Relation of polymorphisms in the cholesteryl ester transfer protein gene to transfer protein activity and plasma lipoprotein levels in alcohol drinkers

Dietary antioxidant status indices may not interact with CETP Taq1B polymorphism on lipid profile and severity of coronary artery stenosis in patients under coronary angiography

The association of CETP Taq1B polymorphism with some metabolic traits is still controversial. The interaction of adherence to dietary indices with this polymorphism on the severity of coronary artery stenosis and serum lipid parameters needs to be investigated. This study aimed to test this hypothesis. This cross-sectional study included 453 patients who were referred from Afshar Hospital of Yazd and undergoing coronary angiography from 2020 to 2021. Dietary intake was evaluated by a 178-item validated and reliable dietary questionnaire. Dietary indices such as dietary antioxidant index (DAI), dietary antioxidant quality score (DAQS), and dietary phytochemical index (DPI) are determined according to dietary guidelines. The Taq1B variant was genotyped by the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP). Two-way ANOVA was used to test the interaction between Taq1B polymorphism and dietary indices. The results of the frequency analysis of Taq1B genotypes showed that 10.4% were B1B1, 72.4% B1B2, and 17.2% B2B2. No significant interaction was found between the Taq1B variant with high adherence to DAQS, DAI, and DPI on total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), triglyceride (TG) levels, and Gensini score (GS) and Syntax score (SS). In high-adherence dietary indices, lipid profile and coronary artery stenosis scores did not differ significantly in Taq1B genotypes. Due to the insignificant results in this research, further studies are needed to investigate the role of Taq1B SNP in modulating dyslipidemia and the severity of the CAD in interaction with dietary indices.

Gender Differences in the Association between Cholesteryl Esters Transfer Protein Polymorphism (rs708272) and Plasma Lipid Levels in Hyperlipidaemic Participants at Hospital Universiti Sains Malaysia

Background

Single nucleotide polymorphism (SNP) in the cholesteryl esters transfer protein (CETP) gene (rs708272) was reported to affect statin efficacy. This study investigated the association between CETP rs708272 and statin's lipid-lowering effects in hyperlipidaemic participants at Hospital Universiti Sains Malaysia, Kelantan.

Methods

A total of 229 hyperlipidaemic statin users (96.1% Malays) were recruited, and a single blood sample (3 mL) was obtained for DNA extraction. The genotypes were determined using PCR-RFLP method and validated by sequencing analysis.

Results

The minor allele frequency for rs708272 in all participants was 0.391, with no difference between females and males. At the baseline, the SNP was associated with different low-density lipoprotein (LDL-c) and triglyceride (TG) levels in females, but not males, when the GG and GA+AA genotypes were compared using a dominant genetic model. Regardless of the genotype, the total cholesterol and LDL-c levels decreased significantly (P < 0.001) in both genders after statin treatment, but the TG levels decreased exclusively in females with the GG genotypes. In both genders, high density lipoprotein levels were unaffected before and after the statin treatment.

Conclusion

To improve the management of hyperlipidaemia, future research should consider patient gender when assessing the CETP rs708272 impact on LDL-c and TG.

A Nutrigenetic Update on CETP Gene–Diet Interactions on Lipid-Related Outcomes

Purpose of Review

An abnormal lipid profile is considered a main risk factor for cardiovascular diseases and evidence suggests that single nucleotide polymorphisms (SNPs) in the cholesteryl ester transfer protein (CETP) gene contribute to variations in lipid levels in response to dietary intake. The objective of this review was to identify and discuss nutrigenetic studies assessing the interactions between CETP SNPs and dietary factors on blood lipids.

Recent Findings

Relevant articles were obtained through a literature search of PubMed and Google Scholar through to July 2021. An article was included if it examined an interaction between CETP SNPs and dietary factors on blood lipids. From 49 eligible nutrigenetic studies, 27 studies reported significant interactions between 8 CETP SNPs and 17 dietary factors on blood lipids in 18 ethnicities. The discrepancies in the study findings could be attributed to genetic heterogeneity, and differences in sample size, study design, lifestyle and measurement of dietary intake. The most extensively studied ethnicities were those of Caucasian populations and majority of the studies reported an interaction with dietary fat intake. The rs708272 (TaqIB) was the most widely studied CETP SNP, where ‘B1’ allele was associated with higher CETP activity, resulting in lower high-density lipoprotein cholesterol and higher serum triglycerides under the influence of high dietary fat intake.

Summary

Overall, the findings suggest that CETP SNPs might alter blood lipid profiles by modifying responses to diet, but further large studies in multiple ethnic groups are warranted to identify individuals at risk of adverse lipid response to diet.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11883-022-00987-y.

Cholesteryl ester transfer protein and its inhibitors

Most of the cholesterol in plasma is in an esterified form that is generated in potentially cardioprotective HDLs. Cholesteryl ester transfer protein (CETP) mediates bidirectional transfers of cholesteryl esters (CEs) and triglycerides (TGs) between plasma lipoproteins. Because CE originates in HDLs and TG enters the plasma as a component of VLDLs, activity of CETP results in a net mass transfer of CE from HDLs to VLDLs and LDLs, and of TG from VLDLs to LDLs and HDLs. As inhibition of CETP activity increases the concentration of HDL-cholesterol and decreases the concentration of VLDL- and LDL-cholesterol, it has the potential to reduce atherosclerotic CVD. This has led to the development of anti-CETP neutralizing monoclonal antibodies, vaccines, and antisense oligonucleotides. Small molecule inhibitors of CETP have also been developed and four of them have been studied in large scale cardiovascular clinical outcome trials. This review describes the structure of CETP and its mechanism of action. Details of its regulation and nonlipid transporting functions are discussed, and the results of the large scale clinical outcome trials of small molecule CETP inhibitors are summarized.

Association of Cholesteryl Ester Transfer Protein and Endothelial Nitric Oxide Synthase Gene Polymorphisms With Coronary Artery Disease in the Multi-Ethnic Malaysian Population

Genetic variants of cholesteryl ester transfer protein (CETP) and endothelial nitric oxide synthase (eNOS) influence high-density lipoprotein cholesterol (HDL-C) metabolism and nitric oxide (NO) synthesis, respectively, and might increase the risk of coronary artery disease (CAD). This study is to investigate the relationship between genetic polymorphisms and the risk of CAD and to evaluate their potential interactions. A total of 237 patients with CAD and 101 controls were genotyped. The association of the polymorphism with the risk of CAD varied among the ethnic groups. Moreover, the concomitant presence of both CETP B1 and eNOS 4a alleles significantly increased the risk of CAD in the Malay group (OR = 33.8, P < .001) and the Indian group (OR = 10.9, P = .031) but not in the Chinese group. This study has identified a novel ethnic-specific gene–gene interaction and suggested that the combination of CETP B1 allele and eNOS 4a allele significantly increases the risk of CAD in Malays and Indians.

Meta-analysis of cholesteryl ester transfer protein TaqIB polymorphism and risk of myocardial infarction

A number of studies have been conducted to explore the association between the cholesteryl ester transfer protein (CETP) TaqIB polymorphism and risk of myocardial infarction (MI); however, the results are inconsistent. Therefore, we conducted this meta-analysis to clarify the issue based on all the data available.Eligible studies were retrieved by searching PubMed, Embase, Web of Science, and Google Scholar. We calculated the crude odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs) to assess the association between the TaqIB polymorphism and risk of MI.We included 13 studies involving 8733 MI cases and 8573 controls in the meta-analysis. The pooled results from all included studies showed decreased MI risk in the analysis of the B2B2 versus B1B1 (OR = 0.78, 95% CI = 0.68-0.91), dominant (OR = 0.88, 95% CI = 0.77-0.99), and recessive genetic models (OR = 0.84, 95% CI = 0.78-0.91). The frequency of the B2B2 genotype in MI patients was lower (OR = 0.87, 95% CI = 0.81-0.94). However, there was no significant association in the B1B2 versus B1B1 analysis (OR = 0.92, 95% CI = 0.81-1.05) and no significant difference for the B1B1 genotype (OR = 1.04, 95% CI = 0.98-1.11) and B1B2 genotype (OR = 1.03, 95% CI = 0.97-1.08). Cumulative analysis confirmed these results.Our results suggest that the B2B2 genotype of the CETP TaqIB polymorphism is a protective factor against the development of MI.

Resistance and intolerance to statins

BACKGROUND AND AIMS

Many patients treated with statins are considered statin-resistant because they fail to achieve adequate reduction of low density lipoprotein cholesterol (LDL-C) levels. Some patients are statin-intolerant because they are unable to tolerate statin therapy at all or to tolerate a full therapeutic statin dose because of adverse effects, particularly myopathy and increased activity of liver enzymes.

