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

Characteristics of Coronary Artery Disease Patients Who Have a Polymorphism in the Cholesterol Ester Transfer Protein (CETP) Gene

BACKGROUND/AIM

Cholesterol ester transfer protein (CETP) is responsible for the transformation of high density lipoprotein (HDL) to low density lipoprotein (LDL) and is a risk factor for atherosclerosis. Our study investigated the association of the rs5883 CETP gene polymorphism with HDL and LDL levels, in 45 coronary artery disease patients and 45 control patients.

MATERIALS AND METHODS

CETP gene polymorphism was detected using Real Time-Polymerase Chain Reaction (RT-PCR). Lipoprotein levels were measured using Quantimetrix system.

RESULTS

There were lack of associaition regarding CETP polymorphism in atherosclerosis and HDL and LDL levels (p>0.05) BMI was higher among coronary artery disease patients (CADP) compared to the control group (28.97±6.38, 26.52±4.39 respectively, p<0.03). Frequency of CADP (82.6 %, n=19) who were taking treatment was higher (17.4 %, n=4) (p<0.00). The frequencies of hypertension and type-2 diabetes were higher among CADP (p<0.00). Families of CADP have more CADP (p<0.02). Small HDL particle levels were higher in the control group (p<0.00).

CONCLUSION

In Turkey, BMI, and frequencies of hypertension and type-2 diabetes were higher among CADP than among healthy controls. Furthermore, the genotypes of the rs5883 CETP gene polymorphism did not differ between CADP and healthy controls.

Additive Antiatherogenic Effects of CETP rs708272 on Serum LDL Subfraction Levels in Patients with CHD Under Statin Therapy

Recently, subfraction analysis of serum low density lipoprotein (LDL) is considered to be a better predictor of the risk of coronary heart disease (CHD) compared to the other lipid parameters. The aim of this study was to examine the effects of the HDL-associated Taq1B (rs708272) SNP of cholesterol ester transfer protein (CETP) gene on serum LDL subfractions in patients with CHD. Serum lipid levels were measured enzymatically and LDL subfraction analysis was carried out by the Lipoprint System (Quantimetrix, CA, USA). The CETP rs708272 SNP was studied in 66 healthy controls and 79 patients with CHD receiving statin therapy by the PCR-RFLP technique. The CHD patients had elevated antiatherogenic LDL-1 subfraction (p = 0.042), decreased atherogenic IDL-C subfraction (p = 0.023), and total IDL (p = 0.030) levels compared to the healthy controls. The CETP rs708272 Taq1B minor B2 allele was associated with increased levels of antiatherogenic LDL-1 (B2: 0.40 ± 0.20 vs. B1B1: 0.25 ± 0.08, p = 0.004) and large-LDL (LDL 1-2) subfractions in the CHD group (B2 allele: 0.68 ± 0.41 vs. B1B1: 0.42 ± 0.20; p < 0.05), while it was associated with reduced levels of the large-LDL subfraction in healthy subjects (B2 allele: 0.29 ± 0.14 vs. B1B1: 0.54 ± 0.24; p = 0.017). However, there was no statistically significant association between the CETP rs708272 SNP and small dense LDL subfraction (LDL 3-7) and lipoprotein levels (p > 0.05). Our findings have indicated that the CETP rs708272 SNP together with statin therapy may show a favorable effect on antiatherogenic LDL-1 and large-LDL subfractions in CHD patients with an atherogenic effect on large-LDL subfraction in healthy subjects. Based on these results, it can be concluded that the effects of the CETP variation on LDL subfraction could change in cardiometabolic events such as CHD and statin therapy.

Mitochondrial DNA 5178 C/A polymorphism influences the effects of habitual smoking on the risk of dyslipidemia in middle-aged Japanese men

Background

Several genetic polymorphisms have been reported to modify the effects of smoking on serum lipid levels. The objective of this study was to investigate whether longevity-associated mitochondrial DNA 5178 (Mt5178) C/A polymorphism modifies the effects of habitual smoking on the risk of dyslipidemia in middle-aged Japanese subjects.

