein extend well beyond these two critical health challenges, with demonstrated roles across a wide spectrum of biological conditions, including adipose tissue function and obesity, metabolic syndrome and diabetes, fertility and longevity, and immune function. While the spectrum of biological systems in which APOE plays a role seems implausibly wide at first glance, there are some potential unifying mechanisms that could tie these seemingly disparate disorders together. In the current review, we aim to concisely summarize a wide breadth of APOE-associated pathologies and to analyze the influence of APOE in the development of several distinct disorders in order to provide insight into potential shared mechanisms implied in these various pathophysiological processes.

Obstructive sleep apnea and hypertriglyceridaemia share common genetic background: Results of a twin study

Obstructive sleep apnea is associated with an increased risk of hypertension, diabetes and dyslipidaemia. Both obstructive sleep apnea and its comorbidities are at least partly heritable, suggesting a common genetic background. Our aim was to analyse the heritability of the relationship between obstructive sleep apnea and its comorbidities using a twin study. Forty-seven monozygotic and 22 dizygotic adult twin pairs recruited from the Hungarian Twin Registry (mean age 51 ± 15 years) attended an overnight diagnostic sleep study. A medical history was taken, blood pressure was measured, and blood samples were taken for fasting glucose, total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and lipoprotein (a). To evaluate the heritability of obstructive sleep apnea and its comorbidities bivariate analysis was performed with an adjustment for age, gender, body mass index (BMI) and smoking after false discovery rate correction and following exclusion of patients on lipid-lowering and antidiabetic medications. There was a significant correlation between indices of obstructive sleep apnea severity, such as the apnea-hypopnea index, oxygen desaturation index and percentage of sleep time spent with oxygen saturation below 90%, as well as blood pressure, serum triglyceride, lipoprotein (a) and glucose levels (all p < .05). The bivariate analysis revealed a common genetic background for the correlations between serum triglyceride and the oxygen desaturation index (r = .63, p = .03), as well as percentage of sleep time spent with oxygen saturation below 90% (r = .58, p = .03). None of the other correlations were significantly genetically or environmentally determined. This twin study demonstrates that the co-occurrence of obstructive sleep apnea with hypertriglyceridaemia has a genetic influence and heritable factors play an important role in the pathogenesis of dyslipidaemia in obstructive sleep apnea.

Roles of Nutraceuticals and Functional Food in Prevention of Cardiovascular Disease

The chapter provides an overview of cardiovascular disease, a major cause of mortality worldwide. It relates economic and social impacts to the disease, especially in developing countries. One of the approaches to addressing this challenge is increasing awareness within society, through implementation of education programs. It is important for society to understand the types and roles of the risk factors leading to cardiovascular disease. Emphasis is on the role of functional food and nutraceuticals as dietary sources that could prevent development of cardiovascular disease. The chapter highlights roles of nutraceuticals and functional food sources from medical plants, seeds, berries, and tropical fruits in lowering risk factors. Key findings from trials conducted in Asia, China, Europe, and America provide supporting evidence for the importance of functional food to health, and its potential for modifying the level of risk factors related to cardiovascular diseases.

Left Ventricular Mass, Brain Magnetic Resonance Imaging, and Cognitive Performance: Results From the Strong Heart Study

Left ventricular mass (LVM) has been shown to serve as a measure of target organ damage resulting from chronic exposure to several risk factors. Data on the association of midlife LVM with later cognitive performance are sparse. We studied 721 adults (mean age 56 years at baseline) enrolled in the Strong Heart Study (SHS, 1993-1995) and the ancillary CDCAI (Cerebrovascular Disease and Its Consequences in American Indians) Study (2010-2013), a study population with high prevalence of cardiovascular disease. LVM was assessed with transthoracic echocardiography at baseline in 1993 to 1995. Cranial magnetic resonance imaging and cognitive testing were undertaken between 2010 and 2013. Generalized estimating equations were used to model associations between LVM and later imaging and cognition outcomes. The mean follow-up period was 17 years. A difference of 25 g in higher LVM was associated with marginally lower hippocampal volume (0.01%; 95% confidence interval, 0.02-0.00; P=0.001) and higher white matter grade (0.10; 95% confidence interval, 0.02-0.18; P=0.014). Functionally, participants with higher LVM tended to have slightly lower scores on the modified mini-mental state examination (0.58; 95% confidence interval, 1.08-0.08; P=0.024). The main results persisted after adjusting for blood pressure levels or vascular disease. The small overall effect sizes are partly explained by survival bias because of the high prevalence of cardiovascular disease in our population. Our findings emphasize the role of cardiovascular health in midlife as a target for the prevention of deleterious cognitive and functional outcomes in later life.

Fuzzy set analyses of genetic determinants of health and disability status

Analyses of complex genotype-phenotype relations require new statistical procedures because of the potentially high dimensionability of those relations which are expressed with both measurement error and stochasticity in the correlation function. We propose modifying a multivariate procedure called grade of membership (GoM) analysis to deal with the special problems of such analyses. In doing so, we make clear some special features of the GoM model for multivariate analysis of high dimensional, discrete data. This is illustrated for apolipoprotein E (APOE) assessments made on 1805 people in the 1999 National Long Term Care Survey. A number of interesting relations with APOE polymorphism were found where disability profiles were more predictive than specific diagnoses because they implicitly contained information on chronicity and severity of disease processes.

Apolipoprotein E Genotype and Sex Influence Glucose Tolerance in Older Adults: A Cross-Sectional Study

Background

Glucose intolerance and apolipoprotein ε4 allele (E4+) are risk factors for Alzheimer's disease (AD). Insulin sensitizers show promise for treating AD, but are less effective in E4+ individuals. Little is known about how the APOE genotype influences glucose metabolism.