RESULTS

The resistance to statins has been associated with polymorphisms in the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA-R), P-glycoprotein (Pg-P/ABCB1), breast cancer resistance protein (BCRP/ABCG2), multidrug resistance-associated proteins (MRP1/ABCC1 and MRP2/ABCC2), organic anion transporting polypeptides (OATP), RHOA, Nieman-Pick C1-like1 protein (NPC1L1), farnesoid X receptor (FXR), cholesterol 7alpha-hydroxylase (CYP7A1), Apolipoprotein E (ApoE), proprotein convertase subtilisin/kexin type 9 (PCSK9), low density lipoprotein receptor (LDLR), lipoprotein (a) (LPA), cholesteryl ester transfer protein (CETP), and tumor necrosis factor α (TNF-α) genes. However, currently, there is still not enough evidence to advocate pharmacogenetic testing before initiating statin therapy. Patients with inflammatory states and HIV infection also have diminished LDL-C lowering as a response to statin treatment. Pseudo-resistance due to nonadherence or non-persistence in real-life circumstances is probably the main cause of insufficient LDL-C response to statin treatment.

CONCLUSIONS

If a patient is really statin-resistant or statin-intolerant, several other treatment possibilities are nowadays available: ezetimibe alone or in combination with bile acid sequestrants, and possibly in the near future mipomersen, lomitapide, or monoclonal antibodies against PCSK9.

Common variants of apolipoprotein E and cholesteryl ester transport protein genes in male patients with coronary heart disease and variable body mass index

Plasma lipids are major risk factors for coronary heart disease (CHD). Cholesteryl ester transfer protein (CETP) and apolipoprotein (apo) E genes are involved in lipoprotein metabolism, thus affecting plasma lipid and lipoproteins levels. Furthermore, such polymorphisms have been associated with susceptibility to CHD and obesity. We evaluated the influence of the gene polymorphisms of CETP TaqIB (B1, B2) and I405V (V, I) and apo E (∊2,∊3,∊4) on lipid levels, according to body mass index (BMI) in Greek men with CHD. The TaqIB (B1, B2) polymorphism affected plasma low-density lipoprotein cholesterol levels in overweight men with CHD, whereas the I405V (V, I) polymorphism affected triglyceride concentrations in normal weight men. No correlation was found between BMI and apo E polymorphisms. Large prospective studies are required to investigate the relationships of CETP and apo E polymorphisms with lipids, BMI, and CHD susceptibility.

The roles of genetic polymorphisms and human immunodeficiency virus infection in lipid metabolism

Dyslipidemia has been frequently observed among individuals infected with human immunodeficiency virus type 1 (HIV-1), and factors related to HIV-1, the host, and antiretroviral therapy (ART) are involved in this phenomenon. This study reviews the roles of genetic polymorphisms, HIV-1 infection, and highly active antiretroviral therapy (HAART) in lipid metabolism. Lipid abnormalities can vary according to the HAART regimen, such as those with protease inhibitors (PIs). However, genetic factors may also be involved in dyslipidemia because not all patients receiving the same HAART regimen and with comparable demographic, virological, and immunological characteristics develop variations in the lipid profile. Polymorphisms in a large number of genes are involved in the synthesis of structural proteins, and enzymes related to lipid metabolism account for variations in the lipid profile of each individual. As some genetic polymorphisms may cause dyslipidemia, these allele variants should be investigated in HIV-1-infected patients to identify individuals with an increased risk of developing dyslipidemia during treatment with HAART, particularly during therapy with PIs. This knowledge may guide individualized treatment decisions and lead to the development of new therapeutic targets for the treatment of dyslipidemia in these patients.

Association of CETP Taq1B and -629C > A polymorphisms with coronary artery disease and lipid levels in the multi-ethnic Singaporean population

BACKGROUND

Hyperlipidaemia is a major risk factor for coronary artery disease (CAD) and cholesteryl ester transfer protein (CETP) gene polymorphisms are known to be associated with lipid profiles.

METHODS

In this study, we investigated the association of two polymorphisms in the CETP, Taq1B (rs708272) and -629C > A (rs1800775), with CAD and lipid levels HDL-C in 662 CAD + cases and 927 controls from the Singapore population comprising Chinese, Malays and Indians.

RESULTS

TaqB2 frequency was significantly lowest in the Malays (0.43) followed by Chinese (0.47) and highest in the Indians (0.56) in the controls. The B2 allele frequency was significantly lower in the Chinese CAD + cases compared to the controls (p = 0.002). The absence of the B2 allele was associated with CAD with an OR 2.0 (95% CI 1.2 to 3.4) after adjustment for the confounding effects of age, smoking, BMI, gender, hypertension, dyslipidemia and diabetes mellitus. The B2 allele was significantly associated with higher plasma HDL-C levels in the Chinese men after adjusting for confounders. Associations with plasma apoA1 levels were significant only in the Chinese men for Taq1B and -629C > A. In addition, the Taq1B polymorphism was only associated with plasma Apo B and Lp(a) in the Malay men. Significant associations were only found in non-smoking subjects with BMI <50th percentile. In this study, the LD coefficients between the Taq1B and -629C > A polymorphisms seemed to be weak.

CONCLUSION

The absence the Taq1B2 allele was associated with CAD in the Chinese population only and the minor allele of the Taq1B polymorphism of the CETP gene was significantly associated with higher plasma HDL-C levels in Chinese men.

Cholesteryl ester transfer protein gene and effectiveness of lipid lowering of atorvastatin

Cholesteryl ester transfer protein (CETP) plays a key role in lipid metabolism. Thus, variations in the CETP gene may be clinically relevant. Newly started atorvastatin users (n=212) were genotyped for CETP genetic variants (TaqIB and I405V). Homozygotes for B1 allele of TaqIB polymorphism had lower plasma high density lipoprotein cholesterol (HDL-C) compared with B1B2 or B2B2 genotypes (p=0.03, for each). Homozygotes for I allele of I405V polymorphism had lower plasma HDL-C compared with IV or VV genotypes (p=0.001, for each). In the whole population, the B1 carriers increased HDL-C levels by 4% after atorvastatin treatment, compared with B2 carriers, where a 4% decrease occurred (p=0.03). Also homozygotes for B1 allele decreased triglyceride levels to a lesser, though not significant, degree compared to B1B2 or B2B2 genotypes. CETP TaqIB or I405V polymorphisms seem to modify the lipid lowering response to atorvastatin treatment. This knowledge may help design more effective hypolipidaemic treatment.

Association between CETP Taq1B and LIPC -514C/T polymorphisms with the serum lipid levels in a group of Tehran's population: a cross sectional study

BACKGROUND

Low level of high density lipoprotein cholesterol (HDL-C) has high prevalence in the Tehran Lipid and Glucose Study (TLGS) cohort. About 50% of the inter-individual variation in serum HDL-C levels is genetically determined. Polymorphisms in cholesteryl ester transfer protein (CETP) and hepatic lipase (LIPC) genes have been found to be associated with the metabolism and serum concentration of the HDL-C.

OBJECTIVES

To determine the association between Taq1B polymorphism in CETP gene and -514C/T polymorphism in LIPC gene with serum lipid levels and lipid peroxidation in a subgroup of the TLGS population.

RESULTS

Serum HDL-C level had significant association with CETP Taq1B polymorphism and B2B2 subjects had the highest HDL-C levels compared to B2B1 and B1B1 genotypes (37.9 vs. 36.9 and 35.3 mg/dl, respectively; P = 0.01). However, carriers of "B1" allele, in comparison to the non carriers (B2B2), had significantly lower levels of TC (200.1 vs. 215.2 mg/dl; P = 0.005), HDL-C (35.8 vs. 37.9 mg/dl; P = 0.009) and malondialdehyde MDA (4.5 vs. 5.0 nmol/mL; P=0.031). Carriers of the "T" allele in -514C/T polymorphism in LIPC gene had higher means of HDL-C than non carriers (37.7 vs. 35.7 mg/dl, P = 0.04). No other association was found between -514C/T polymorphism and any other serum lipids or MDA level.

CONCLUSION

This study demonstrates the association between Taq1B and -514C/T polymorphisms in the CETP and LIPC genes with the serum HDL-C levels.