Methods

A total of 394 male subjects (age, 53.9 ± 7.9 years; mean ± SD) were selected from among individuals visiting the hospital for regular medical check-ups. After Mt5178 C/A genotyping, a cross-sectional study assessing the joint effect of Mt5178 C/A polymorphism and cigarette smoking on the risk of hypo-high-density lipoprotein (HDL) cholesterolemia, hyper-low-density lipoprotein (LDL) cholesterolemia or hypertriglyceridemia was conducted.

Results

For subjects with Mt5178C, the risk of hypo-HDL cholesterolemia increased with the number of cigarettes smoked daily (P for trend = 0.001). On the other hand, the association between Mt5178A genotype and the risk of hypo-HDL cholesterolemia did not appear to depend on the number of cigarettes smoked daily. For those with Mt5178A, the risk of hyper-LDL cholesterolemia or hypertriglyceridemia increased with cigarettes smoked daily (P for trend = 0.017 and P for trend = 0.002, respectively). However, the association between Mt5178C genotype and the risk of hyper-LDL cholesterolemia or hypertriglyceridemia did not depend on the number of cigarettes smoked daily.

Conclusions

The present results suggest that Mt5178 C/A polymorphism modulates the effects of habitual smoking on the risk of dyslipidemia in middle-aged Japanese men.

Turkish population structure and genetic ancestry reveal relatedness among Eurasian populations

Turkey has experienced major population movements. Population structure and genetic relatedness of samples from three regions of Turkey, using over 500,000 SNP genotypes, were compared together with Human Genome Diversity Panel (HGDP) data. To obtain a more representative sampling from Central Asia, Kyrgyz samples (Bishkek, Kyrgyzstan) were genotyped and analysed. Principal component (PC) analysis reveals a significant overlap between Turks and Middle Easterners and a relationship with Europeans and South and Central Asians; however, the Turkish genetic structure is unique. FRAPPE, STRUCTURE, and phylogenetic analyses support the PC analysis depending upon the number of parental ancestry components chosen. For example, supervised STRUCTURE (K=3) illustrates a genetic ancestry for the Turks of 45% Middle Eastern (95% CI, 42-49), 40% European (95% CI, 36-44) and 15% Central Asian (95% CI, 13-16), whereas at K=4 the genetic ancestry of the Turks was 38% European (95% CI, 35-42), 35% Middle Eastern (95% CI, 33-38), 18% South Asian (95% CI, 16-19) and 9% Central Asian (95% CI, 7-11). PC analysis and FRAPPE/STRUCTURE results from three regions in Turkey (Aydin, Istanbul and Kayseri) were superimposed, without clear subpopulation structure, suggesting sample homogeneity. Thus, this study demonstrates admixture of Turkish people reflecting the population migration patterns.

Gene-environment interactions of CETP gene variation in a high cardiovascular risk Mediterranean population

Genome-wide association studies show that cholesteryl ester transfer protein (CETP) single nucleotide polymorphisms (SNPs) are more strongly associated with HDL cholesterol (HDL-C) concentrations than any other loci across the genome. However, gene-environment interactions for clinical applications are still largely unknown. We studied gene-environment interactions between CETP SNPs and dietary fat intake, adherence to the Mediterranean diet, alcohol consumption, smoking, obesity, and diabetes on HDL-C in 4,210 high cardiovascular risk subjects from a Mediterranean population. We focused on the -4,502C>T and the TaqIB SNPs in partial linkage disequilibrium (D'= 0.88; P < 0.001). They were independently associated with higher HDL-C (P < 0.001); this clinically relevant association was greater when their diplotype was considered (14% higher in TT/B2B2 vs. CC/B1B1). No gene-gene interaction was observed. We also analyzed the association of these SNPs with blood pressure, and no clinically relevant associations were detected. No statistically significant interactions of these SNPs with obesity, diabetes, and smoking in determining HDL-C concentrations were found. Likewise, alcohol, dietary fat, and adherence to the Mediterranean diet did not statistically interact with the CETP variants (independently or as diplotype) in determining HDL-C. In conclusion, the strong association of the CETP SNPs and HDL-C was not statistically modified by diet or by the other environmental factors.