Methods

Cross-sectional analysis of 319 older adults who underwent oral glucose tolerance tests; a subset had insulin, amyloid beta (Aβ₄₂), and Mini Mental Status Examination. Glucose and insulin patterns with respect to cognitive diagnosis, E4 status, and sex were examined with analysis of covariance and Pearson correlation.

Results

People with cognitive impairment had higher fasting insulin levels. E4 status did not affect fasting glucose values, whereas men had higher fasting glucose levels than women. E4+ men had the lowest and E4+ women had the highest glucose levels, compared to E4- groups; insulin did not differ by sex or E4 group. E4 status and sex moderated correlations between metabolic measures and AD risk factors including age and Aβ.

Conclusions

Insulin resistance was associated with cognitive impairment, and sex, E4 status, and glucose values are interrelated in older adults at risk of AD. Understanding glucose metabolism for different APOE and sex groups may help elucidate differences in therapeutic responses.

Combined PCSK9 and APOE polymorphisms are genetic risk factors associated with elevated plasma lipid levels in a Thai population

Proprotein convertase subtilisin/kexin type 9 (PCSK9) and apolipoprotein E (ApoE) play a key role in the regulation of lipid metabolism. We aimed to investigate the effects of PCSK9 (R46L, I474V, and E670G) and APOE polymorphisms on lipid levels in a Southern Thai population. A total of 495 participants (307 urban, 188 rural) were recruited for the study. Anthropometric and biochemical variables were evaluated. PCSK9 and APOE polymorphisms were analyzed using PCR-RFLP. The 46L urban male carriers had significantly higher diastolic blood pressure (DBP) and fasting blood sugar compared with non-carriers. In contrast, the 46L urban female carriers had significantly lower total cholesterol (TC) and LDL-C levels compared with non-carriers. The 474V rural female carriers had significantly lower HDL-C levels than non-carriers. The 670G urban female carriers showed significantly higher TC and LDL-C levels compared with non-carriers. APOE4 carriers had increased TC and LDL-C levels relative to APOE3 carriers in the urban males. APOE2 carriers had decreased TC and/or LDL-C levels compared with APOE3 carriers in urban males and females. A significant trend of increased TC and LDL-C levels was observed in non-APOE4-PCSK9 670EE carriers to APOE4-PCSK9 670EG carriers in urban subjects. In summary, R46L, I474V, and E670G may be genetic risk factors for cardiovascular disease (CVD) in urban males, rural females, and urban females, respectively. In contrast, R46L had a favorable lipid profiles that may protect against CVD in urban females. The combination of PCSK9 E670G and APOE polymorphisms may represent an independent factor for the determination of lipid levels.

Distribution and effect of apo E genotype on plasma lipid and apolipoprotein profiles in overweight/obese and nonobese Chinese subjects

BACKGROUND

Apolipoprotein E (apo E) polymorphism has been reported to influence some lipid profile abnormalities in some ethnic groups. This study was conducted mainly to examine the possible association of apo E polymorphism with overweight/obesity in a South West Chinese population.

METHODS

Four hundred and fifty-four Han Chinese (282 overweight/obese and 172 normal weight control subjects) in Chengdu area were studied using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

The genotype and allele frequencies of apo E polymorphism in cases of overweight/obesity showed no significant statistical difference compared to those of controls. In the control group, both apo E4 and E3 allele carriers had the higher serum LDL-C and lower triglycerides (TGs) and apo E concentrations than those with apo E2 carriers, while apo E2 allele carriers had higher serum apo C-II levels than apo E3 carriers (P < 0.05). In overweight/obese group, genotype-related low density Lipoprotein-Cholesterol (LDL-C) variations were also evident, with the changes being in a same direction as the effect in the controls, and apo B100 levels were decreased and apo E increased in apo E2 allele carriers when compared with respective apo E4 and apo E4/apo E3 allele carriers (all P < 0.05).

CONCLUSION

Polymorphism of the apo E gene is associated with altered plasma LDL-C and TG, as well as apo B, apo C-II, and apo E concentrations. The effects on TG, apo B, and apo C-II levels are BMI dependent in Chinese population of Chengdu area.

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.

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.

APOEpolymorphism distribution among Native Americans and related populations

BACKGROUND

Apolipoprotein E (apoE, protein; APOE, gene) plays a central role in lipid metabolism. Three common alleles, E*2, E*3 and E*4 have quantitative effects on lipid and lipoproteins levels, which are major risk determinants of cardiovascular diseases in several populations. Given their clinical significance, it is of interest to know the distribution of APOE variants in populations from diverse ethnic groups, as well as to determine if this polymorphism presents variations that might be associated with given evolutionary factors.

AIM

We report the distribution of APOE polymorphisms in Native American populations from South America, comparing it with other native populations of the Americas and Siberia.

SUBJECTS AND METHODS

The sample consisted of 315 individuals from nine Native American populations living at subtropical latitudes of Argentina, Brazil and Paraguay. The extended analysis included 50 populations across South and North America, Greenland and Siberia. The geographic patterns of the variation were investigated through correlation analysis, spatial autocorrelation and analysis molecular of variance (AMOVA).

RESULTS

The incidence of the most common allele (APOE*3) in the sample analysed ranged from 0.78 to 0.98. The second allele in prevalence, APOE*4, varied from 0.00 to 0.17. The rare allele APOE*2 was found in five of the nine populations investigated. This variant was found in a male with both maternal and paternal Native American lineages, suggesting that this allele is present in Native Americans and hence should not be used as an indicator of admixture. APOE*3 and APOE*4 present, respectively, positive and negative associations with latitude, although the pattern is much more pronounced in the Northern Hemisphere than in South America. APOE*2 increases its frequency with latitude but this pattern is statistically significant only in South America.

CONCLUSION

The overall APOE spatial pattern seems, in general, compatible with a directional demographic expansion which occurred in north-eastern Asia and much of the New World. The APOE*2 allele shows this pattern in South America but a random distribution in the Northern Hemisphere, suggesting that the possibility of selection should not be discarded.