Genetic variants at the APOE, lipoprotein lipase (LpL), cholesteryl ester transfer protein (CETP), and endothelial nitric oxide (eNOS) genes and coronary artery disease (CAD): CETP Taq1 B2B2 associates with lower risk of CAD in Asian Indians

Coronary artery disease (CAD) arises due to a complex interplay between the environment and genetic factors. Alterations in many of the biomarkers such as lipids and lipoprotein levels are characteristic of CAD. The phenotypes themselves have genetic determinants, and many single-nucleotide polymorphisms (SNPs) have been identified which influence them. The current study aims to evaluate the effect of six common polymorphisms at four loci, lipoprotein lipase (D9N, N291S, S447X), apolipoprotein E (APOE), cholesteryl ester transfer protein (C277T), and endothelial nitric oxide synthase (E298D), on lipid and lipoprotein levels and its association with CAD. Genotyping for the SNPs was done in 240 Indians of which 90 had proven CAD. The other 150 were clinically free from CAD and acted as controls. Relation of genetic variants, clinical history, and biochemical parameters with CAD were analyzed by multiple regression analysis. The frequency of the B2 allele in the CETP gene was significantly lower in cases than in controls (0.40 vs 0.49, P = 0.042). Significant association of CETP Taq1B SNP was seen with total cholesterol and low density lipoprotein cholesterol. Multivariate analysis accounting for clinical and metabolic predictors of CAD showed smoking to be a significant risk factor (odds ratio (OR) 4.347, 95% confidence interval (CI) 1.888-10.012, P = 0.001) and the CETP B2 variant imparting atheroprotection (OR 0.312, 95% CI 0.116-0.841, P = 0.021) possibly through a favorable lipid profile. None of the other SNPs were associated with the risk of CAD.

Association of two CETP polymorphisms with HDL levels in the Chinese obese population

The association of two cholesterol ester transfer protein (CETP) polymorphisms, D442G and TAQIB (B1-->B2), with high-density lipoprotein (HDL) levels in 932 Chinese obese individuals (BMI >or= 27) was investigated in comparison with normal controls (BMI <or= 24). Independent association was demonstrated for TAQIB minor allele B2 and CETP442 minor allele G with elevated HDL levels. The CETP D442G polymorphism was associated with a much greater increase in HDL levels in subjects with BMI exceeding 27 kg/m(2) (+5.42 mg/dl, P = 0.0007) compared to normal controls (+1.97 mg/dl, P = 0.275), and the increase in HDL reached the highest level among subjects with BMI exceeding 30 kg/m(2) (+6.80 mg/dl, P = 0.016). TAQIB showed significant association with HDL levels only in normal BMI subgroup (P = 0.0017). TAQIB significantly interacted with serum triglyceride (TG) on modulating HDL levels (P = 0.027). The TAQIB-TG interaction effect remained marginally significant after controlling for BMI (P = 0.057). We conclude that D442G polymorphism is associated with more HDL elevation in obesity. TAQIB interacts with serum TG on modulating HDL levels, and the interaction is partly independent of BMI.

Genetic determinants of response to statins

In developed countries, cardiovascular disease is one of the leading causes of death. Statins are abundantly prescribed to reduce the risk of coronary artery disease by lowering cholesterol. Genetic factors are thought to be partly responsible for the interindividual variation in the response to statins. This article reviews the most important studies conducted on pharmacogenetics of statins. Currently, there is no evidence to advocate pharmacogenetic testing before initiating therapy.

Lack of association between the cholesteryl ester transfer protein gene--TaqIB polymorphism and coronary restenosis following percutaneous transluminal coronary angioplasty and stenting: a pilot study

BACKGROUND

The most widely studied variation at the cholesteryl ester transfer protein (CETP) gene locus is a silent base change called the Thermobius aquaticus IB (TaqIB) polymorphism. TaqIB has been shown to affect levels/activity of CETP, plasma levels of high-density lipoprotein cholesterol (HDL-C), and to contribute to the risk of developing atherosclerosis and coronary heart disease (CHD). Ongoing studies are investigating possible associations between CETP gene polymorphisms and the development of coronary restenosis following percutaneous transluminal coronary angioplasty (PTCA) and stenting.

METHODS AND RESULTS

The primary objective of the present study was to investigate the frequency of TaqIB-polymorphism, and a possible association with post-PTCA coronary restenosis, in 204 Greek patients who had undergone PTCA and stenting. As a secondary objective, the analysis was extended to explore possible interacting or additive effects by various CHD risk factors, and a deletion in the alpha(2B)-adrenergic receptor gene. The frequency of TaqIB was 54%, similar to the frequency of the polymorphism in a group of 35 healthy controls.

CONCLUSIONS

The results from this study do not indicate that the TaqIB variation at the CETP gene locus is a significant predictor for assessing the risk of developing coronary restenosis following PTCA and stenting. This result was not affected when considering any one of the additionally studied factors.

Cholesteryl ester transfer protein (CETP) inhibitors: is there life after torcetrapib?

Despite tremendous progress made in the management of CHD, a significant number of fatal and nonfatal CHD events still occur, which leads researchers to target other modifiable risk factors for CHD including low HDL-c (high density lipoprotein cholesterol). Although the torcetrapib experience was a major blow to CETP inhibition and indeed to the entire field of HDL-targeted therapeutics, it was not fatal. The off-target effects of torcetrapib appear to be substantial and may have overridden any potential cardiovascular benefit. Despite continued uncertainty regarding the cardiovascular implications of genetic CETP deficiency and pharmacologic CETP inhibition, there remain reasons to believe in the mechanism and the possibility that clean CETP inhibitors will not only improve plasma lipids but also reduce cardiovascular risk.

Cholesteryl ester transfer protein TaqIB, -629C>A and I405V polymorphisms and risk of coronary heart disease in an Indian population

BACKGROUND

Polymorphisms in cholesteryl ester protein gene have been linked to risk of coronary heart disease (CHD) in many world populations through their effect on reverse cholesterol transport.

METHODS

Five hundred four (504) unrelated electrocardiograph confirmed cases of CHD and 338 population based controls, matched by age and gender, belonging to the Tamilian population of south India were genotyped for polymorphisms in CETP gene using PCR RFLP methods.

RESULTS

The multivariate logistic regression analyses demonstrated that CETP B1B1 and CA genotypes of TaqIB and -629C>A were significantly associated with increased risk for CHD (odds ratio (OR) 2.7; 95% confidence intervals (CI) (1.5-3.3); OR 1.5 (1.1-2.4)) respectively. Combined wild genotypes of CETP gene showed an association with CHD (OR-1.7 (1.0-2.9) as well as the combined heterozygous mutants (OR 1.5 (1.0-2.3); p-0.03). Subgroup analysis based on gender revealed that men harboring CETP B1B1 and CA genotypes have a significant risk for CHD B1B1- 2.7 (1.7-4.3), CA-1.8 (1.3-2.6). There was no link between CETP I450V polymorphism and CHD. Analysis based on hypertensive status showed a significant association between these polymorphisms and non hypertensive CHD patients.

CONCLUSIONS

The risk in non hypertensive and male CHD patients is higher in the presence of CETP B1B1 and CA genotypes.

Impact of genetic polymorphisms on the efficacy of HMG-CoA reductase inhibitors

Although pharmacologic treatment for cholesterol reduction represents an advance in cardiovascular and atherosclerosis treatment, the benefits of such therapy are still limited because of interindividual variability in the response to these drugs. Disease severity, treatment adherence, physiologic conditions, biologic conditions, and the patient's genetic profile could be cited as important factors in the evaluation of interindividual variability. In regard to the latter consideration, three large groups of genes could be investigated: (i) genes that code for proteins involved in metabolism and/or drug transport, thereby influencing the pharmacokinetics of these compounds; (ii) genes that code for proteins involved in the mechanism of action and/or in the metabolic pathway of drug action, and which therefore influence pharmacodynamics; and (iii) genes that code for proteins involved in direct development of the disease or in intermediate phenotypes. In this review we discuss pharmacogenetic studies of the HMG-CoA reductase inhibitors (statins) and the implications of pharmacogenetic considerations for predicting treatment efficacy and reducing the adverse effects of these drugs. Once new studies have been performed and most of the genetic variability associated with drug action has been revealed, the great challenge will be to apply this knowledge in clinical medicine.

