Cholesteryl ester transfer protein (CETP) genotype and reduced CETP levels associated with decreased prevalence of hypertension

Association of CETP Gene Polymorphisms and Haplotypes with Acute Heart Rate Response to Exercise

Polymorphisms in the cholesteryl ester transfer protein (CETP) gene are known to be strongly associated with increased cardiovascular risk, primarily through their effects on the lipid profile and consequently on atherosclerotic risk. The acute heart rate response (AHRR) to physical activity is closely related to individual cardiovascular health. This study aimed to investigate the effect of CETP gene polymorphisms on AHRR. Our analysis examines the association of five single nucleotide polymorphisms (SNPs; rs1532624, rs5882, rs708272, rs7499892, and rs9989419) and their haplotypes (H) in the CETP gene with AHRR in 607 people from the Hungarian population. Individual AHRR in the present study was assessed using the YMCA 3-min step test and was estimated as the difference between resting and post-exercise heart rate, i.e., delta heart rate (ΔHR). To exclude the direct confounding effect of the CETP gene on the lipid profile, adjustments for TG and HDL-C levels, next to conventional risk factors, were applied in the statistical analyses. Among the examined five SNPs, two showed a significant association with lower ΔHR (rs1532624-Cdominant: B = -8.41, p < 0.001; rs708272-Gdominant: B = -8.33, p < 0.001) and reduced the risk of adverse AHRR (rs1532624-Cdominant: OR = 0.44, p = 0.004; rs708272-Gdominant: OR = 0.43, p = 0.003). Among the ten haplotypes, two showed significant association with lower ΔHR (H3-CAGCA: B = -6.81, p = 0.003; H9-CGGCG: B = -14.64, p = 0.015) and lower risk of adverse AHRR (H3-CAGCA: OR = 0.58, p = 0.040; H9-CGGCG: OR = 0.05, p = 0.009) compared to the reference haplotype (H1-AGACG). Our study is the first to report a significant association between CETP gene polymorphisms and AHRR. It also confirms that the association of the CETP gene with cardiovascular risk is mediated by changes in heart rate in response to physical activity, in addition to its effect on lipid profile.

Association of CETP Gene Polymorphisms and Haplotypes with Cardiovascular Risk

Cholesteryl ester transfer protein (CETP) is known to influence HDL-C levels, potentially altering the profile of HDL subfractions and consequently cardiovascular risk (CVR). This study aimed to investigate the effect of five single-nucleotide polymorphisms (SNPs; rs1532624, rs5882, rs708272, rs7499892, and rs9989419) and their haplotypes (H) in the CETP gene on 10-year CVR estimated by the Systematic Coronary Risk Evaluation (SCORE), the Framingham Risk Score for Coronary Heart Disease (FRSCHD) and Cardiovascular Disease (FRSCVD) algorithms. Adjusted linear and logistic regression analyses were used to investigate the association of SNPs and 10 haplotypes (H1-H10) on 368 samples from the Hungarian general and Roma populations. The T allele of rs7499892 showed a significant association with increased CVR estimated by FRS. H5, H7, and H8 showed a significant association with increased CVR based on at least one of the algorithms. The impact of H5 was due to its effect on TG and HDL-C levels, while H7 showed a significant association with FRSCHD and H8 with FRSCVD mediated by a mechanism affecting neither TG nor HDL-C levels. Our results suggest that polymorphisms in the CETP gene may have a significant effect on CVR and that this is not mediated exclusively by their effect on TG and HDL-C levels but also by presently unknown mechanisms.

Genetics of Cholesterol-Related Genes in Metabolic Syndrome: A Review of Current Evidence

Metabolic syndrome (MetS) refers to a cluster of metabolic dysregulations, which include insulin resistance, obesity, atherogenic dyslipidemia and hypertension. The complex pathogenesis of MetS encompasses the interplay between environmental and genetic factors. Environmental factors such as excessive nutrients and sedentary lifestyle are modifiable and could be improved by lifestyle modification. However, genetic susceptibility to MetS, a non-modifiable factor, has attracted the attention of researchers, which could act as the basis for future diagnosis, prognosis, and therapy for MetS. Several cholesterol-related genes associated with each characteristic of MetS have been identified, such as apolipoprotein, lipoprotein lipase (LPL), cholesteryl ester transfer protein (CETP) and adiponectin. This review aims to summarize the genetic information of cholesterol-related genes in MetS, which may potentially serve as biomarkers for early prevention and management of MetS.