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.

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.

Polymorphism in the cholesteryl ester transfer protein gene and the risk of early onset myocardial infarction among cigarette smokers

BACKGROUND

Cigarette smoking and the common B1 allele of the TaqIB polymorphism have both been reported to be associated with increased cholesteryl ester transfer protein (CETP) activity and altered lipoprotein levels. Thus, it is possible that the combined presence of these two respective environmental and genetic factors may enhance cardiovascular risk. We hypothesized that susceptibility to early onset myocardial infarction (MI) among cigarette smokers may be related to the presence of TaqIB polymorphism in the CETP gene.

METHODS

The age at onset of a first MI among current (n = 199), past (n = 345), and never (n = 270) smokers was related to the presence of the TaqIB1 and B2 alleles in a cohort of 814 first MI patients.

RESULTS

Multivariate regression analysis demonstrated that cigarette smoking was associated with a significant increase in the risk for early onset MI only among carriers of the TaqIB1 allele: current smokers with the B1B1 and B1B2 genotypes displayed a respective 9.4 (P < 0.001) and 8.4 (P < 0.001) year reduction in the age at onset of a first MI compared with never smokers, and past smokers with these genotypes exhibited a respective 3.8 (P = 0.003) and 3.7 (P = 0.01) year reduction. By contrast, current and past smoking was not associated with a significant increase in the risk for early onset MI among B2B2 homozygotes (3.0 [P = 0.28] and 0.2 [P = 0.93] year reduction, respectively). The smoking x genotype interaction was statistically significant (P = 0.04).

CONCLUSIONS

The current findings suggest that genetic factors may modify susceptibility to early onset MI among cigarette smokers.

Genetic determinants of plasma lipoproteins

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

Plasma lipid transfer proteins

PURPOSE OF REVIEW

Plasma cholesteryl ester transfer protein and phospholipid transfer protein are involved in lipoprotein metabolism. Conceivably, manipulation of either transfer protein could impact atherosclerosis and other lipid-driven diseases.

RECENT FINDINGS

Cholesteryl ester transfer protein mediates direct HDL cholesteryl ester delivery to the liver cells; adipose tissue-specific overexpression of cholesteryl ester transfer protein in mice reduces the plasma HDL cholesterol concentration and adipocyte size; cholesteryl ester transfer protein TaqIB polymorphism is associated with HDL cholesterol plasma levels and the risk of coronary heart disease. In apolipoprotein B transgenic mice, phospholipid transfer protein deficiency enhances reactive oxygen species-dependent degradation of newly synthesized apolipoprotein B via a post-endoplasmic reticulum process, as well as improving the antiinflammatory properties of HDL in mice. Activity of this transfer protein in cerebrospinal fluid of patients with Alzheimer's disease is profoundly decreased and exogenous phospholipid transfer protein induces apolipoprotein E secretion by primary human astrocytes in vitro.

SUMMARY

Understanding the relationship between lipid transfer proteins and lipoprotein metabolism is expected to be an important frontier in the search for a therapy for atherosclerosis.

Use of total patient data for indirect estimation of reference intervals for 40 clinical chemical analytes in Turkey

In the present study we used patient data to calculate laboratory-specific indirect reference intervals. These values were compared with reference intervals obtained for a healthy group according to recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine and manufacturer suggestions. Laboratory results (422,919 records) from all subjects of 18–45years of age over a 1-year period were retrieved from our laboratory information system and indirect reference intervals for 40 common analytes were estimated using a modified Bhattacharya procedure. Indirect reference intervals for most of the biochemical analytes were comparable, with small differences in lower [alkaline phosphatase (ALP) (male), alanine aminotransferase (ALT), creatine kinase, iron (male), total iron-binding capacity, folic acid, calcium (female), lactate dehydrogenase (LDH), lipoprotein (a) [Lp(a)], thyroid-stimulating hormone (TSH), total triiodothyronine (T

Clin Chem Lab Med 2006;44:867–76.