Interactions between alcohol intake and the polymorphism of rs708272 on serum high-density lipoprotein cholesterol levels in the Guangxi Hei Yi Zhuang population

Both alcohol consumption and the polymorphism of the cholesteryl ester transfer protein (CETP) TaqIB gene (rs708272) influence plasma high-density lipoprotein cholesterol (HDL-C) levels. However, their interactions on serum HDL-C levels is not well known. The present study was undertaken to detect the interactions between alcohol consumption and the rs708272 polymorphism on serum lipid levels in the Guangxi Hei Yi Zhuang population. Genotyping of the rs708272 in 342 nondrinkers and 416 drinkers aged 15-70 years was performed by polymerase chain reaction and restriction fragment length polymorphism. Interactions between rs708272 genotype and alcohol consumption was assessed using a cross-product term between genotypes and the aforementioned factor. Statistical significance was evaluated with analysis of co-variance. The frequency of B1 allele was 65.8% in nondrinkers and 64.7% in drinkers (P>.05), respectively. The frequencies of B1B1, B1B2, and B2B2 genotypes were 45.0%, 41.5%, and 13.5% in nondrinkers, and 41.3%, 46.6%, and 12.0% in drinkers (P>.05), respectively. The levels of HDL-C and apolipoprotein (Apo) AI in nondrinkers were higher in B2B2 genotype than in B1B1 genotype (P<.05 for each), whereas triglyceride (TG) levels in drinkers were higher in B1B1 genotype than in B1B2 genotype (P<.05). The levels of TG, HDL-C, Apo AI in B1B1 genotype, and HDL-C and Apo AI in B1B2 genotype were higher in drinkers than in nondrinkers (P<.05-.01), whereas the levels of low-density lipoprotein cholesterol (LDL-C) and Apo B in B2B2 genotype, and the levels of LDL-C in B1B1 genotype were lower in drinkers than in nondrinkers (P<.05-.01). The levels of HDL-C were positively correlated with female sex and genotype in nondrinkers (P<.001 for each), and were positively associated with age and alcohol consumption in drinkers (P<.005 and<.01, respectively). This study suggests that the B1 carriers benefited more from alcohol consumption than the B2 carriers in increasing serum HDL-C and Apo AI levels, and lowering LDL-C levels.

Why study gene-environment interactions?

PURPOSE OF REVIEW

We examine the reasons for investigating gene-environment interactions and address recent reports evaluating interactions between genes and environmental modulators in relation to cardiovascular disease and its common risk factors.

RECENT FINDINGS

Studies focusing on smoking, physical activity, and alcohol and coffee consumption are observational and include relatively large sample sizes. They tend to examine single genes, however, and fail to address interactions with other genes and other correlated environmental factors. Studies examining gene-diet interactions include both observational and interventional designs. These studies are smaller, especially those including dietary interventions. Among the reported gene-diet interactions, it is important to highlight the strengthened position of APOA5 as a major gene that is involved in triglyceride metabolism and modulated by dietary factors, and the identification of APOA2 as a modulator of food intake and obesity risk.

SUMMARY

The study of gene-environment interactions is an active and much needed area of research. Although technical barriers of genetic studies are rapidly being overcome, inclusion of comprehensive and reliable environmental information represents a significant shortcoming of genetics studies. Progress in this area requires inclusion of larger populations but also more comprehensive, standardized, and precise approaches to capturing environmental information.

Inconsistencies in the genetic prediction of HDL cholesterol versus atherosclerosis

PURPOSE OF REVIEW

High-density lipoprotein (HDL) is generally perceived as having a protective role with respect to cardiovascular disease. The metabolism of HDL is mediated through a complex network of apoproteins, enzymes and transfer proteins. Genetic variants within this network can increase plasma HDL, but not with uniformly beneficial clinical outcomes. The purpose of this review is to explore and propose mechanisms for these discrepant observations.

RECENT FINDINGS

Recent developments in this area include new observations of genetic variants that paradoxically increase both HDL and cardiovascular risk. Also discussed are newly observed, function-altering modifications of the HDL particle. Proposed explanations include the segregation of the genetic variants associated with the respective endpoints of plasma HDL and cardiovascular risk. Functionally impaired but quantitatively robust plasma HDL and the emerging understanding of proinflammatory HDL also may contribute to our understanding of discordant observations.

SUMMARY

Enhanced understanding of these relationships may allow a more accurate assessment of clinical risk based on plasma HDL and help explain why HDL may, in some circumstances, be an inappropriate therapeutic target.

Cholesteryl ester transfer protein B1B1 genotype is associated with a parental history of cardiovascular diseases in Taiwanese people

OBJECTIVE

To investigate the association between family history of cardiovascular disease (CVD) and cholesteryl ester transfer protein (CETP) TaqIB polymorphism in Taiwanese subjects.

SUBJECTS AND METHODS

In this cross-sectional study, 240 subjects (115 men and 125 women) were divided into two groups based on whether or not they had a parental history of CVD. Polymerase chain reaction/restriction fragment length polymorphism was used to analyze the genotype of the subjects for the TaqIB polymorphism of CETP in intron 1.

RESULTS

The frequency of the B1B1 genotype was significantly higher in Taiwanese subjects with a family history of CVD than in those without it (31.2 vs. 18.8%, odds ratio = 1.97, 95% confidence interval = 1.084-3.579, p = 0.035). Siblings with the B1B1 genotype had lower levels of serum high-density lipoprotein cholesterol (HDL-C) than siblings with either B1B2 (46.7 +/- 11.0 vs. 52.5 +/- 11.1 mg/dl, p = 0.034) or B2B2 genotypes (46.7 +/- 11.0 vs. 55.2 +/- 9.6 mg/dl, p = 0.01).

CONCLUSION

CETP TaqIB polymorphism is associated with plasma HDL-C levels. The CETP B1B1 genotype may influence the susceptibility to CVD in Taiwan.

Effect of postprandial lipaemia and Taq 1B polymorphism of the cholesteryl ester transfer protein (CETP) gene on CETP mass, activity, associated lipoproteins and plasma lipids

A large number of studies in recent years have investigated the effects of hyperlipidaemias and diabetes on cholesteryl ester transfer protein (CETP) on neutral lipid transfer activity and plasma lipids. There has been an ongoing debate as to whether CETP is pro- or anti-atherogenic as it provides a mechanism for the transfer of cholesterol from the cardioprotective HDL subfraction to the potentially atherogenic LDL subfraction. This study was designed to investigate whether there was significant variability of CETP mass and activity in a large normolipidaemic population and whether there is an association between CETP and plasma lipoprotein composition. The presence of a known polymorphism of CETP gene (Taq 1B) was investigated to see if there was any association between this polymorphism and CETP mass and activity, and plasma lipids. There was significant (P < 0·0001) increase in CETP mass and activity in plasma postprandially at 6 h. Using multiple stepwise regression analysis there was significant association with fasting CETP mass and activity (β = 0·055; P = 0·002) and triacylglycerol-rich lipoprotein (β = 0·013; P = 0·005) and postprandial CETP mass (β = 0·254; P = 0·007). Repeated-measures analysis showed a strong association between the absence of Taq 1B polymorphism and low CETP mass and elevated HDL- and HDL2-cholesterol and HDL-phospholipid concentrations than did those who were homozygous or heterozygous for the presence of the restriction site.

Cholesteryl ester-transfer protein (CETP) polymorphism and the association of acute coronary syndromes by obesity status in Greek subjects: the CARDIO2000-GENE study

OBJECTIVE

Cholesterol ester transfer protein (CETP) regulates plasma lipid distribution. The present study aimed to investigate whether the CETP gene (Taq1B) polymorphism predisposes to Acute Coronary Syndromes (ACS) depending on obesity status.

METHODS

We studied demographic, lifestyle and clinical information in 237 hospitalized patients (185 males) with a first event of an ACS and 237 controls matched by age and sex. CETP Taq1B genotyping was performed by PCR-RFLP analysis.

RESULTS

Overall, the CETP genotype frequencies were, in patients: 14% (n = 33), 35% (n = 83) and 51% (n = 121) and in controls: 17% (n = 39), 33% (n = 78) and 50% (n = 120) for B2B2, B1B1 and B1B2 respectively (p = 0.72). A significant interaction (p for interaction <0.001) was observed between obesity status and CETP concerning the likelihood of having ACS. Therefore, we stratified our analysis by obesity status and observed that B2B2 was associated with a 0.27 times lower likelihood of having ACS among normal-weight people (OR = 0.27, p = 0.02). No significant relationships were observed among overweight or obese participants.

CONCLUSIONS

These findings provide evidence of a protective effect of the B2B2 genotype of the CETP Taq1B polymorphism on the likelihood of having a first event of ACS in normal-weight persons.

Plasma cholesteryl ester transfer protein concentrations predict cardiovascular events in patients with coronary artery disease treated with pravastatin

OBJECTIVE

The B1B1 variant of the cholesteryl ester transfer protein (CETP) TaqIB polymorphism and high plasma CETP concentrations are associated with favourable angiographic outcomes in pravastatin-treated patients suffering from coronary artery disease (CAD). The purpose of the present study was to test whether CETP TaqIB genotypes and/or plasma CETP concentrations at baseline also predict clinical end-points in patients with CAD.

DESIGN

Prospective longitudinal observational study.