Association of CETP Gene Variants with Atherogenic Dyslipidemia Among Thai Patients Treated with Statin

Objective

Patients treated with statins for dyslipidemia may still have a residual risk of atherosclerotic cardiovascular disease (ASCVD). To determine whether genetic variants in the cholesteryl ester transport protein (CETP), rs3764261 (C>A), rs708272 (G>A), and rs12149545 (G>A) affect ASCVD risk, we studied the association of these variants with dyslipidemia in statin-treated patients.

Patients and Methods

We included 299 adult Thai patients treated with a statin (95 men and 204 women). Genotyping was performed by conducting a TaqMan real-time polymerase chain reaction-based analysis. We used logistic regression models adjusted for potential confounders of age, body mass index, blood pressure, insulin resistance, and statin dosage to analyze the association between CETP variants and atherogenic lipoprotein patterns.

Results

CETP polymorphisms of rs3764261 and rs708272, but not rs12149545, were significantly associated with high-density lipoprotein cholesterol (HDL-C), apoA-I, triglycerides, very low-density lipoprotein (VLDL)-C, and large LDL (LDL1-C) levels as well as mean LDL particle size (all p < 0.020). However, no significant difference was observed in total cholesterol, LDL-C, or apoB levels by CETP variants. Regardless of sex, the combination of rs3764261 (CC genotype) and rs708272 (GG or GA genotypes) showed a stronger association with atherogenic dyslipidemia, including features of decreased HDL-C, elevated triglycerides, and LDL subclass pattern B (odds ratio [OR] = 2.99, 95% confidence interval [CI]: 1.78–5.02) compared with the single variant rs3764261 (OR = 2.11, 95% CI: 1.27–3.50) or rs708272 (OR = 2.12, 95% CI: 1.29–3.49).

Conclusion

The polymorphisms of CETP rs3764261 (CC genotype) and rs708272 (GG and GA genotypes) may have a higher susceptibility to atherogenic dyslipidemia. Testing for CETP rs3764261 and rs708272 may serve as a surrogate marker for lipid management in statin-treated patients, which may help individualize treatment for reducing the residual risk of ASCVD.

Metabolic fitness in relation to genetic variation and leukocyte DNA methylation

Metabolic syndrome (MetS) is a highly prevalent condition causing increased risk of several life-threatening diseases. MetS has a pronounced hereditary basis but is also influenced by environmental factors, partly through epigenetic mechanisms. In this study, the five phenotypes underlying MetS were incorporated into a continuous score for metabolic fitness (MF), and associations with both genotypic variation and leukocyte DNA methylation were investigated. Baseline MF phenotypes (waist circumference, blood pressure, blood glucose, serum triglycerides, and high-density lipoproteins) of 710 healthy Flemish adults were measured. After a 10 yr period, follow-up measures were derived from 618 of these subjects. Genotyping was performed for 65 preselected MF-related genetic variants. Next, full genetic predisposition scores (GPSs) were calculated, combining genotype scores of multiple genetic variants. Additionally, stepwise GPSs were constructed, including only the most predictive genetic variants for the different MF phenotypes. For a subset of 68 middle-aged men, global and gene-specific DNA methylation was investigated, and a biological pathway analysis was performed. The full GPSs were predictive for some baseline MF phenotypes, but not for changes over time. Only a limited number of genetic variants were significantly predictive individually. On the contrary, global and gene-specific DNA methylation was associated with changes in the MF phenotypes rather than with the baseline measures, indicating that effects of DNA methylation on MF are somewhat delayed. Furthermore, several biological pathways were associated with the MF phenotypes through gene promoter methylation. For CETP, G6PC2, MC4R, and TFAP2B both a genetic and epigenetic relationship was found with MF.

