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

An Examination of Stroke Risk and Burden in South Asians

BACKGROUND

South Asians (India, Pakistan, Sri Lanka, Bangladesh, Nepal, and Bhutan) are at a disproportionately higher risk of stroke and heart disease due to their cardiometabolic profile. Despite evidence for a strong association between diabetes and stroke, and growing stroke risk in this ethnic minority-notwithstanding reports of higher stroke mortality irrespective of country of residence-the explanation for the excess risk of stroke remains unknown.

METHODS

We have used extensive literature review, epidemiologic studies, morbidity and mortality records, and expert opinions to examine the burden of stroke among South Asians, and the risk factors identified thus far.

RESULTS

We summarize existing evidence and indicate gaps in current knowledge of stroke epidemiology among South Asian natives and immigrants.

CONCLUSIONS

This research focuses attention on a looming epidemic of stroke mainly due to modifiable risk factors, but also new determinants that might aggravate the effect of vascular risk factors in South Asians causing more disabling strokes and death.

Clinical effect of cerebrovascular atherosclerosis on cognition in Alzheimer's disease

BACKGROUND

The association between cerebrovascular atherosclerosis and Alzheimer's disease (AD) has been examined in many cross-sectional studies; however, there are few data regarding the role of cerebrovascular atherosclerosis on the longitudinal course of cognitive decline in AD. The aim of this study was to examine the progression of cognitive function in AD patients with cerebrovascular atherosclerosis compared to those without atherosclerosis over a two-year period.

METHODS

Forty-seven AD patients with cerebrovascular atherosclerosis and 81 AD patients without atherosclerosis were assessed for cognitive function at the time of diagnosis and again at follow-up after two years. The cognitive functions were evaluated by neuropsychological tests including mini-mental state examination (MMSE) and clinical dementia scale (CDR).

RESULTS

Repeated-measures multivariate analyses showed that there was a significant group-by-time interactions for the temporal changes of the MMSE and CDR between the two groups. The group-by-time interactions remained significant when the atherosclerotic patients were sub-classified into either an extracranial stenosis (EC) group or an intracranial stenosis(IC) group. Comparing either the EC or IC group with the non-atherosclerosis group, there were no main effects by time or group alone, but there were significant group-by-time interactions for the MMSE and CDR.

CONCLUSIONS

Cognitive function worsened more in terms of progressive impairment in AD patients with cerebrovascular atherosclerosis compared to AD patients without cerebrovascular atherosclerosis, regardless of whether the atherosclerosis was extracranial or intracranial.

Association between apolipoprotein E gene polymorphism and myocardial infarction

We investigated apolipoprotein E (APOE) genotypic influence on myocardial infarction risk in South India, where the disease is emerging as a major threat to the public health care system. The study included 412 subjects: 202 myocardial infarction patients and 210 age- and sex-matched controls. DNA was isolated, the polymorphism of the APOE gene was subjected to PCR, and lipid levels were evaluated. The prevalence of E3/E4 genotypes in patients (18.3%) was 1.5-fold that of controls (11.0%, p < 0.05), and the prevalence of E2/E3 genotypes was higher in controls (6.7%) than in patients (4%). The ε4 allele was significantly associated with myocardial infarction: χ(2) = 12.4; OR 2.2 (CI 95%: 1.4-3.4), p < 0.004, for ε4 versus ε3 and χ(2) = 5.7; OR 2.7 (CI 95%: 1.1-6.5), p > 0.01, for ε4 versus ε2. A significant association of the ε4 allele, especially the E3/E4 genotype, with myocardial infarction was observed.

Premature coronary artery disease and familial hypercholesterolemia: need for early diagnosis and cascade screening in the Indian population

Cardiovascular disease (CVD) is the leading cause of death in India, accounting for 28% of mortality. The average age of onset of CVD is younger (below 55 years) among Indians than in other populations. This may be due to bad lifestyle, genetic factors, or both. Hypertension, smoking, diabetes, and physical inactivity have been identified as modifiable risk factors for heart disease. Hypercholesterolemia is the most common and treatable cause of heart disease. Genetic factors that lead to hypercholesterolemia have not been fully studied in India. Familial Hypercholesterolemia results from mutations in the LDL receptor, ApoB, PCSK9, and ApoE genes. There is an urgent need to screen subjects with premature CAD and their relatives in India for the presence of FH, identify the mutations that lead to high cholesterol, and carry out cascade screening in the at-risk relatives. Those harbouring mutations in the above genes can be treated to lower the cholesterol levels, prevent early CVD, and avoid death. A programme based on these lines has been initiated in Delhi.