SETTING

Primary care doctors (n=88) and hospitals (n=7) in Austria.

SUBJECTS

A total of 1620 men and women with preexisting CAD were recruited and plasma lipids were determined at study entry. 1389 hypercholesterolaemic patients were included and 1002 patients completed the follow-up.

INTERVENTIONS

In all patients treatment with pravastatin was started and patients were followed up for 2 years.

MAIN OUTCOME MEASURES

Cardiovascular events.

RESULTS

One hundred patients suffered at least one cardiovascular event. We observed significantly more events in patients within the lowest compared with the highest quartile of plasma CETP concentrations (odds ratio 3.20, CI95 1.65-6.23; P=0.001, adjusted for known risk factors of CAD). No significantly different numbers of cardiovascular events were found between CETP TaqIB genotypes.

CONCLUSIONS

Plasma CETP concentrations, but not CETP TaqIB genotypes, predict cardiovascular events in patients with CAD treated with pravastatin. Despite higher LDL cholesterol concentrations, high plasma CETP concentrations at baseline are associated with fewer cardiovascular events compared with low plasma CETP concentrations in CAD patients treated with pravastatin.

Effects of Cholesteryl Ester Transfer Protein TAQ1B Polymorphism in Renal Transplant Patients

BACKGROUND

Dyslipidemia is an important complication in renal transplant patients. Cholesteryl ester transfer protein (CETP) mediates the exchange of cholesteryl ester between high density lipoproteins and low density lipoproteins. The aim of this study was to investigate CETP Taq1B gene polymorphism and lipid abnormalities in renal transplant patients.

METHODS

We studied 29 renal transplant patients and 29 healthy controls. CETP Taq1B polymorphism was determined by polymerase chain reaction and restriction fragment length polymorphism techniques. Serum lipid levels were measured enzymatically. Statistical analyses was performed by SPSS for Windows version 7.5.

RESULTS

The frequencies of CETP Taq1B B1B1, B1B2, and B2B2 genotypes in patients were 44.8%, 34.5%, and 20.7%; and in control subjects, 37.9%, 37.9%, and 24.2%, respectively. The patients with B1B1 genotype displayed higher levels of total cholesterol (TC), triglycerides, low density lipoprotein-cholesterol (LDL-C), very low density lipoprotein-cholesterol (VLDL-C), and diastolic blood pressure (DBP). (P<.05). Also, patients showing a B1 allele had higher levels of TC, LDL-C, VLDL-C, and DBP compared to healthy controls (P<.05).

CONCLUSION

We observed that CETP Taq1B B1 allele and B1B1 genotype have effects on the serum lipid profile among renal transplant patients.

The association between high-density lipoprotein cholesterol level and cholesteryl ester transfer protein TaqIB gene polymorphism is influenced by alcohol drinking in a population-based sample

Cholesteryl ester transfer protein (CETP) is a key enzyme in high-density lipoprotein (HDL) cholesterol metabolism. We studied the association between CETP TaqIB polymorphism and the HDL cholesterol levels considering environmental factors in a population-based sample consisting of 1729 participants who did not use lipid-lowering agents (659 men and 1070 women). The CETP TaqIB genotypes were determined by PCR-RFLP analysis. The serum HDL cholesterol levels of female participants with the B2B2 genotype were significantly higher than those with other genotypes (p<0.001). Multiple regression analysis with covariates such as age, waist to hip (W/H) ratio, alcohol drinking, current smoking, non-HDL cholesterol, and logarithm of triglyceride revealed that the CETP TaqIB genotype was an independent determinant of HDL cholesterol levels in men (p=0.049) and women (p<0.001). Subgroup analysis revealed that an interaction was observed between the CETP TaqIB polymorphism and alcohol consumption in the regulation of HDL cholesterol levels in men (p=0.049) and women (p=0.022). No interactions were observed between the CETP TaqIB polymorphism and current smoking status, body mass index, or W/H ratio in the regulation of HDL cholesterol levels. The association between the CETP TaqIB polymorphism and HDL cholesterol levels was more evident in alcohol consumers than in non-drinkers.

Effect of the cholesteryl ester transfer protein genotypes on plasma lipid and lipoprotein levels in Vietnamese children

Cholesteryl ester transfer protein (CETP) is understood to play a regulatory role in HDL cholesterol (HDLC) metabolism. In this study, the effect of CETP genotypes on plasma lipid and lipoprotein levels in 348 Vietnamese girls (aged 7-9) with different nutritional conditions was analyzed. The two mutations, intron 14 G(+1)-to-A (I14A) and Asp 442 to Gly within exon 15 (D442G), and the TaqIB polymorphism in the CETP gene were identified by an Invader assay. The D442G mutation was present with a frequency of 0.034, while the I14A mutation was absent. HDLC levels were significantly higher in carriers of the D442G mutation than in noncarriers, regardless of the nutritional status. Low-density lipoprotein (LDL) cholesterol and triglyceride levels were not significantly lower in carriers of D442G mutation. The frequency of the TaqIB2 allele was 0.34, which was lower than that observed in other Asian populations. TaqIB2B2 carriers also had significantly higher HDLC levels, but this association was weaker than that of the D442G mutation. Overall, genetic variations at the CETP gene locus may account for a significant proportion of HDLC variation in Vietnamese children.

Effects of ethanol on lipids and atherosclerosis

Moderate alcohol consumption is associated with an increase in plasma high density lipoprotein (HDL) cholesterol concentration and a decrease in low density lipoprotein (LDL) cholesterol concentration. Changes in the concentration and composition of lipoproteins are estimated to account for more than half of alcohol's protective effect for coronary heart disease. Alcohol intake also affects plasma proteins involved in lipoprotein metabolism: cholesteryl ester transfer protein, phospholipid transfer protein, lecithin:cholesterol acyltransferase, lipoprotein lipase, hepatic lipase, and phospholipases. In addition, alcohol intake may result in acetaldehyde modification of apolipoproteins. Furthermore, "abnormal" lipids, phosphatidylethanol and fatty acid ethyl esters are formed in the presence of ethanol and are associated with lipoproteins in plasma. Ethanol and ethanol-induced modifications of lipids may modulate the effects of lipoproteins on the cells in the arterial wall. The molecular mechanisms involved in these processes are complex, requiring further study to better understand the specific effects of ethanol in the pathogenesis of atherosclerosis. This review discusses the effects of ethanol on lipoproteins and lipoprotein metabolism, as well as the novel effects of lipoproteins on vascular wall cells.

ATP-binding cassette transporter A1: a cell cholesterol exporter that protects against cardiovascular disease

Blood high-density lipoprotein (HDL) levels are inversely related to risk for cardiovascular disease, implying that factors associated with HDL metabolism are atheroprotective. One of these factors is ATP-binding cassette transporter A1 (ABCA1), a cell membrane protein that mediates the transport of cholesterol, phospholipids, and other metabolites from cells to lipid-depleted HDL apolipoproteins. ABCA1 transcription is highly induced by sterols, a major substrate for cellular export, and its expression and activity are regulated posttranscriptionally by diverse processes. Liver ABCA1 initiates formation of HDL particles, and macrophage ABCA1 protects arteries from developing atherosclerotic lesions. ABCA1 mutations can cause a severe HDL deficiency syndrome characterized by cholesterol deposition in tissue macrophages and prevalent atherosclerosis. Genetic manipulations of ABCA1 expression in mice also affect plasma HDL levels and atherogenesis. Metabolites elevated in individuals with the metabolic syndrome and diabetes destabilize ABCA1 protein and decrease cholesterol export from macrophages. Moreover, oxidative modifications of HDL found in patients with cardiovascular disease reduce the ability of apolipoproteins to remove cellular cholesterol by the ABCA1 pathway. These observations raise the possibility that an impaired ABCA1 pathway contributes to the enhanced atherogenesis associated with common inflammatory and metabolic disorders. The ABCA1 pathway has therefore become an important new therapeutic target for treating cardiovascular disease.