Informing Prevention and Intervention Policy Using Genetic Studies of Resistance

The common paradigm for conceptualizing the influence of genetic and environmental factors on a particular disease relies on the concept of risk. Consequently, the bulk of etiologic, including genetic, work focuses on "risk" factors. These factors are aggregated at the high end of the distribution of liability to disease, the latent variable underlying the distribution of probability and severity of a disorder. However, liability has a symmetric but distinct aspect to risk, resistance to disorder. Resistance factors, aggregated at the low end of the liability distribution and supporting health and recovery, appear to be more promising for effective prevention and intervention. Herein, we discuss existing work on resistance factors, highlighting those with known genetic influences. We examine the utility of incorporating resistance genetics in prevention and intervention trials and compare the statistical power of a series of ascertainment schemes to develop a general framework for examining resistance outcomes in genetically informative designs. We find that an approach that samples individuals discordant on measured liability, a low-risk design, is the most feasible design and yields power equivalent to or higher than commonly used designs for detecting resistance genetic and environmental effects.

Association between Six CETP Polymorphisms and Metabolic Syndrome in Uyghur Adults from Xinjiang, China

OBJECTIVE

To explore the association between CETP gene polymorphisms and metabolic syndrome (MS), as well as the relationship between the CETP gene polymorphisms and each component of MS.

METHODS

A total of 571 individuals which were randomly selected from 5692 Uyghur adults were subdivided into two groups, including 280 patients with MS and 291 control subjects, using the group-matching method after matching for gender. We detected CETP polymorphisms (rs5882, rs1800775, rs3764261, rs12149545, rs711752, and rs708272) by using the Snapshot method.

RESULTS

(1) Significant differences were found involving the frequency distribution of genotypes and alleles of rs1800775, rs3764261, rs12149545, rs711752, and rs708272 between the control and MS groups (all p < 0.05). (2) rs1800775, rs3764261, rs12149545, rs711752, and rs708272 polymorphisms were significantly related to the risk of MS (all p < 0.05). (3) The rs1800775 polymorphism was associated with high fasting blood glucose levels and low high density lipoprotein cholesterol (HDL-C); rs3764261 and rs12149545 polymorphisms were associated with all components of MS except high blood pressure; rs711752 and rs708272 polymorphisms were associated with low HDL-C (all p < 0.05). (4) Complete linkage disequilibrium (LD) was identified for two pairs of single nucleotide polymorphisms (SNPs) (rs3764261 and rs12149545 (D' = 1.000, r² = 0.931), rs711752 and rs708272 (D' = 1.000, r² = 0.996)). (5) The A-G-G-G-C (p = 0.013, odds ratio [OR] = 0.622, 95% confidence interval [95% CI] = 0.427-0.906) and A-T-A-A-T (p < 0.001, OR = 0.519, 95% CI = 0.386-0.697) haplotypes were more frequent in the control group than in the case group. Conclusions: The rs1800775, rs3764261, rs12149545, rs711752, and rs708272 polymorphisms of CETP were associated with MS and its components among the Uyghur ethnic group. Complete LD was found between two pairs of SNPs (rs3764261 and rs12149545, rs711752, and rs708272). The A-G-G-G-C and A-T-A-A-T haplotypes might be protective factors for MS.

Association of the CETP gene TaqIB and D442G polymorphisms with essential hypertension in the Chinese Mongolian population

BACKGROUND/AIM

This study aimed to explore the associations of the cholesteryl ester transfer protein (CETP) gene TaqIB and D442G polymorphisms with essential hypertension (EH).

MATERIALS AND METHODS

In this case-control study, 883 hypertensive patients and 1044 normal controls were randomly selected from the Mongolian population of China. Polymerase chain reaction (PCR) and direct sequencing of PCR products were used to identify the genotypes. Haplotype analysis was performed by estimating the haplotype frequencies using the online SHEsis package.

RESULTS

The distribution frequency of the B2-G haplotype was significantly lower in the EH group than in the control group (0.7% vs. 1.9%, P = 0.001, OR = 0.359 [0.188-0.689]). Subjects with the B2B2 genotype showed significantly lower levels of total cholesterol (TC) (P < 0.05). When subgrouped by sex, male subjects with the B2B2 genotype showed significantly increased high-density lipoprotein cholesterol and decreased TC levels (P < 0.05), and those with the B2 allele showed significantly lower triglyceride levels as compared to the subjects with the B1B1 homozygote (P < 0.05).