Variable frequencies of apolipoprotein E genotypes and its effect on serum lipids in the Guangxi Zhuang and Han children

Guangxi Zhuang, the largest ethnic minority in China, is located in the southern part of the country, and well-known to the world as the longevity village. Studies of apolipoprotein E (APOE) polymorphism in adults suggest the lower frequencies of E4 allele and E4/E4 genotype may account, in part, for the favorable lipid profiles of Guangxi Zhuang. However, the effect of APOE polymorphism on serum lipids in the Guangxi Zhuang children is yet unknown to date. In the present study, genomic DNA was extracted from 278 Guangxi Zhuang and 200 Guangxi Han children. APOE genotypes were determined by PCR-restriction fragment length polymorphism (RFLP) analysis. The fasting serum lipoprotein a [Lp(a)], total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), apolipoprotein A1 (apoA1) and apoB were measured. Our results demonstrated that no significant differences in serum lipids were observed between the Guangxi Zhuang and Han children. The E4/E4 and E4/E3 genotypic frequencies were significantly lower in the Guangxi Zhuang children compared with the Guangxi Han children, whereas for E2/E2, E3/E2 and E4/E2 genotypic frequencies the opposite was presented. Though no significant differences in serum lipid concentrations were found for variant alleles both in the Guangxi Zhuang and Han children, the trend was observed in the association of higher levels of Lp(a), TC, TG and LDL-C with E4 allele in the Guangxi Zhuang children. In conclusion, a significant heterogeneity in APOE genetic variation indeed exists between the Guangxi Zhuang and Han ethnic group. The E4 allele may serve as a genetic marker for susceptibility to higher lipid profiles in the Guangxi Zhuang children. Lifestyle should be modified, according to APOE polymorphism even in the young children.

Apolipoprotein E gene polymorphism and the risk of intracerebral hemorrhage in the Chinese population

Prior studies investigating the association between apolipoprotein E (APOE) gene polymorphism and the risk of intracerebral hemorrhage (ICH) have been inconsistent and limited to small sample sizes. The aim of this study was to test the hypothesis that APOE gene polymorphisms are associated with the risk of ICH in Chinese Han patients. We enrolled 180 ICH patients and 180 controls. APOE genotype was determined by using a polymerase chain reaction-restriction fragment length polymorphism assay. ICH patients had a significantly lower frequency ɛ3/ɛ3 [odds ratio (OR)=0.45, 95% confidence interval (CI)=0.28, 0.71; p=0.001] and ɛ3 allele (OR=0.51, 95% CI=0.35, 0.76; p=0.001) than healthy controls. ICH patients also had a significantly higher frequency ɛ3/ɛ4 (OR=3.61, 95% CI=1.89, 6.88; p<0.001) and ɛ4 allele (OR=3.00, 95% CI=1.76, 5.13; p<0.001) than healthy controls. This study suggests that the APOE genotype is associated with the risk of ICH in Chinese Han patients.

Apolipoprotein E gene polymorphism and dyslipidaemia in adult Asian Indians: A population based study from Calcutta, India

AIM:

The study was aimed to determine the association of Apolipoprotein E (apo E) gene polymorphisms on lipid levels in Asian Indian population.

METHODS:

A total of 350 (184 males and 166 females) adult (30 years and above) Asian Indians of Calcutta and suburb participated in the study. Anthropometric measures, lipids profiles, and blood glucose measures were collected. Out of 350 subjects, a sample of 70 individuals was selected randomly for genotyping after adjusting for age and sex. The apo E gene polymorphisms were determined by agarose gel electrophoresis.

RESULTS:

The apo E polymorphism showed significant association with dyslipidaemia (P=0.0135) with ε3/4 combination has had the highest occurrence of dyslipidaemia and metabolic syndrome (MS) followed by ε4/4 <ε3/3 <ε2/4 <ε2/3 in decreasing order.

CONCLUSIONS:

The ε4 allele of apo E gene independent of other risk factors is associated with dyslipidaemia in particular with low HDLc and high TC: HDLc ratio.

A cross-sectional investigation of regional patterns of diet and cardio-metabolic risk in India

Background

The role of diet in India's rapidly progressing chronic disease epidemic is unclear; moreover, diet may vary considerably across North-South regions.

Methods

The India Health Study was a multicenter study of men and women aged 35-69, who provided diet, lifestyle, and medical histories, as well as blood pressure, fasting blood, urine, and anthropometric measurements. In each region (Delhi, n = 824; Mumbai, n = 743; Trivandrum, n = 2,247), we identified two dietary patterns with factor analysis. In multiple logistic regression models adjusted for age, gender, education, income, marital status, religion, physical activity, tobacco, alcohol, and total energy intake, we investigated associations between regional dietary patterns and abdominal adiposity, hypertension, diabetes, and dyslipidemia.