An interaction between the TaqIB polymorphism of cholesterol ester transfer protein and smoking is associated with changes in plasma high-density lipoprotein cholesterol levels in Turks

Low levels of high-density lipoprotein cholesterol (HDL-C) are an independent risk factor for atherosclerosis. We investigated the effects of the TaqIB polymorphism of cholesterol ester transfer protein (CETP) on CETP activity and plasma HDL-C levels in random nondiabetic and self-reported diabetic subjects in a population with very low HDL-C levels. The rare B2B2 genotype was associated with significantly higher HDL-C levels and lower CETP activity in random subjects and with higher HDL-C in diabetic subjects. After stratification of random subjects by smoking status, the common B1B1 genotype was associated with lower HDL-C levels than the B2B2 genotype. Although smoking was associated with lower HDL-C, especially in men, HDL-C levels between smokers and nonsmokers were not different in subjects with the B1B2 or B2B2 genotypes. However, smoking (20+ cigarettes/day) was associated with a marked reduction in HDL-C in the B1B1 subjects. The B1B1/smoking interaction was not reflected in a difference in CETP activity. High triglycerides and elevated body mass index (BMI) lower HDL-C. The B2B2 genotype was associated with the highest HDL-C levels, and these levels were significantly lower in the hypertriglyceridemic subjects (>or=50th percentile). The lowest HDL-C levels were seen in hypertriglyceridemic subjects with the B1B1 genotype. Although BMI (>or=50th vs<50th percentile) did not affect HDL-C in B2B2 subjects, a high BMI was associated with markedly lower HDL-C in B1B1 subjects. Thus, HDL-C levels in Turks may be modulated by an interaction between the CETP TaqIB polymorphism and smoking, as well as an interaction with hypertriglyceridemia and BMI.

Functional interaction between −629C/A, −971G/A and −1337C/T polymorphisms in the CETP gene is a major determinant of promoter activity and plasma CETP concentration in the REGRESS Study

Cholesteryl ester transfer protein (CETP) plays a key role in the determination of high-density lipoprotein (HDL) levels via its action on intravascular HDL metabolism. The TaqIB polymorphism of the CETP gene is associated with plasma CETP and high-density lipoprotein cholesterol (HDL-C) levels and with premature coronary artery disease. Such associations appear to result from linkage disequilibrium between TaqIB and other functional polymorphisms. To date, only one functional promoter variant, which may explain the effects of TaqIB, has been identified at position -629 in the CETP gene. Here we describe a C/T polymorphism located at position -1337 in the human CETP gene (C allele frequency: 0.684), which is significantly associated with plasma HDL-C and CETP levels (P=0.0001 and P<0.0001, respectively). Transient transfection of a reporter gene construct containing the CETP promoter from -1707/+28 in liver cells (HepG2) revealed that the -1337T allele was expressed to a significantly lower degree (-34%, P<0.0001) than the -1337C allele. In addition, we clearly demonstrated that the -971G/A polymorphism is functional and that its functionality is intimately linked to the presence of the -1337 site. In vitro evaluation of potential interaction between -1337C/T and other functional variants of the CETP gene (-971G/A and -629C/A) demonstrated that these three functional CETP promoter polymorphisms can interact together to determine the overall activity of the CETP gene and thus contribute significantly to variation in plasma CETP mass concentration.

Gene polymorphisms affecting HDL-cholesterol levels in the normolipidemic population

BACKGROUND AND AIM

HDL-cholesterol (HDL-C) is inversely related to the risk of ischemic heart disease. Many genes are reported to affect HDL-C serum levels in both hyperlipidemic and normolipidemic populations, though the data are controversial. We examined the effect of common gene polymorphisms known to interfere with HDL-C metabolism (apolipoprotein E, cholesterol ester transfer protein and apolipoprotein A-IV gene polymorphisms) on HDL-C plasma levels in normolipidemic subjects.

METHODS AND RESULTS

The study population consisted of 200 normolipidemic individuals visiting our clinic for a routine check-up. None of the above gene polymorphisms affected HDL-C levels in our population. However, participants carrying the allele E4 of the apolipoprotein (apo) E gene, the allele B1 of the TaqIB polymorphisms in the cholesterol ester transfer protein (CETP) gene and the allele T of the apoA-IV gene (A to T polymorphism at site 347) (n = 28) had statistically significantly lower HDL-C levels compared to those not carrying the above allele combination (0.99+/-0.33 vs 1.28+/-0.35 mmol/L, p = 0.04).

CONCLUSION

In this study, we describe a subgroup of normolipidemic individuals with low HDL-C levels due to genetic variability, and we discuss the underlying possible mechanisms involved.

TaqIB polymorphism in CETP gene: the influence on incidence of cardiovascular disease in statin-treated patients with familial hypercholesterolemia

The effects of TaqI restriction fragment length polymorphism of the CETP gene on the occurrence of cardiovascular disease (CVD) events were investigated in patients with familial hypercholesterolemia (FH). A total of 300 FH patients, of which 116 (39%) had CVD at the start of the study, were treated with statins during a mean period of 8.5 years. The distribution of Taq1B genotypes was 31% B1B1, 49% B1B2, and 20% B2B2. No differences were found at baseline between the three genotypes, except for an association of the B1 allele with lower high-density lipoprotein (HDL)-cholesterol levels (P=0.003). All patients were put on statins within 6-8 weeks after the first visit; about 60% received simvastatin (20-40 mg daily) and 40% either pravastatin (40 mg daily) or atorvastatin (20-40 mg daily). The different statin treatments were similar for all groups. The mean change of plasma HDL-cholesterol, low-density lipoprotein-cholesterol, and triglyceride concentration during statin therapy was similar for the three genotypes. During follow-up, new CVD events were recorded in 22 (37%) of the B2B2 patients (n=59) and in 67 (28%) of B1 allele carriers (n=241) (P=0.36). The relative risk for CVD events, after adjustment for age, gender, and CVD at intake, was 1.8 (CI: 1.1-3.0) for B2B2 carriers compared to B1 allele carriers. The Taq1B polymorphism is a significant predictor of future CVD events in statin-treated patients with FH. In spite of similar improvement of the lipoprotein profile during statin therapy, our FH patients with the B2B2 genotype may have a higher CVD risk in comparison with the B1 allele carriers.

Cholesteryl ester transfer protein TaqIB polymorphism and its relation to parameters of the insulin resistance syndrome in an Austrian cohort

The cholesteryl ester transfer protein (CETP) is responsible for the exchange of triglycerides and cholesteryl esters between lipoprotein particles leading to an increased hepatic clearance of HDL-cholesteryl esters. A high CETP activity reduces serum HDL levels, whereas persons without CETP activity have high HDL levels. We investigated the association of the TaqIB CETP polymorphism and various parameters of the insulin resistance syndrome in a cross sectional population based study. We included 1029 persons without known cardiovascular disease or diabetes mellitus consecutively enrolled in our SAPHIR program (Salzburg Atherosclerosis Prevention program in persons with a High Infarction Risk). Numerous clinical and laboratory data were accomplished. Insulin sensitivity was measured by a short insulin tolerance test. The TaqIB CETP polymorphism was determined by PCR, TaqI restriction and electrophoresis. 35.2% were homozygous for the prevalence (B1B1), 46.7% were heterozygous (B1B2), and 18.1% homozygous for the absence (B2B2) of the restriction site. HDL cholesterol and apolipoprotein A1 were lower and small dense low-density lipoproteins (sdLDL) higher in B1B1 compared to B2B1 and B2B2 persons. In women, we found a significant interaction effect between CETP genotype and adiposity for HDL cholesterol. B1B1 women with a BMI and a waist circumference above the median had 9.7 mg/dl lower HDL than B1B2 and 9.1 mg/dl lower HDL than B2B2 women (P < 0.001). In men, no interaction effect but a marked genotype to HDL correlation was found. There was a high CETP effect on sdLDL detected in men (P = 0.001). B1B1 men had sdLDL in 36%, B1B2 in 24.6%, and B2B2 in only 14.5%. Men with adiposity and insulin resistance had twice as many sdLDL as insulin sensitive men. We found a significant sex specific effect of the TaqIB CETP polymorphism on the insulin resistance parameters HDL-cholesterol and sdLDL in an Austrian population based study.

CETP polymorphisms associated with HDL cholesterol may differ from those associated with cardiovascular disease

To better understand the role of cholesteryl ester transfer protein (CETP) in cardiovascular disease, nine polymorphisms spanning the gene from the upstream promoter region to beyond the 3'UTR were genotyped in 2553 individuals from multiple ethnic groups and with different cardiovascular disease profiles. The frequency of four of these SNPs varied by 40-300% between Caucasians and African Americans. SNPs in each ethnic group fell into two haploblocks with significant linkage disequilibrium within each block. SNPs in the 5' haploblock were significantly associated with HDL cholesterol while SNPs in the 3' haploblock were, at best, only weakly associated with HDL-C. One SNP in the 3' haploblock (rs1800774 in intron 12) was highly associated with history of myocardial infarction even though it was not associated with HDL-C. This association was driven by the effect in Caucasian women where 11.9% of the women with no history of MI are homozygous for the less common allele while 23.7% of those with a history of MI share this genotype. In addition, this SNP was highly associated with BMI among Caucasians (p < 0.0001). The association of HDL-C with CETP genotype was found to be independent of smoking or alcohol consumption. These results replicate some earlier findings and also help to explain some of the apparent contradictions in the literature surrounding the role of CETP in modulating HDL-C and cardiovascular disease.