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.

Association between apolipoprotein E polymorphism, lipids, and coronary artery disease in Tunisian type 2 diabetes

BACKGROUND

The relationship between apolipoprotein E (ApoE) polymorphism, fasting lipid parameters, and coronary artery disease (CAD) is controversial.

METHODS

We studied this relationship, for the first time, in Tunisian type 2 diabetic patients. The studied population comprised 157 type 2 diabetic patients (145 of them were not on any lipid-lowering drugs). Fasting lipids were measured by enzymatic methods and ApoE genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Our results showed that the alleles E2, E3, and E4 were found in 4%, 88%, and 8% of patients, respectively. In the total type 2 diabetic population, no association was found between ApoE polymorphism, lipid parameters, and CAD. However, the E4 allele was associated with elevated low-density lipoprotein cholesterol concentration and with CAD in type 2 diabetic men.

CONCLUSION

The effect of ApoE polymorphism on CAD is gender-dependent in the Tunisian type 2 diabetic population. ApoE 4 allele may enhance atherogenesis indirectly by a strong effect on low-density lipoprotein cholesterol.

Sex-specific interaction between APOE genotype and carbohydrate intake affects plasma HDL-C levels: the Strong Heart Family Study

Low plasma levels of high-density lipoprotein cholesterol (HDL-C) are identified as a risk factor for cardiovascular disease (CVD). Sexual dimorphism, however, is widely reported in both HDL-C and CVD, with the underlying explanations of these sexual differences not fully understood. HDL-C is a complex trait influenced by both genes and dietary factors. Here we examine evidence for a sex-specific effect of APOE and the macronutrient carbohydrate on HDL-C, triglycerides (TG) and apoprotein A-1 (ApoA-1) in a sample of 326 male and 423 female participants of the Strong Heart Family Study (SHFS). Using general estimating equations in SAS to account for kinship correlations, stratifying by sex, and adjusting for age, body mass index (BMI) and SHS center, we examine the relationship between APOE genotype and carbohydrate intake on circulating levels of HDL-C, TG, and ApoA-1 through a series of carbohydrate-by-sex interactions and stratified analyses. APOE-by-carbohydrate intake shows significant sex-specific effects. All males had similar decreases in HDL-C levels associated with increased carbohydrate intake. However, only those females with APOE-4 alleles showed significantly lower HDL-C levels as their percent of carbohydrate intake increased, while no association was noted between carbohydrate intake and HDL-C in those females without an APOE-4 allele. These findings demonstrate the importance of understanding sex differences in gene-by-nutrient interaction when examining the complex architecture of HDL-C variation.

Effects of ezetimibe on lipids and lipoproteins in patients with hypercholesterolemia and different apolipoprotein E genotypes

BACKGROUND

The epsilon4 allele of the gene encoding apolipoprotein E (apoE) is associated with elevated serum levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), as well as an increased risk of coronary heart disease (CHD), greater disease severity, and higher CHD mortality. ApoE epsilon4 allele carriers have also shown reduced lipid and lipoprotein responses to lipid-modifying pharmacotherapy and lifestyle modifications.

OBJECTIVE

To provide preliminary descriptive data on the effects of apoE genotype on lipid and lipoprotein responses to the cholesterol absorption inhibitor ezetimibe (Ezetrol/Zetia) in Hungarian subjects not at cholesterol goals at baseline.

METHODS

This prospective open-label study compared the effects of the cholesterol absorption inhibitor ezetimibe 10 mg/day for up to 6 weeks added to existing therapies on the lipid profiles of 14 epsilon4 allele carriers and 14 age- and gender-matched APOE3/APOE3 homozygotes.

RESULTS

Treatment with ezetimibe reduced TC, LDL-, and triglycerides, and increased high-density lipoprotein cholesterol (HDL-) significantly from baseline, and to similar extents, in both groups, lowering TC from baseline by 13.7% in APOE3/APOE3 homozygotes compared with 12.1% in epsilon4 allele carriers (p = 0.139); LDL-C by 22.8% (vs. 19.6%; p = 0.081); and triglycerides by 9.2% (vs. 9.1%; p = 0.120). Ezetimibe also increased HDL-C by 8.0% in subjects with the epsilon3/epsilon3 genotype compared with 8.9% in epsilon4 allele carriers (p = 0.263).

CONCLUSIONS

Ezetimibe significantly improved lipid and lipoprotein profiles from baseline irrespective of apoE epsilon3/epsilon3 or epsilon4 genotype in Hungarian subjects not at cholesterol goals. Limitations of our study include its open-label nature and small sample population, as well as the facts that patients with the epsilon4 allele were not included and data were not collected on initial cholesterol levels, initial statin doses, cholesterol responses to statins, and the safety and tolerability of ezetimibe. Further randomized controlled studies in larger numbers of people followed for longer intervals are warranted to confirm these findings.

Apolipoprotein E polymorphism in Southern Iran: E4 allele in the lowest reported amounts

BACKGROUND

Apolipoprotein E (apoE) with three major alleles E2, E3 and E4 is one of the critical genes in lipid metabolism. Common apoE alleles are in association with an increase in risk for central nervous and cardiovascular diseases such as Alzheimer's disease, dementia, multiple sclerosis, atherosclerosis, coronary heart disease, hyperlipoproteinemia and stroke. ApoE3 is known as the most frequent allele in all populations, while association of apoE gene polymorphism with reported diseases have mostly been related to other two major alleles especially apoE4.

OBJECTIVE

To determine of apoE alleles frequencies in Southern Iran and comparison of those frequencies with other populations.

METHODS

DNA was extracted from the whole blood of 198 healthy unrelated candidates from population of Fars Province, Southern Iran, for apoE genotyping who were checked up by a physician. The frequencies of apoE alleles were compared with other populations by chi(2) test.

