Apolipoprotein E gene polymorphism effects triglycerides but not CAD risk in Caucasian women younger than 65 years

Modifiable and Non-Modifiable Risk Factors for Premature Coronary Heart Disease (PCHD): Systematic Review and Meta-Analysis

AIM

We aimed to compare the prevalence of modifiable and non-modifiable coronary heart disease (CHD) risk factors among those with premature CHD and healthy individuals.

METHODS

PubMed, CINAHL, Embase, and Web of Science databases were searched (review protocol is registered in PROSPERO CRD42020173216). The quality of studies was assessed using the National Heart, Lung and Blood Institute tool for cross-sectional, cohort and case-control studies. Meta-analyses were performed using Review Manager 5.3. Effect sizes for categorical and continuous variables, odds ratio (OR) and mean differences (MD)/standardised mean differences (SMD) with 95% confidence intervals (CI) were reported.

RESULTS

A total of n=208 primary studies were included in this review. Individuals presenting with premature CHD (PCHD, age ≤65 years) had higher mean body mass index (MD 0.54 kg/m2, 95% CI 0.24, 0.83), total cholesterol (SMD 0.27, 95% CI 0.17, 0.38), triglycerides (SMD 0.50, 95% CI 0.41, 0.60) and lower high-density lipoprotein cholesterol (SMD 0.79, 95% CI: -0.91, -0.68) compared with healthy individuals. Individuals presenting with PCHD were more likely to be smokers (OR 2.88, 95% CI 2.51, 3.31), consumed excessive alcohol (OR 1.40, 95% CI 1.05, 1.86), had higher mean lipoprotein (a) levels (SMD 0.41, 95% CI 0.28, 0.54), and had a positive family history of CHD (OR 3.65, 95% CI 2.87, 4.66) compared with healthy individuals. Also, they were more likely to be obese (OR 1.59, 95% CI 1.32, 1.91), and to have had dyslipidaemia (OR 2.74, 95% CI 2.18, 3.45), hypertension (OR 2.80, 95% CI 2.28, 3.45), and type 2 diabetes mellitus (OR 2.93, 95% CI 2.50, 3.45) compared with healthy individuals.

CONCLUSION

This meta-analysis confirms current knowledge of risk factors for PCHD, and identifying these early may reduce CHD in young adults.

Association between apolipoprotein E gene polymorphism and the risk of coronary artery disease in Hakka postmenopausal women in southern China

Background

Apolipoprotein E (APOE) is involved in the pathogenesis of atherosclerosis and conveys a higher risk of coronary artery disease (CAD). The aim of the present study was to investigate the possible association between APOE gene polymorphism and the risk of CAD in postmenopausal Hakka women in southern China.

Methods

The APOE genotypes of 653 CAD patients and 646 control participants were determined by the polymerase chain reaction (PCR) and hybridization to a Sinochip.

Results

The prevalence of each APOE genotype differed between CAD patients and control participants (P = 0.011). The E3/E3 genotype was the most common and the E2/E2 genotype was the least common in the study sample. Moreover, the presence of ε4 allele was associated with higher serum concentrations of triglycerides (TG), total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C), and lower concentration of high-density lipoprotein-cholesterol (HDL-C). Multiple logistic regression analysis revealed that participants with ε4 allele have a significantly higher risk of CAD after adjustment for the presence of diabetes mellitus and hypertension, and their serum uric acid, TC, and LDL-C concentrations (adjusted odds ratio (OR) 1.50, 95% confidence interval (CI) 1.10–2.05, P = 0.010).

Conclusions

The present results suggest that APOE polymorphism is associated with a higher risk of CAD in postmenopausal Hakka women in southern China.

Bosnian study of APOE distribution (BOSAD): a comparison with other European populations

BACKGROUND

The ε2, ε3 and ε4 alleles of APOE gene have been associated with several diseases in different populations. Data on the frequency of alleles are used in both a clinical and evolutionary context. Although the data on frequency of these alleles are numerous, there are no reports for the population of Bosnia and Herzegovina.

AIM

To estimate the frequency of APOE alleles in a healthy Bosnian population and compare it to data for other European populations.

SUBJECTS AND METHODS

Overall, 170 unrelated Bosnian subjects (108 female and 62 male), aged 53.0 (±5.0) years were included in this study. Genotypes were determined by real-time PCR.

RESULTS

In our group the prevalence of heterozygotes E2/E3, E2/E4 and E3/E4 was 20.6%, 3.5% and 12.9%, respectively, while the prevalence of homozygotes E2/E2, E3/E3, E4/E4 was 0.6%, 61.2% and 1.2%, respectively, with a mean frequency of ε2, ε3 and ε4 alleles of 12.6%, 78.0% and 9.4%, respectively.

CONCLUSIONS

In studied European populations we observed a linear, gradually increasing trend in the frequency of ε4 allele from South to North (Pearson's test 0,7656, p value <0.00001), and the Bosnian population fits into this pattern perfectly.