Polymorphisms in Four Genes Related to Triglyceride and HDL-cholesterol Levels in the General Japanese Population in 2000

We studied the association of six common polymorphisms of four genes related to lipid metabolism with serum lipid levels. We selected single-nucleotide polymorphisms (SNPs) in the genes for cholesteryl ester transfer protein (CETP), lipoprotein lipase (LPL), hepatic lipase (LIPC), and apolipoprotein CIII (APOC3), and studied 2267 individuals randomly selected from the participants of Serum Lipid Survey 2000. There was a significant association of CETP polymorphism (D442G, Int14 +1 G --> A, and TaqIB), LPL polymorphism (S447X), and LIPC polymorphism (-514 --> CT) with HDL-cholesterol levels. We also found a significant association of LPL polymorphism (S447X) and APOC3 polymorphism (SstI) with triglyceride levels. This is the largest database showing the association of common genetic variants in lipid metabolism with serum lipid levels in the general Japanese population. Further study is necessary to elucidate the role of these gene polymorphisms in cardiovascular events.

Molecular mechanisms of cholesteryl ester transfer protein deficiency in Japanese

Plasma cholesteryl ester transfer protein (CETP) facilitates the transfer of cholesteryl ester (CE) from high density lipoprotein (HDL) to apolipoprotein B-containing lipoproteins. Since CETP regulates the plasma levels of HDL cholesterol and the size of HDL particles, CETP is considered to be a key protein in reverse cholesterol transport (RCT), a protective system against atherosclerosis. The importance of plasma CETP in lipoprotein metabolism was demonstrated by the discovery of CETP-deficient subjects with marked hyperalphalipoproteinemia (HALP). Genetic CETP deficiency is the most important and common cause of HALP in the Japanese. Ten mutations of the CETP gene have been demonstrated as causes of HALP, including two common mutations: an intron 14 splicing defect (Int14 + 1 G --> A) and an exon 15 missense mutation (D442G). The subjects with CETP deficiency show a variety of abnormalities in the concentration, composition, and function of both HDL and low density lipoprotein (LDL). CETP deficiency is considered a physiological state of impaired RCT, which may possibly lead to the development of atherosclerosis despite high HDL cholesterol levels. However, the pathophysiological significance of CETP in terms of atherosclerosis has been controversial. Epidemiological studies in Japanese-Americans living in Hawaii and Japanese in the Omagari area, where HALP subjects with an intron 14 splicing defect of the CETP gene are markedly frequent, have shown a relatively increased incidence of coronary atherosclerosis in CETP deficiency. On the other hand, the TaqIB polymorphism-B2 allele with low CETP mass and increased HDL cholesterol has been related to a decreased risk for coronary heart disease (CHD) in many studies, including the Framingham Offspring Study. The current review focused on the characterization of the Japanese subjects with CETP deficiency, including our recent findings.

Role of genetic factors (CETP gene Taq I B polymorphism and Apo A-I gene Msp I polymorphism) in serum HDL-C levels in women

BACKGROUND AND AIM

Plasma high density lipoprotein cholesterol (HDL-C) levels are determined by a variety of environmental and genetic factors. The cholesteryl ester transfer protein (CETP) and apolipoprotein A-I (Apo A-I) are considered to be associated with HDL-C metabolism. The aim of this study was to investigate the relationship between the CETP gene Taq I B and Apo A-I gene Msp I polymorphisms and plasma lipid levels taking into account environmental factors, and to determine the combined effects of these polymorphisms on HDL-C levels in Japanese women.

METHODS AND RESULTS

The study involved 270 Japanese women aged 30-69 years. We found a significant association between the CETP genotypes and HDL-C levels (p=0.0020), which were also associated with the Apo A-I gene (M1) polymorphism. Stepwise multiple regression analysis revealed that both the CETP Taq I B and Apo A-I gene (M1) genotypes were independent predictive variables. The strength of the association between the Apo A-I (M1) subgroup and HDL-C levels was reduced in the subjects with a high Body Mass Index (BMI). The combination of genotypes provided more detailed information about HDL-C levels. The "high risk" combination of the M1+ (M1+/+) and B1B1 genotypes was associated with the lowest HDL-C level (1.52+/-0.36 mmol/L), and the "low risk" combination of the M1- (M1+/- or M1-/-) and B2B2 genotypes was associated with the highest HDL-C levels (2.06+/-0.34 mmol/L).

CONCLUSIONS

Our results suggest that the combination of the two polymorphisms influences HDL-C levels in women, and that the association between genetic factors and HDL-C levels is altered by environmental factors. They may also help to detect individuals with low HDL-C levels at high risk for coronary artery syndrome.

Effects of cholesterol ester transfer protein Taq1B gene polymorphism on serum lipoprotein levels in Turkish coronary artery disease patients

To evaluate the effect of cholesterol ester transfer protein (CETP) Taq1B gene polymorphism on serum lipid profile in Turkish coronary artery disease (CAD) patients, we investigated Taq1B gene polymorphism of CETP and serum lipid levels in 111 controls and in 173 CAD patients with myocardial infarction. There were no significant differences in the allele distribution at this polymorphic locus between the population sample and patients with coronary artery disease with myocardial infarction. To detect the association between the Taq1B RFLP and serum lipid levels, we determined the serum concentrations of total cholesterol, triglycerides and high density lipoprotein cholesterol (HDL-C) in the subjects studied and correlated the results to the Taq1B RFLP. Patients with Taq B1B1 genotypes had lower HDL-C levels than patients with B2B2 genotype (p = 0.003). Also in control subjects with Taq B1B1 genotype, lower HDL-C levels (p = 0.05) and higher triglyceride levels (p = 0.017) and body mass index (p = 0.05) were observed compared with control subjects with the B1B2 genotype. It was observed that in our population the distribution of CETP Taq1B genotypes is similar to other populations (except Greeks). The present study demonstrates that CETP Taq1B gene polymorphism may be responsible for low HDL cholesterol levels in patients with CAD and in healthy controls in Turkey.

Alterations in high-density lipoprotein metabolism and reverse cholesterol transport in insulin resistance and type 2 diabetes mellitus: role of lipolytic enzymes, lecithin:cholesterol acyltransferase and lipid transfer proteins

Insulin resistance and type 2 diabetes mellitus are generally accompanied by low HDL cholesterol and high plasma triglycerides, which are major cardiovascular risk factors. This review describes abnormalities in HDL metabolism and reverse cholesterol transport, i.e. the transport of cholesterol from peripheral cells back to the liver for metabolism and biliary excretion, in insulin resistance and type 2 diabetes mellitus. Several enzymes including lipoprotein lipase (LPL), hepatic lipase (HL) and lecithin: cholesterol acyltransferase (LCAT), as well as cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP), participate in HDL metabolism and remodelling. Lipoprotein lipase hydrolyses lipoprotein triglycerides, thus providing lipids for HDL formation. Hepatic lipase reduces HDL particle size by hydrolysing its triglycerides and phospholipids. A decreased postheparin plasma LPL/HL ratio is a determinant of low HDL2 cholesterol in insulin resistance. The esterification of free cholesterol by LCAT increases HDL particle size. Plasma cholesterol esterification is unaltered or increased in type 2 diabetes mellitus, probably depending on the extent of triglyceride elevation. Subsequent CETP action results in transfer of cholesteryl esters from HDL towards triglyceride-rich lipoproteins, and is involved in decreasing HDL size. An increased plasma cholesteryl ester transfer is frequently observed in insulin-resistant conditions, and is considered to be a determinant of low HDL cholesterol. Phospholipid transfer protein generates small pre beta-HDL particles that are initial acceptors of cell-derived cholesterol. Its activity in plasma is elevated in insulin resistance and type 2 diabetes mellitus in association with high plasma triglycerides and obesity. In insulin resistance, the ability of plasma to promote cellular cholesterol efflux may be maintained consequent to increases in PLTP activity and pre beta-HDL. However, cellular cholesterol efflux to diabetic plasma is probably impaired. Besides, cellular abnormalities that are in part related to impaired actions of ATP binding cassette transporter 1 and scavenger receptor class B type I are likely to result in diminished cellular cholesterol efflux in the diabetic state. Whether hepatic metabolism of HDL-derived cholesterol and subsequent hepatobiliary transport is altered in insulin resistance and type 2 diabetes mellitus is unknown. Specific CETP inhibitors have been developed that exert major HDL cholesterol-raising effects in humans and retard atherosclerosis in animals. As an increased CETP-mediated cholesteryl ester transfer represents a plausible metabolic intermediate between high triglycerides and low HDL cholesterol, studies are warranted to evaluate the effects of these agents in insulin resistance- and diabetes-associated dyslipidaemia.