RESULTS

The frequencies of E2, E3 and E4 were 0.063, 0.886 and 0.051 respectively. These values were similar to those reported from populations of Kuwait, Oman, Lebanon, India, Turkey, Greece, Spain, Sardinia Islands of Italy and two Iranian populations but were different from South of Italy and Caucasians in other Europe regions, American, American-Indian, African, East Asian and Saudi populations (P < 0.05).

CONCLUSION

The frequency of E4 allele as a genetic risk factor for some multifactorial diseases in the population of Southern Iran is in the lowest reported amounts in the world. Iranian population has Caucasoid origin but differs from some Caucasian populations in Europe and America. The results of present study are in agreement with the historical evidences which show admixture of Iranian population with other populations and some studies based on genetic polymorphisms in the population of Southern Iran.

Apo E gene polymorphism on development of diabetic nephropathy

Type 2 diabetes causes premature morbidity and mortality due to the complications of atherosclerosis and diabetic nephropathy (DN). Polymorphism of Apo E gene is known to influence lipid metabolism. Apo E is polymorphic, consisting of three common isoforms (epsilon2, epsilon3 and epsilon4) encoded by three alleles (2, 3 and 4) in exon 4 on chromosome 19. The aim of this study was to investigate the effect of Apo E polymorphism as a prognostic risk factor for the development of DN. A total of 108 NIDDM patients were recruited from the Nephrology and Endocrinology Departments of our hospital. All subjects were divided into three groups: Group I: diabetes with nephropathy (n:37), group II: diabetes without nephropathy (n:71), group III: controls (n:46). Apo E genotypes were determined by real-time PCR. The epsilon4 allele frequency was significantly higher in-group I (10.8%) than in-group III (2.2%), (p < 0.05). In diabetics without nephropathy, the total cholesterol and LDL cholesterol levels were significantly lower in subjects with epsilon2 alleles than epsilon3 and epsilon4 alleles. In conclusion, the present prospective study indicates that the epsilon4 allele of the Apo E polymorphism is one of the prognostic risk factors involved in the development of DN with type 2 diabetes mellitus.

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.

Associations between apolipoprotein B, apolipoprotein AI, the apolipoprotein B/AI ratio and coronary heart disease: a literature-based meta-analysis of prospective studies

OBJECTIVES

To assess associations of circulating levels of apolipoprotein (apo) AI, apoB and the apoB/AI ratio (apoB/A) with risk of incident coronary heart disease (CHD).

DESIGN

Literature-based meta-analysis of prospective studies.

DATA SOURCES

Prospective studies in essentially general populations that reported on associations between apoAI, apoB or apoB/A and first incident CHD outcomes. Studies were identified by computer-based searches and by manual searches of the relevant literature.

RESULTS

Data from 23 relevant studies were identified. For apoAI, with 6333 CHD cases in 21 studies, comparison of individuals in the bottom third with those in the top third of baseline values yielded a combined relative risk of 1.62 (95% confidence interval: 1.43-1.83), i.e. an inverse association. For apoB, a combined analysis of 6320 CHD cases from 19 studies gave a relative risk of 1.99 (1.65-2.39) for a comparison of individuals in the top third versus those in the bottom third of baseline values. For apoB/A, with 3730 CHD cases from seven studies, a comparison of individuals in the top third versus the bottom third of baseline values gave a combined relative risk of 1.86 (1.55-2.22). These associations were somewhat stronger following correction for within-person variations in apolipoprotein levels. There was evidence of heterogeneity amongst the published studies, but it was only partly explained by available study-level characteristics.

CONCLUSIONS

The present quantitative review suggests the existence of moderately strong associations between baseline levels of each of apoAI, apoB, and apoB/A and risk of CHD. More detailed analysis, perhaps based on individual participant data from prospective studies, could help to overcome several limitations in the present review and to clarify any relevance of these apolipoproteins to disease prediction and aetiology.

Apolipoprotein E polymorphism in the Tunisian population: frequency and effect on lipid parameters

OBJECTIVES

We determined the frequencies of apolipoprotein E (apo E) gene alleles and examined the association between apo E polymorphism and lipid parameters in a sample of the Tunisian population.

DESIGN AND METHODS

Apo E polymorphism was investigated using PCR, and plasma lipid parameters were measured in 122 men and 111 women aged 35 to 87 years.

RESULTS

The allele frequencies were epsilon2: 7.3%, epsilon3: 84.6%, and epsilon4: 8.1%. Apo E polymorphism was associated with significant differences (P<0.001) in total cholesterol, apo B and LDL cholesterol in both men and women. epsilon2 carriers had the lowest mean total cholesterol, apo B and LDL-C concentrations, and subjects with the epsilon4 allele had the highest levels. Triglycerides levels increased with the epsilon4 allele, but this did not reach statistical significance. These results remained unchanged after adjustment for age, body mass index, sex, hypertension, diabetes and smoking. However, in obese subjects (BMI>30 kg/m2), TG concentrations were significantly lower in individuals homozygous for the epsilon3 allele compared to those with the alleles epsilon2 or epsilon4.

CONCLUSION

In this sample of the Tunisian population, the distribution of apo E gene alleles is similar to that observed in Southern European populations with low prevalence of the epsilon4 allele. Variations in the apo E gene play a role in determining plasma lipid levels. These data also suggest that effects of apo E alleles on lipids levels are partly dependent on environmental variables such as BMI. These findings highlight the importance of the gene/environment interaction on the deleterious effect of obesity on cardiovascular risk factors.

The effect of the APOE polymorphism on HDL-C concentrations depends on the cholesterol ester transfer protein gene variation in a Southern European population

BACKGROUND

Apolipoprotein E (ApoE) locus has consistently shown a significant association with low-density lipoprotein cholesterol (LDL-C). However, its impact on high-density lipoprotein cholesterol (HDL-C) has been highly controversial suggesting that it may be context-dependent. We examined the gene-gene interaction between the common ApoE and the CETP polymorphisms in determining HDL-C concentrations in men and women from the general population.