Results

Across the regions, more than 80% of the participants met the criteria for abdominal adiposity and 10 to 28% of participants were considered diabetic. In Delhi, the "fruit and dairy" dietary pattern was positively associated with abdominal adiposity [highest versus lowest tertile, multivariate-adjusted OR and 95% CI: 2.32 (1.03-5.23); P_trend = 0.008] and hypertension [2.20 (1.47-3.31); P_trend < 0.0001]. In Trivandrum, the "pulses and rice" pattern was inversely related to diabetes [0.70 (0.51-0.95); P_trend = 0.03] and the "snacks and sweets" pattern was positively associated with abdominal adiposity [2.05 (1.34-3.14); P_trend = 0.03]. In Mumbai, the "fruit and vegetable" pattern was inversely associated with hypertension [0.63 (0.40-0.99); P_trend = 0.05] and the "snack and meat" pattern appeared to be positively associated with abdominal adiposity.

Conclusions

Cardio-metabolic risk factors were highly prevalent in this population. Across all regions, we found little evidence of a Westernized diet; however, dietary patterns characterized by animal products, fried snacks, or sweets appeared to be positively associated with abdominal adiposity. Conversely, more traditional diets in the Southern regions were inversely related to diabetes and hypertension. Continued investigation of diet, as well as other environmental and biological factors, will be needed to better understand the risk profile in this population and potential means of prevention.

Apolipoprotein E epsilon 4 allele and outcomes of traumatic spinal cord injury in a Chinese Han population

The association between apolipoprotein E (APOE) epsilon 4 (ε4) allele and outcomes of traumatic spinal cord injury (SCI) is still controversial and ambiguous. The objective of this study was to test the hypothesis that APOE polymorphisms are associated with outcomes after SCI in Chinese Han patients. APOE polymorphisms were determined in 100 patients with cervical SCI (C3-C8). The genotype frequency of this polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism assay. Patients with an APOE ε4 allele had significantly less motor recovery during rehabilitation than did patients without an APOE ε4 allele (mean 3.7 vs. 6.1; P = 0.04) and a longer rehabilitation length of stay (LOS) (mean 117.4 vs. 94.5; P = 0.02), but better sensory-pinprick recovery (mean 6.1 vs. 4.0; P = 0.03). There were no significant differences by APOE ε4 allele status in sensory-light touch recovery or acute LOS. This study suggests that the APOE ε4 allele is associated with outcomes after SCI and longer rehabilitation LOS in Chinese Han patients.

Polymorphism in apolipoprotein E among migraineurs and tension-type headache subjects

Nitric oxide plays an important role in the pathogenesis of migraine as well as tension-type headache. Studies suggest that the expression of molecules involved in the pathogenesis of headache, i.e., nitric oxide and interleukin, is influenced by apolipoprotein E (APOE) and is gene specific. Hence, we hypothesized that APOE polymorphism may be associated with migraine as well as tension-type headache.The study sample comprised of three groups: migraineurs, tension-type headache subjects as well as a healthy control group. A total of 50 subjects in each group were included after screening for the inclusion and exclusion criteria. None of the subjects was a blood relative of any other subject included in the present study. Their venous blood was drawn and stored at −20°C. Genomic DNA extraction was performed with a commercial kit and simple sequence-specific primer PCR was performed to assess the APOE polymorphism. Data were analyzed with the help of SPSS V11.0 for Windows. χ² test and logistic regression analysis were run. The results of the study showed that APOE ε2 gene increases the risk of migraine as compared to the control group and the tension-type headache group (OR = 4.85; 95% CI = 1.92–12.72; P < 0.001 and OR = 2.31; 95% CI = 1.08–4.94; P = 0.01, respectively). Interestingly, APOE ε4 gene was protective against migraine as well as tension-type headache. This study shows that APOE ε2 gene increases the risk of migraine, while APOE ε4 gene is protective against migraine and tension-type headache. Further research is required to confirm the findings of the present study in a larger sample and to elucidate the role of APOE polymorphism in headache.