The cholesteryl ester transfer protein Taq1B gene polymorphism predicts clinical benefit of statin therapy in patients with significant coronary artery disease

BACKGROUND

Cholesteryl ester transfer protein (CETP) regulates plasma lipid distribution. A polymorphism in the CETP gene (Taq1B) is associated with CETP activity, HDL concentration, atherosclerosis progression, and response to statins, and may influence cardiovascular (CV) events. We studied CETP Taq1B genotype, plasma HDL, and clinical events among all patients and patients stratified by statin treatment.

METHODS

Consenting patients (n = 2531) with significant coronary artery disease (> or =1 lesion of > or =70% stenosis) undergoing coronary arteriography were genotyped, grouped by statin prescription at hospital discharge, and prospectively followed-up for the outcomes of all-cause mortality and myocardial infarction.

RESULTS

CETP Taq1B genotype frequencies were: B1B1, 32.9%; B1B2, 50.3%; and B2B2 16.8%. Plasma HDL was reduced for B1B1 patients (33 +/- 12 mg/dL, vs 36 +/- 13 mg/dL and 36 +/- 13 mg/dL for B1B2 and B2B2, respectively, P for trend =.003). Overall, event rates did not differ between genotypes. Event rates were similar among untreated (24.8%) and statin-treated (24.2%) B1 homozygotes (P = NS); statins significantly reduced events for B1B2 subjects (28.0% vs 21.0%, P =.009) and for B2B2 subjects (26.4% vs 17.4%, P =.048). Therapeutic benefit for B2 carriers remained after adjustment for covariates, and regression interaction analysis showed that B2 carriers experienced reduced events (relative risk [RR] 0.62, 95% CI 0.45-0.86), but statins did not benefit those with B1B1 (RR 1.09, 95% CI 0.70-1.7; P for interaction =.02). Findings were similar for the end point of death alone, although a modest benefit was seen in B1B1 patients (RR 0.67, P =.10), in addition to the strong benefit for B1B2 (RR 0.53, P =.001) and B2B2 (RR 0.28, P =.001).

CONCLUSIONS

The CETP Taq1B polymorphism is associated with differential HDL levels but no significant differential in CV risk in the absence of treatment. Importantly, however, CV event reduction by statin therapy is substantially enhanced in the presence of a B2 allele. Our findings suggest, for the first time, the potential of CETP Taq1B genotyping to enable more effective, pharmacogenetically directed therapy.

Cholesterol ester transfer protein, apolipoprotein E and lipoprotein lipase genotypes in patients with coronary artery disease in the Turkish population

The aim of this study was to compare patients with coronary artery disease (CAD) to healthy objects, in order to explore a possible association between CAD and the variants in the gene encoding cholesterol ester transfer protein (CETP), apolipoprotein E (Apo E) and lipoprotein lipase (LPL). The relationship between CETP MspI, apo E and LPL PvuII gene polymorphisms and serum lipids were investigated in 173 patients with CAD and 111 healthy controls. The frequency of Apo epsilon4 (p < 0.05) and CETP M1 (p < 0.01) alleles were higher in the CAD group than in the control group. In the CAD group, those with the Msp M1 allele had higher levels of total cholesterol (TC) (p = 0026) and low-density lipoprotein cholesterol (LDL-C) than those with the Msp M2 allele. Subjects with an epsilon2 allele had the lowest levels of TC and LDL-C, while subjects with the epsilon4 allele had the highest. In the control group, CETP, the Msp M2 allele was associated with a higher level of high-density lipoprotein cholesterol (HDL-C) (p = 0.012) than the Msp M1 allele. The distributions of LPL genotype and allele did not differ between the CAD and control groups. The present study demonstrates that the CETP Msp1 and Apo E gene polymorphisms are associated with variations in lipids in patients with CAD and healthy controls in Turkish population.

No physical activity x CETP 1b.-629 interaction effects on lipid profile

INTRODUCTION/PURPOSE

Being physically active may improve the lipid profile by increasing high-density lipoprotein (HDL) cholesterol (HDL-C) concentrations. Cholesteryl ester transfer protein (CETP) transfers cholesteryl esters from HDL to lipoproteins of lower density. The potential interactive effects of physical activity and the CETP A-C polymorphism on exon 1b.-629 (CETP 1b.-629) with lipid profile were investigated in a population-based cross-sectional survey.

METHODS

1720 men and women, ages 35-74 yr, were randomly selected from the general adult population of Geneva, Switzerland, throughout 1999-2000. A validated physical activity questionnaire measured total energy expenditure and the percentage thereof used in high-intensity activities (% high-intensity activity, e.g., brisk walking, sports). CETP 1b.-629 was assayed with PCR and allele-specific oligonucleotide hybridization. The study had 80% power to detect lipid profile differences from 0.10 to 0.15 mmol x L-1 ( approximately 4-6 mg x dL-1) between gender-specific (CETP genotype x % high-intensity activity) subgroups.

RESULTS

HDL-C (mmol x L-1) was higher in men and women with the AA genotype (respectively, 1.26 and 1.56) versus those with CC (1.14 and 1.46) (P < 0.0001, P < 0.002). Before stratification into CETP subgroups, a greater % high-intensity activity (upper tertile) was associated with higher HDL-C only in men (1.24 vs 1.19 in lower tertile, P < 0.0005). However, no statistically significant (CETP 1b.-629 x % high-intensity activity) interactions with lipid profile were detected in either gender.

CONCLUSION

The effects of the CETP 1b.-629 A-C polymorphism on blood lipid concentrations appear to be unchanged by the different observed physical activity levels in a mostly sedentary population.

Natural genetic variation as a tool in understanding the role of CETP in lipid levels and disease

Since the identification of cholesteryl ester transfer protein (CETP), its role in the modulation of HDL levels and cardiovascular disease has been debated. With the early detection of genetic variants followed by the finding of families deficient in CETP, genetic studies have played a large role in the attempts to understand the association of CETP with lipids and disease; however, results of these studies have often led to disparate conclusions. With the availability of a greater variety of genetic polymorphisms and larger studies in which disease has been examined, it is now possible to compare the breadth of CETP genetic studies and draw better conclusions. The most broadly studied polymorphism is TaqIB for which over 10,000 individuals have been genotyped and had HDL levels determined. When these studies are subjected to a meta-analysis, the B2B2 homozygotes are found to have higher HDL levels than B1B1 homozygotes (0.12 mmol/l, 95% CI = 0.11-0.13, P < 0.0001). A similar analysis of the I405V polymorphism yields 0.05 mmol/l higher HDL levels in 405VV homozygotes than in 405II homozygotes (95% CI = 0.03-0.07, P < 0.0001). The implications of these studies for cardiovascular disease will be addressed.

The TaqIB and -629C>A polymorphisms at the cholesteryl ester transfer protein locus: associations with lipid levels in a multiethnic population. The 1998 Singapore National Health Survey

The Singapore population comprises Chinese, Malays and Asian Indians. Within this population, Asian Indians have the highest rates of coronary heart disease, whereas Chinese have the lowest. Conversely, Indians have the lowest high-density lipoprotein cholesterol (HDL-C) concentrations, followed by Malays and Chinese. We studied the TaqIB and -629C>A polymorphisms at the CETP locus in 1300 Chinese, 364 Malay and 282 Asian Indian men, and in 1558 Chinese, 397 Malay and 306 Asian Indian women, to determine whether these polymorphisms are responsible for the ethnic difference in HDL-C concentration. The frequency of the B2 allele in Chinese, Malays and Indians was 0.384, 0.339 and 0.449 in men, and 0.379, 0.329 and 0.415 in women, respectively (p < 0.001). For the A-629 allele, the relative frequencies were 0.477, 0.423 and 0.592 in men and 0.486, 0.416 and 0.575 in women (p < 0.001). The two polymorphisms were in linkage disequilibrium (D / Dmax= 0.9772, p < 0.00001). The B2 and the A-629 alleles were associated with increased HDL-C concentrations in a dose-dependent manner. The B2 allele continued to show an association with HDL-C concentration, even after controlling for the genotype at position -629. Dietary cholesterol showed a significant interaction with the TaqIB polymorphism in determining HDL-C concentrations in Indians and Malays, but not in Chinese. In conclusion, the high frequencies of these polymorphisms in Asian Indians could not explain the observed ethnic differences in HDL-C concentration. Moreover, we observed an ethnic-specific interaction among dietary cholesterol, the TaqIB polymorphism and HDL-C concentrations.