METHODS

550 unrelated Caucasian subjects were randomly selected from a Mediterranean Region in Spain. Plasma lipids, anthropometric, clinical and lifestyle variables were measured. Common ApoE and CETP-TaqIB polymorphisms were determined.

RESULTS

We have found a gene-gene interaction between and ApoE and the CETP loci in determining HDL-C concentrations. Thus, after adjustment for gender, age, body mass index, tobacco smoking, alcohol consumption, physical exercise and medication, carriers of the E4 allele had lower HDL-C concentrations [mean and (standard error): 40.1 (2.6) mg/dL] than E2 subjects [47.7 (3.2) mg/dL; p=0.019], and even lower than those of the E3 subjects [44.7 (1.4) mg/dL; p=0.042], only if they had the B1B1 genotype. However, mean HDL-C concentrations were higher among those with E4 allele carrying the B2 allele at the CETP gene locus [50.5 (2.3) mg/dL], and lower among E2 subjects carrying the B2 allele [45.5 (2.6) mg/dL]. This interaction was observed in both men and women. This gene-gene interaction remained statistically significant even after additional adjustment for triglycerides.

CONCLUSIONS

The effect of the ApoE polymorphism on HDL-C concentrations depends on the CETP polymorphism, explaining some of the controversial results previously reported for this polymorphism.

Linkage analysis of LDL cholesterol in American Indian populations: the Strong Heart Family Study

Previous studies have demonstrated that low density lipoprotein cholesterol (LDL-C) concentration is influenced by both genes and environment. Although rare genetic variants associated with Mendelian causes of increased LDL-C are known, only one common genetic variant has been identified, the apolipoprotein E gene (APOE). In an attempt to localize quantitative trait loci (QTLs) influencing LDL-C, we conducted a genome-wide linkage scan of LDL-C in participants of the Strong Heart Family Study (SHFS). Nine hundred eighty men and women, age 18 years or older, in 32 extended families at three centers (in Arizona, Oklahoma, and North and South Dakota) were phenotyped for LDL-C concentration and other risk factors. Using a variance component approach and the program SOLAR, and after accounting for the effects of covariates, we detected a QTL influencing LDL-C on chromosome 19, nearest marker D19S888 at 19q13.41 [logarithm of odds (LOD) = 4.3] in the sample from the Dakotas. This region on chromosome 19 includes many possible candidate genes, including the APOE/C1/C4/C2 gene cluster. In follow-up association analyses, no significant evidence for an association was detected with the APOE*2 and APOE*4 alleles (P = 0.76 and P = 0.53, respectively). Suggestive evidence of linkage to LDL-C was detected on chromosomes 3q, 4q, 7p, 9q, 10p, 14q, and 17q. These linkage signals overlap positive findings for lipid-related traits and harbor plausible candidate genes for LDL-C.

Apolipoprotein E polymorphism in type 2 diabetic patients of Talca, Chile

Apolipoprotein E (apo E) modulates the metabolism of atherogenic lipoprotein particles and participates in the process of cellular incorporation of specific lipoproteins. Genetic polymorphism of apo E has been reported as an important dyslipidemia genetic marker associated with coronary artery disease. Type 2 diabetes mellitus is a disease with a high incidence and prevalence in the world. The main cause of death in these patients is myocardial stroke and a high incidence of general cardiovascular complications. The purpose of this work was to characterize the genotype of apo E in diabetic patients from Talca, Chile, in order to describe the allelic frequency of the apo E gene and its correlation to the lipids profile. Type 2 diabetic patients (200) were recruited from the Diabetes Program of Talca Hospital, Chile. Apo E genotype was determined by restriction fragment-length polymorphism analysis. A biochemical characterization was performed in all the subjects. Type 2 diabetic patients had elevated levels of glycemia, lipid profile and BMI compared to the control group. The E3/3 genotype and epsilon3 allele had a higher frequency in both groups. The E2/3 and E3/4 genotypes had higher levels of triglyceride (TG) and cholesterol respectively; however, there was not any statistical relationship between them. In conclusion, genotype of apo E in diabetic patients did not differ with healthy; E2/3 and E3/4 genotypes tend to have higher levels of triglyceride and cholesterol respectively. We think that these results corroborate that in the etiology of the dyslipidemia, there is more than one associate genetic marker.

Apolipoprotein E polymorphism modifies the alcohol-HDL association observed in the National Heart, Lung, and Blood Institute Family Heart Study

BACKGROUND

The apolipoprotein E gene (APOE) allele epsilon4 is associated with an increased risk of cardiovascular disease. The presence of the epsilon4 allele has been associated with lower concentrations of HDL cholesterol, but it is not known whether the epsilon4 allele modifies the association between alcohol consumption and HDL-cholesterol concentrations.

OBJECTIVE

The objective of the study was to assess whether the epsilon4 allele modifies the association between alcohol consumption and HDL-cholesterol concentrations.

DESIGN

In a cross-sectional design, we studied 670 men and women aged 26-78 y who participated in the National Heart, Lung, and Blood Institute Family Heart Study to assess whether the epsilon4 allele of the gene APOE modifies the association between alcohol consumption and HDL-cholesterol concentrations. Alcohol data were self-reported, and we used multivariate, generalized estimating equations to assess interactions.

RESULTS

In a model with adjustment for age, sex, body mass index, smoking, exercise, waist-hip ratio, TV viewing, and study site, there was a significant effect of the interaction between the epsilon4 allele and alcohol consumption on HDL cholesterol (P=0.0001). In the absence of the epsilon4 allele, multivariate adjusted means of HDL were 1.24, 1.36, and 1.54 mmol/L among subjects who never drank and those who currently drink 0.1-12 and >12 g alcohol/d, respectively; in the presence of the epsilon4 allele, the corresponding values were 1.19, 1.27, and 1.25 mmol/L.