CONCLUSION

TaqIB and D442G polymorphisms of the CETP gene did not independently affect the risk of developing EH in the Chinese Mongolian population, while the B2-G haplotype obviously decreased the susceptibility to EH. The B2 allele could alter the blood lipid level and reduce the risk of developing cardiovascular diseases.

Genome-Wide Scan Informed by Age-Related Disease Identifies Loci for Exceptional Human Longevity

We developed a new statistical framework to find genetic variants associated with extreme longevity. The method, informed GWAS (iGWAS), takes advantage of knowledge from large studies of age-related disease in order to narrow the search for SNPs associated with longevity. To gain support for our approach, we first show there is an overlap between loci involved in disease and loci associated with extreme longevity. These results indicate that several disease variants may be depleted in centenarians versus the general population. Next, we used iGWAS to harness information from 14 meta-analyses of disease and trait GWAS to identify longevity loci in two studies of long-lived humans. In a standard GWAS analysis, only one locus in these studies is significant (APOE/TOMM40) when controlling the false discovery rate (FDR) at 10%. With iGWAS, we identify eight genetic loci to associate significantly with exceptional human longevity at FDR < 10%. We followed up the eight lead SNPs in independent cohorts, and found replication evidence of four loci and suggestive evidence for one more with exceptional longevity. The loci that replicated (FDR < 5%) included APOE/TOMM40 (associated with Alzheimer’s disease), CDKN2B/ANRIL (implicated in the regulation of cellular senescence), ABO (tags the O blood group), and SH2B3/ATXN2 (a signaling gene that extends lifespan in Drosophila and a gene involved in neurological disease). Our results implicate new loci in longevity and reveal a genetic overlap between longevity and age-related diseases and traits, including coronary artery disease and Alzheimer’s disease. iGWAS provides a new analytical strategy for uncovering SNPs that influence extreme longevity, and can be applied more broadly to boost power in other studies of complex phenotypes.

Longevity is a complex phenotype, and few genetic variants that affect lifespan have been identified. However, aging and disease are closely related, and a great deal is known about the genetic basis of disease risk. Here, we show using genome-wide association studies (GWAS) of longevity and disease that there is an overlap between loci involved in longevity and loci involved in several diseases, such as Alzheimer’s disease and coronary artery disease. We then develop a new statistical framework to find genetic variants associated with extreme longevity. The method, informed GWAS (iGWAS), takes advantage of knowledge from 14 large studies of disease and disease-related traits in order to narrow the search for SNPs associated with longevity. Using iGWAS, we found eight SNPs that are significant in our discovery cohorts, and we were able to validate four of these in replication studies of long-lived subjects. Our results implicate new loci in longevity and reveal a genetic overlap between longevity and age-related diseases and traits. Beyond the study of human longevity, iGWAS can be applied to boost statistical power in any GWAS of a target phenotype by using larger GWAS of genetically-related conditions.

Exceptional longevity is associated with decreased reproduction

A number of leading theories of aging, namely The Antagonistic Pleiotropy Theory (Williams, 1957), The Disposable Soma Theory (Kirkwood, 1977) and most recently The Reproductive-Cell Cycle Theory (Bowen and Atwood, 2004, 2010) suggest a tradeoff between longevity and reproduction. While there has been an abundance of data linking longevity with reduced fertility in lower life forms, human data have been conflicting. We assessed this tradeoff in a cohort of genetically and socially homogenous Ashkenazi Jewish centenarians (average age ~100 years). As compared with an Ashkenazi cohort without exceptional longevity, our centenarians had fewer children (2.01 vs 2.53, p<0.0001), were older at first childbirth (28.0 vs 25.6, p<0.0001), and at last childbirth (32.4 vs 30.3, p<0.0001). The smaller number of children was observed for male and female centenarians alike. The lower number of children in both genders together with the pattern of delayed reproductive maturity is suggestive of constitutional factors that might enhance human life span at the expense of reduced reproductive ability.