Synergistic effect between apolipoprotein E and apolipoprotein A1 gene polymorphisms in the risk for coronary artery disease

Alterations in lipid metabolism and genetic predisposition are major risk factors for coronary artery disease (CAD). Variations in genes involved in lipid metabolism may act synergistically to confer risk or protection against CAD. The objective of the present study was to determine such interactions in variants of apolipoprotein E and apolipoprotein A1 genes. One hundred and forty subjects with clinically confirmed CAD and 100 unrelated normal subjects participated in the study. Multiple regression analysis was used to relate lipid and apolipoprotein profiles with genotypes. Odd ratios were calculated for various combinations of ApoE and ApoA1 genotypes. Prevalence of ApoE 'E4' and ApoA1 'A' and 'T' alleles was significantly higher in patients than controls. Serum apolipoprotein E and apolipoprotein A1 levels were significantly lower in CAD patients than controls. When lipid parameters were related to genotypes, the polymorphisms associated to various markers were in agreement with previous reports. ApoE 2/4 genotype in combination with either ApoA1 heterozygous GA or CT genotype conferred higher risk of CAD. E3 allele in homozygous or heterozygous state in combination with ApoA1+83 CC genotype conferred highest protection (P < 0.05). Thus, it appears that ApoE and ApoA1 gene variants may act synergistically to associate with risk and protection against CAD.

Evaluation of efficacy and safety of fixed dose lovastatin and niacin(ER) combination in asian Indian dyslipidemic patients: a multicentric study

Asian Indian dyslipidemia is characterized by: borderline high low-density lipoprotein (LDL) cholesterol and apolipoprotein (apo) B; high triglycerides, low high-density lipoprotein (HDL) cholesterol and apoA1; and high lipoprotein(a) (lp[a]). We performed a controlled multicentric trial in India to evaluate the efficacy and safety of a fixed dose combination of lovastatin and niacin extended release (niacin^ER) formulation in patients with moderate to severe dyslipidemia. Consecutive subjects that satisfied the selection criteria, agreed to an informed consent, and with no baseline presence of liver/renal disease or heart failure were enrolled in the study. After a 4-week run-in period there were 142 patients with LDL levels ≥130 mg/dL. Eleven patients were excluded because of uncontrolled hyperglycemia and 131 patients were recruited. After baseline evaluation of clinical and biochemical parameters all subjects were administered lovastatin (20 mg) and niacin^ER (500 mg) combination once daily. Dose escalation was done on basis of lipid parameters at 8 weeks and in 11 patients increased to lovastatin (20 mg) and niacin^ER (1000 mg). An intention-to-treat analysis was performed and data was analyzed using nonparametric Wilcoxon signed rank test. Thirteen patients (10%) were lost to follow-up and 4 (3%) withdrew because of dermatological adverse effects: flushing, pruritus, and rash. The mean values of various lipid parameters (mg/dL) at baseline, and at weeks 4, 12, and 24 respectively were: total cholesterol 233.9 ± 27, 206.3 ± 27, 189.8 ± 31, and 174.9 ± 27 mg/dL; LDL cholesterol 153.4 ± 22, 127.3 ± 21, 109.2 ± 27, and 95.1 ± 23 mg/dL; triglycerides 171.1 ± 72, 159.5 ± 75, 149.2 ± 45, and 135.2 ± 40 mg/dL; HDL cholesterol 45.6 ± 7, 48.9 ± 7, 51.6 ± 9, and 53.9 ± 10 mg/dL; lp(a) 48.5 ± 26, 40.1 ± 21, 35.4 ± 21, and 26.9 ± 19 mg/dL; and apoA1/apoB ratio 0.96 ± 0.7, 1.04 ± 0.4, 1.17 ± 0.5, and 1.45 ± 0.5 (p < 0.01). The percentage of decline in various lipids at 4, 12, and 24 weeks was: total cholesterol 11.8%, 18.8%, and 25.2%; LDL cholesterol 17.0%, 28.8%, and 38.0%; triglyceride 6.8%, 12.8%, and 21.0%; lp(a) 17.5%, 26.9%, and 44.5% respectively (p < 0.01). HDL cholesterol and apoA1/apoB increased by 7.2%, 13.1%, and 18.2%; and 7.9%, 21.9%, and 51.6% respectively (p < 0.01). Target LDL levels (<100 mg/dL in subjects with manifest coronary heart disease or diabetes; <130 mg/dL in subjects with >2 risk factors) were achieved in 92 (80.7%) patients. No significant changes were observed in systolic or diastolic blood pressure, blood creatinine, transaminases, or creatine kinase. A fixed dose combination of lovastatin and niacin^ER significantly improved cholesterol lipoprotein lipids as well as lp(a) and apoA1/apoB levels in Asian Indian dyslipidemic patients. Satisfactory safety and tolerability profile in this population was also demonstrated.