CONCLUSION

Our data show a significant effect of the interaction between the epsilon4 allele and alcohol consumption on HDL. The increase in HDL associated with alcohol appears to be stronger in subjects without the epsilon4 allele than in those with the epsilon4 allele.

The effect of dietary fat on LDL size is influenced by apolipoprotein E genotype in healthy subjects

LDL particle size is dependent on both genetic factors and environmental factors such as dietary fat composition. The apolipoprotein E (apoE) genotype is a major genetic determinant of LDL size. Thus, the aim of this work was to study whether the apoE genotype interacts with the quantity and quality of dietary fat, modifying LDL size in young healthy subjects. Healthy subjects (n = 84; 66 apoE 3/3, 8 apoE 4/3, 10 apoE 3/2) were subjected to 3 dietary periods, each lasting 4 wk. The first was an SFA-enriched diet (38% fat, 20% SFA), which was followed by a carbohydrate (CHO)-rich diet (30% fat, < 10% SFA, 55% carbohydrate) or a monounsaturated fatty acid (MUFA) olive oil-rich diet (38% fat, 22% MUFA) following a randomized crossover design. At the end of each diet period, LDL particle size and plasma levels of total cholesterol, LDL cholesterol (LDL-C), HDL-C, apoB, apoA-I, and triacylglycerols were determined. LDL particle size was significantly higher (P < 0.04) in subjects with the apoE 4/3 genotype compared with those with apoE 3/3 and apoE 3/2 in the basal state. LDL size was smaller (P < 0.02) after the CHO diet than after the MUFA or SFA diets. After the CHO diet, a significant increase in LDL particle size (P < 0.035) was noted with respect to the MUFA diet in apoE 4/3 subjects, whereas a significant decrease was observed in the apoE 3/3 individuals (P < 0.043). In conclusion, a Mediterranean diet, high in MUFA-fat increases LDL particle size compared with a CHO diet, and this effect is dependent of apoE genotypes.

Obesity modulates the association among APOE genotype, insulin, and glucose in men

OBJECTIVE

Obesity, insulin resistance, and apolipoprotein E (APOE) genotype have all been associated with coronary heart disease. We examined the interaction between obesity and APOE genotype in determining fasting insulin and glucose levels.

RESEARCH METHODS AND PROCEDURES

From 1991 to 1995, 3799 subjects underwent a clinical examination and fasting insulin and glucose measurement. APOE genotypes were determined on 3500 participants. Participants taking oral hypoglycemic drugs or insulin preparations or with the rare APOE2/4 genotype were excluded. Finally, 2929 individuals were included in the present analysis.

RESULTS

In men, we observed a statistically significant interaction between obesity and APOE genotype on insulin and glucose level (p = 0.003 and 0.008, respectively). Obese men with the APOE4 genotype presented with higher levels of insulin and glucose than obese men in the other genotype groups. No association between genotype and insulin or glucose in nonobese men was observed. Obesity was associated with higher insulin levels in the three APOE genotypes groups, whereas obesity was directly associated with glucose in those with the APOE4 genotype. In women, the effect of interaction between APOE genotype and obesity on fasting insulin and glucose was not statistically significant. Obesity was associated with higher levels of fasting insulin and glucose. APOE genotype was not associated with insulin or glucose.

DISCUSSION

Obesity modulates the association between the APOE genotype and fasting insulin and glucose levels in men. Although weight control is important in all people, it may be especially important in APOE4 men to modify potentially elevated fasting insulin and glucose levels.

Apolipoprotein E polymorphisms and mortality in Italian type 2 diabetic patients

AIMS

To determine if apolipoprotein E polymorphism is associated with cardiovascular or all-cause mortality in Italian Type 2 diabetic patients.

METHODS

A prospective study of mortality in Type 2 diabetic patients (n = 433) as a function of apolipoprotein E phenotype, which was assessed at entry into the study. During follow up (10 years), 110 (25.4%) patients died of which 66 (15.2%) were the result of cardiovascular causes. Cause of death was established from death certificates and clinical records. The clinical status of the survivors was determined at the end of the study.

RESULTS

Apolipoprotein E polymorphisms were not associated with excess cardiovascular or all-cause mortality in the Italian Type 2 diabetic patients either in univariate or multivariate analyses. Age, duration of diabetes and glycated haemoglobin levels at entry were the primary determinants of premature mortality in the diabetic population.

CONCLUSIONS

Apolipoprotein E polymorphisms are not markers for premature mortality in Italian Type 2 diabetic patients. The impact of apolipoprotein E mutations may be attenuated by environmental factors, notably a healthier diet, in Italian patients.

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.

Accuracy of lipoprotein lipids and apoproteins in predicting coronary heart disease in diabetic American Indians. The Strong Heart Study

PURPOSE

To evaluate the accuracy of lipoprotein lipids and apoproteins in predicting coronary heart disease (CHD) in diabetic American Indians.

METHODS

This study included 2099 diabetic participants of the Strong Heart Study, which is a longitudinal study of cardiovascular disease (CVD) and its risk factors in American Indians in Arizona, Oklahoma, and South and North Dakota. Diabetic participants with incident CHD (N = 126) were selected as the case group, and those without CHD or any cardiovascular events were the control group (N = 1732). Previous vascular events such as stroke were the sole exclusion criterion (N = 241). Baseline measurements of lipoprotein lipids and apoproteins were used to predict CHD diagnosed at the 4-year follow-up examination by using Receiver-Operating Characteristic (ROC) curve analysis.