Association between apolipoprotein E polymorphisms and premature coronary artery disease: a meta-analysis

BACKGROUND

Although several studies have explored the genetic polymorphisms of apolipoprotein E (APOE) and their impact on premature coronary artery disease (PCAD), there is still some controversy regarding the significance of their association. Our aim is to estimate the association between APOE polymorphisms and PCAD via meta-analysis.

METHODS

All relevant case-control studies and cohort studies published in Chinese or English prior to March 2016 were searched for in electronic databases. Detailed information concerning each piece of literature was independently extracted by two researchers. We used STATA11.0 to process all data and to determine the pooled odds ratio (OR). Altogether, four genetic models were applied to calculate OR and 95% confidence interval (CI): (1) ε2 allele vs. ε3 allele; (2) ε2 carriers vs. ε3/3; (3) ε4 allele vs. ε3 allele; (4) ε4 carriers vs. ε3/3.

RESULTS

Eighteen studies concerning APOE polymorphisms and their impact on PCAD were included in the final analysis. The pooled analysis displayed that the ε2 allele and ε2 carriers increased the risk of PCAD significantly among Asians (OR 1.54; 95% CI, 1.09-2.17; OR 1.65; 1.10-2.47), while they showed protective effects on PCAD in Caucasians (OR 0.77; 95% CI, 0.62-0.95; OR 0.69; 0.54-0.89). Subjects with the ε4 allele and ε4 carriers showed significant associations with PCAD (OR 1.62; 95% CI, 1.27-2.06; OR 1.65; 1.27-2.15).

CONCLUSIONS

Our investigation supported the fact that the ε2 allele in APOE may appear as a risk factor for PCAD in Asians while a protective factor in Caucasians and that the ε4 allele acted as a genetic risk factor for PCAD.

Genetic determinants of plasma lipoproteins

The search for common genetic determinants of plasma lipoproteins began in the early 1980s. Despite some exceptions, these efforts have not yet yielded a set of biological markers that can be used in clinical practice. By contrast, successes in defining the molecular basis of rare single-gene disorders, such as familial hypoalphalipoproteinemia, have shown the value of experimental designs that focus on genomic analysis of individuals within the tails of Gaussian distributions of quantitative lipoprotein traits. For example, this strategy showed that a small but relevant proportion of individuals within the <5% tail of plasma HDL-cholesterol distribution have mutations in genes that cause familial hypoalphalipoproteinemia. The value of clinical testing for genomic variants as an adjunct to a biochemical measurement of plasma lipoproteins, however, is at best questionable. A more direct impact of genetic studies is that definitions of 'common' and 'large genetic effects' have become more tempered, reflecting perhaps the biological reality that plasma lipoproteins are probably determined by the aggregate of numerous modest and occasional large genetic effects in addition to environmental factors. Here, we review recent progress on genomic variants and cholesterol metabolism, and discuss the impact these genetic studies will have on clinical cardiology.

The presence of apolipoprotein epsilon4 and epsilon2 alleles augments the risk of coronary artery disease in type 2 diabetic patients

OBJECTIVE

It has been suggested that there is a relationship between apolipoprotein E polymorphism and the severity of coronary artery disease in type II diabetes mellitus (T2DM). The current study specifically aimed to examine whether APOE polymorphism in association with serum lipids-lipoproteins level is a risk factor for developing coronary artery disease (CAD) in diabetic patients living in western of Iran.

METHODS

The APOE genotypes were detected by PCR-RFLP in 152 angiographically documented diabetic CAD patients, 262 non-diabetic (ND) individuals with CAD and 300 unrelated controls (normal coronary artery cases without diabetes) and serum lipid level was measured enzymatically.

RESULTS

The APOE-epsilon4 and epsilon2 allele frequencies were significantly higher in the CAD/T2DM and CAD/ND patients than in the control group (p<0.001). Our study demonstrated a significant association between APOE polymorphism and the level of plasma lipids with CAD/T2DM (p=0.001) and CAD/ND (p=0.026) patients. The CAD subjects with T2DM and ND patients carrying APOE-epsilon4 allele had lower plasma HDL-C level (p<0.001), (p=0.008) but had higher plasma LDL-C (p=0.01), total cholesterol (p=0.002), (p=0.03) and TG (p<0.001), (p=0.042) than that of the APOE-epsilon3 carriers, respectively. However, carriers of APOE-epsilon2 had significantly higher levels of plasma TG only. OR of APOE-epsilon4 and epsilon2 alleles in CAD/T2DM and CAD/ND patients were found to be 2.98 (p=0.001),1.86 (p=0.001), 2 (p=0.001), and 1.65 (p=0.001), respectively.

CONCLUSIONS

The major finding of the present case-control study is that T2DM patients carrying APOE-epsilon2 and epsilon4 alleles have a higher risk of developing CAD than ND patients in the western population of Iran, with APOE-epsilon4 being more closely associated with CAD than the APOE-epsilon2 allele. These results indicated that carriers of APOE-epsilon4 allele have a distinct plasma lipids profile and carrier of this allele with low levels of HDL-C and with high levels of LDL-C may be susceptible to CAD and myocardial infarction specially in diabetic patients. This suggests that a therapeutic modality should be considered for these patients.