Medial Temporal Lobe Atrophy, Apolipoprotein Genotype, and Plasma Homocysteine in Sri Lankan Patients with Alzheimer's Disease

The authors studied the association of Alzheimer's disease (AD) with total plasma homocysteine (tHcy) and apolipoprotein E (apoE) genotype, and the usefulness of measuring medial temporal lobe thickness (MTL) thickness for the diagnosis of AD in Sri Lankan patients. Using criteria of the NINCDS-ADRDA, 23 AD patients and 21 controls were recruited. All underwent MTL-oriented computed tomographic (CT) scans, measurement of plasma tHcy, and apoE genotyping. Mean plasma tHcy was significantly higher in AD patients than controls (p=.001). This association was independent of age, sex, body mass index (BMI), serum folate and vitamin B12, and serum creatinine. The frequency of apoE4 allele was significantly higher (p=.003) in AD patients, and the adjusted odds ratio of AD for the presence of one or more apoE4 alleles compared with none was 10.39 (95% CI 1.77-61.10; p=.010). The mean minimum MTL thickness was significantly higher in control subjects compared to that of AD patients (p<.001). This first report of apoE4, plasma tHcy, MTL thickness, and AD from Sri Lanka shows that high plasma tHcy, the presence of apoE4 allele, and MTL atrophy are associated with AD.

Circle of Willis atherosclerosis: association with Alzheimer's disease, neuritic plaques and neurofibrillary tangles

The role of intracranial atherosclerosis in Alzheimer's disease (AD) has been a subject of debate since the first decade of the last century. The initial "vascular hypothesis" of AD was rejected after a series of mid-twentieth century gross anatomical postmortem studies that showed an inconstant relationship between intracranial atherosclerosis and senile dementia. These early studies did not utilize statistical methods, however, and the investigators did not appear to consider the possibility that intracranial atherosclerosis might have a probabilistic, rather than an absolute, effect on AD risk. Recent studies by three independent groups have found a significant statistical association between postmortem measures of circle of Willis atherosclerosis and AD. The present study was undertaken to further address the validity of this association in a large autopsy series, including cases diagnosed neuropathologically with vascular dementia (VaD) and non-AD dementias. Postmortem gross anatomical grading of circle of Willis atherosclerosis was performed in 397 subjects classified by neuropathological diagnosis, including 92 non-demented elderly controls, 215 with AD, 30 with VaD and 60 with non-AD dementias. Circle of Willis atherosclerosis was more severe in subjects with AD and VaD than in control subjects, while it was equivalent between control subjects and subjects with non-AD dementias. Increasing atherosclerotic grade increased the odds ratios (OR) for the diagnoses of both AD and VaD and also increased the ORs for both increased neuritic plaque density and higher Braak neurofibrillary tangle stage. The significance of these associations was retained after consideration of the effects of age, gender and the apolipoprotein E-epsilon4 allele. The results suggest that the statistical association between intracranial atherosclerosis and AD is not an artifact of diagnostic misclassification or of unequal distribution of the apolipoprotein E-epsilon4 allele.

Insulin resistance syndrome (metabolic syndrome) and obesity in Asian Indians: evidence and implications

OBJECTIVES

This review describes prevalence, determinants, and possible pathophysiologic mechanisms and suggests management and research directions for insulin resistance syndrome (metabolic syndrome) in Asian Indians.

METHOD

We reviewed the topic using the terms Asian Indians, Asians, South Asians, and Indians coupled with the terms insulin resistance, hyperinsulinemia, metabolic syndrome, and obesity from the databases Pubmed (National Library of Medicine, Bethesda, MD, USA) and Current Contents (Institute for Scientific Information, Thomson Scientific, Philadelphia, PA, USA) and from non-indexed publications of the medical research and governmental institutions in India.

RESULTS

Asian Indians have a high prevalence of insulin resistance syndrome that may underlie their greater than normal tendency to develop diabetes mellitus and early atherosclerosis. Important reasons could be their excess body fat and adverse body fat patterning including abdominal adiposity even when the body mass index is within the currently defined normal limits. Some of these features have been reported at birth and childhood. Whether Asian Indians also have tendency to develop insulin resistance de novo, independent of total or regional adiposity, needs further investigation. Underlying genetic tendency or early-life adverse events may contribute to such a phenotype, but lifestyle factors alone or modulated by inherited factors appear to play an important role because obesity and dyslipidemia become worse with urbanization and migration. Systemic stress may contribute to insulin resistance syndrome in the intra-country and inter-country migrant Asian Indians.

CONCLUSIONS

High prevalences of excess body fat, adverse body fat patterning, hypertriglyceridemia, and insulin resistance beginning at a young age have been consistently recorded in Asian Indians irrespective of their geographic locations. These data suggest that primary prevention strategies should be initiated early in this ethnic group.