RESULTS

The ratio of high-density lipoprotein (HDL) to total cholesterol had the highest area under the ROC curve (0.69 +/- 0.02). The areas for the ratios of HDL to low-density lipoprotein (LDL) cholesterol (0.68 +/- 0.02), apo AI/B (0.66 +/- 0.02), and the single component of total cholesterol (0.64 +/- 0.03) and LDL cholesterol (0.63 +/- 0.05) were not significantly different from the area for HDL/total cholesterol. However, the areas for apo B (0.64 +/- 0.02), HDL cholesterol (0.62 +/- 0.03), triglycerides (0.58 +/- 0.03), and apo AI (0.57 +/- 0.05) were significantly lower than the area for HDL/total cholesterol. Logistic regression analysis indicates that only HDL and LDL cholesterol were significant independent lipoprotein lipid and apoprotein predictors for CHD. The other significant predictors in the model were study center, age, gender, and albuminuria. The ROC area for this model is 0.75.

CONCLUSIONS

HDL and LDL cholesterol were the most important independent predictors for incident CHD in diabetic American Indians. The ratios of HDL/total cholesterol, HDL/LDL cholesterol, and apo AI/B had higher accuracy for predicting CHD. Although the values for all lipoprotein lipids and apoproteins and their ratios were not large enough to definitely predict CHD, they can be used as screening tools for CHD in diabetic American Indians.

Lipoprotein and apolipoprotein abnormalities in familial combined hyperlipidemia: a 20-year prospective study

In order to characterize the lipoprotein abnormalities in familial combined hyperlipidemia (FCHL) and to describe factors associated with the stability of the FCHL phenotype during 20-year follow-up, 287 individuals from 48 families with FCHL originally identified in the early 1970s (baseline) were studied. Hyperlipidemia was defined as lipid-lowering medication use, or > or =age- and sex-specific 90th percentile for triglycerides or cholesterol. Triglyceride, cholesterol and medical history data were obtained at baseline and 20-year follow-up. Additional follow-up measures included HDL-C, LDL-C, LDL particle size, lipoprotein(a), apolipoprotein (apo) A-I, apoB, and apoE polymorphism. Longitudinally, two-thirds of relatives were consistently normolipidemic or hyperlipidemic, and one third were discordant for hyperlipidemic status at baseline and 20-year follow-up. Individuals with hyperlipidemia at baseline and/or follow-up had higher apoB levels than those with consistently normal lipids (P<0.05), whereas small LDL size was associated with concurrent hyperlipidemia. Among individuals who were normolipidemic at baseline, the following variables were independently associated with development of hyperlipidemia over 20 years: older age at baseline, male sex, greater increase in BMI during follow-up, and apoE alleles epsilon 2 or epsilon 4. In conclusion, apoB is associated with hyperlipidemia and apoE polymorphism is associated with later onset of hyperlipidemia in FCHL.

Development of a genetics education workshop curriculum for Native American college and university students

The long-term goal of Genetic Education for Native Americans (GENA), a project funded by the National Human Genome Research Institute (NHGRI), is to provide a balance of scientific and cultural information about genetics and genetic research to Native Americans and thereby to improve informed decision making. The project provides culturally sensitive education about genetic research to Native American medical students and college and university students. Curriculum development included focus groups, extensive review of available curricula, and collection of information about career opportunities in genetics. Special attention was focused on genetic research to identify key concepts, instructional methods, and issues that are potentially troublesome or sensitive for Native Americans. Content on genetic research and careers in genetics was adapted from a wide variety of sources for use in the curriculum. The resulting GENA curriculum is based on 24 objectives arranged into modules customized for selected science-related conference participants. The curriculum was pretested with Native American students, medical and general university, health care professionals, and basic scientists. Implementation of the curriculum is ongoing. This article describes the development and pretesting of the genetics curriculum for the project with the expectation that the curriculum will be useful for genetics educators working in diverse settings.

Gene-diet interactions and plasma lipoproteins: role of apolipoprotein E and habitual saturated fat intake

To test whether plasma lipoprotein levels and low density lipoprotein (LDL) particle size are modulated by an interaction between habitual saturated fat intake and apolipoprotein E (APOE) genotype, we studied 420 randomly selected free-living Costa Ricans. The APOE allele frequencies were 0.03 for APOE2, 0.91 for APOE3, and 0.06 for APOE4. The median saturated fat intake, 11% of energy, was used to divide the population into two groups, LOW-SAT (mean intake 8.6% energy) represents those below median intake, and HIGH-SAT (mean intake 13.5%) represents those above median intake. Significant interactions between APOE genotype and diet were found for VLDL (P = 0.03) and HDL cholesterol (P = 0.02). Higher saturated fat intake was associated with higher VLDL cholesterol (+29%) and lower HDL cholesterol (-22%) in APOE2 carriers, while the opposite association was observed in APOE4 carriers (-31% for VLDL cholesterol and +10% for HDL cholesterol). Higher saturated fat intake was associated with smaller LDL particles (-2%, P < 0.05) in APOE2 carriers, and larger LDL particles (+2%, P < 0.05) in APOE4 carriers, but the gene-diet interaction was not statistically significant (P = 0.09). Higher saturated fat intake was associated with higher LDL cholesterol in all genotypes (mean +/- SEM, LOW-SAT 2.61 +/- 0.05 vs. HIGH-SAT 2.84 +/- 0.05 mmol/L, P = 0.009). These data suggest that the APOE2 allele could modulate the effect of habitual saturated fat on VLDL cholesterol and HDL cholesterol in a population with an average habitual total fat intake of less than 30%.

Smoking influences the association between apolipoprotein E and lipids: the National Heart, Lung, and Blood Institute Family Heart Study

Apolipoprotein E allele 4 (apo epsilon4) and smoking each have been associated with an unfavorable lipid profile. We used data collected on 1,472 subjects in the National Heart, Lung, and Blood Institute Family Heart Study to assess whether smoking interacts with apo epsilon4 to influence the levels of plasma lipids. We dichotomized smoking and apo epsilon4 and used analysis of covariance to estimate the means of lipids. Smokers had lower body mass index, were younger, and consumed less fruits and vegetables. Among individuals without apo epsilon4, comparing nonsmokers with smokers, mean low density lipoprotein cholesterol (LDL) was 129.3 and 134.4 mg/dL, respectively, for women and 126.1 and 127.6 mg/dL, respectively, for men. Among subjects with an apo epsilon4 allele, corresponding means were 132.0, and 152.9 mg/dL, respectively, for women and 131.3 and 137.3 mg/dL, respectively, for men (Pfor interaction <0.001 for women and 0.11 for men). A similar interaction was observed for total cholesterol among women (P = 0.02). This study shows a statistically significant effect modification of the relation of apo epsilon4 to LDL and total cholesterol by smoking among women. Smoking may enhance genetic susceptibility to an unfavorable lipid profile among subjects with apo epsilon4.

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.

High heterogeneity of apolipoprotein E gene frequencies in South American Indians

The apolipoprotein E (APOE) polymorphism was investigated in 186 individuals from six South American Indian tribes, and the results integrated with those previously presented for this ethnic group. The three APOE alleles commonly reported in other populations were also observed in South Amerindians with a highly heterogeneous distribution. As in other populations, APOE*3 was the most common allele (51-98%) followed by APOE*4 (2-47%). These two isoforms were identified in all tribes, but APOE*2 was observed among the Wai Wai (2%) and Mataco (4%) only. No previous indications of inter-ethnic admixture were observed among the Wai Wai, but the introduction of this allele among the Mataco through non-Indian sources cannot be excluded.

The apolipoprotein E4 allele is not associated with an abnormal lipid profile in a Native American population following its traditional lifestyle

The apolipoprotein E4 allele is associated in industrialized countries with an elevated LDL cholesterol concentration and an increased cardiovascular risk. Our purpose in this study was to assess the influence of the genetic variation at the APOE gene locus on the lipid profile of a Native American rural population. We examined plasma lipid levels and the common apo E alleles in 142 healthy randomly selected adults living in their native communities in western Mexico. Their age was 38+/-17 years and the BMI 25.7+/-4.5 kg/m2. Plasma cholesterol, triglycerides, LDL C and HDL C were 165+/-29.6, 126+/-83, 98+/-26 and 42+/-12.7 mg/dl respectively. Ninety-one per cent of the subjects had Lp(a) concentrations below 20 mg/dl and 30% had levels lower than 2 mg/dl. The most common APOE genotype was E3/3 (63%), followed by E3/4 (30.1%). The prevalence of the E2 allele was very low (2.3%). No difference was observed in LDL C concentrations between the E3/E3 and E3/E4 subjects; however carriers of the E2/3 genotype had lower LDL C levels. Similar results were obtained for cholesterol and apo B levels. In summary, the increased LDL C levels associated with the E4 allele in previous studies were not observed in a population with non-westernized habits. Environmental factors, such as diet and lifestyle, could outweigh the hypercholesterolemic predisposition resulting from the presence of the apo E4 allele.

Smaller, denser LDL particles are not a risk factor for cardiovascular disease in healthy nonagenarian women of the Cremona Population Study

We evaluated LDL particle size and its relation with other established risk factors for cardiovascular disease in a group of healthy nonagenarian ( > or = 90 years) women participating in the Cremona Population Study. A group of younger healthy postmenopausal women (45-75 years) was used as control group. Nonagenarian women had significantly lower body mass index, systolic and diastolic blood pressure, and fasting insulin concentrations. Plasma total, LDL and HDL cholesterol, apo AI and apo B concentrations, and LpAI and LpAI:AII particles were significantly lower in the nonagenarian group as well. LDL particle size (262.7+/-0.9 vs. 270.1+/-1.1 A) was also lower in the nonagenarian group. The presence of the E4 isoform of apo E in the nonagenarian group resulted in significantly higher levels of plasma apo AI and LpAI:AII particles, and a trend toward larger LDL particles, and a lower diastolic blood pressure. In conclusion, smaller and denser LDL particles might not represent an important risk factor for cardiovascular disease in healthy nonagenarian women of the Cremona Population Study, characterised by a reduced number of LDL particles and other protective factors, like low systolic and diastolic blood pressure, body mass index, and plasma insulin levels.

Lipid profiles reflecting high and low risk for coronary heart disease: contribution of apolipoprotein E polymorphism and lifestyle

To elucidate the role of modifiable factors and the apolipoprotein E polymorphism in explaining lipid profiles reflecting low, average and high risk for coronary heart disease, we selected subjects from a large population-based study. Subjects with low total cholesterol (TC) (< 15th percentile) and high HDL-cholesterol levels (> 85th percentile) were randomly selected (n = 99) and represent subjects with a low risk lipid profile. Additionally, 95 subjects with total and HDL-cholesterol levels in the 15% around the population-median (median risk lipid profile) and 100 subjects with high TC (> 85th percentile) and low HDL-cholesterol levels (< 15th percentile) (high risk lipid profile) were selected. Compared with E3/3 subjects, the likelihood for a low risk lipid profile was considerably higher (odds ratio 14.3; 2.6-79) in female, but not in male E2-carriers (1.5; 0.3-6.7). Smoking and alcohol consumption were independently associated with a low risk lipid profile in both genders, physical inactivity only in women. The odds ratio for a high risk lipid profile was elevated in male E4-carriers (4.9; 1.1-23) only. In addition to the E4 isoform, smoking and physical inactivity, overweight was the main determinant for a high risk lipid profile (odds ratio 16.8; 3.4-82). Male overweight E4-carriers had a 50 times higher likelihood of a high risk lipid profile than E3/3 men of normal weight. In women, only overweight was independently associated with a high risk lipid profile. Our results suggest that both modifiable factors and the apolipoprotein E polymorphism contribute to a lipid profile, reflecting low, average and high risk for coronary heart disease, but effects may be gender-specific.