Genetic variants of TNFSF4 and risk for carotid artery disease and stroke

In two independent human cohorts, the minor allele of SNP rs3850641 in TNFSF4 was significantly more frequent in individuals with myocardial infarction than in controls. In mice, Tnfsf4 expression is associated with increased atherosclerosis. The expression of TNFSF4 in human atherosclerosis and the association between genotype and cerebrovascular disease have not yet been investigated. TNFSF4 messenger RNA (mRNA) levels were significantly higher in human atherosclerotic lesions compared with controls (730 ± 30 vs 330 ± 65 arbitrary units, p < 0.01). TNFSF4 was mainly expressed by macrophages in atherosclerotic lesions. In cell culture, endothelial cells upregulated TNFSF4 in response to tumor necrosis factor alpha (TNF-α; 460 ± 110 vs 133 ± 8 arbitrary units, p < 0.001 after 6 h of stimulation). We analyzed the TNFSF4 gene in 239 patients who had undergone carotid endarterectomy and 138 matching controls from The Biobank of Karolinska Carotid Endarterectomies and Stockholm Heart Epidemiology Program cohorts and 929 patients and 1,382 matching controls from the Sahlgrenska Academy Study on Ischemic Stroke and Case Control Study of Stroke cohorts, limiting inclusion to patients with ischemic stroke. Participants were genotyped for the rs3850641 SNP in TNFSF4. Genotype associations were neither found with TNFSF4 mRNA levels nor with atherosclerosis associated systemic factors or risk for stroke. This study shows that TNFSF4 is expressed on antigen-presenting cells in human carotid atherosclerotic lesions but provides no evidence for an association of TNFSF4 gene variation with the risk for ischemic stroke.     

Genetic polymorphisms of alcohol metabolizing enzymes.

Alcohol metabolism is one of the biological determinants that can significantly influence drinking behavior and the development of alcoholism and alcohol-induced organ damage. Most ethanol elimination occurs by oxidation to acetaldehyde and acetate, catalyzed principally by alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Other ethanol oxidation pathways, including catalase and microsomal ethanol-oxidizing system (MEOS/CYP2E1), as well as the nonoxidative pathway (FAEES), which forms fatty acid ethyl esters, appear to play a minor role. The major alcohol metabolizing enzymes exhibit genetic polymorphism and ethnic variation. In this review recent advances in the understanding of the functional polymorphisms of ADH, ALDH and CYP2E1 and their metabolic, physiologic and clinical correlations are presented.     

ALOX5AP gene variants and risk of coronary artery disease: an angiography-based study

The aim of this study was to explore the role of variants of the gene encoding arachidonate 5-lipoxygenase-activating protein (ALOX5AP) as possible susceptibility factors for coronary artery disease (CAD) and myocardial infarction (MI) in patients with or without angiographically proven CAD. A total of 1431 patients with or without angiographically documented CAD were examined simultaneously for seven ALOX5AP single-nucleotide polymorphisms, allowing reconstruction of the at-risk haplotypes (HapA and HapB) previously identified in the Icelandic and British populations. Using a haplotype-based approach, HapA was not associated with either CAD or MI. On the other hand, HapB and another haplotype within the same region (that we named HapC) were significantly more represented in CAD versus CAD-free patients, and these associations remained significant after adjustment for traditional cardiovascular risk factors by logistic regression (HapB: odds ratio (OR) 1.67, 95% confidence interval (CI) 1.04-2.67; P=0.032; HapC: OR 2.41, 95% CI 1.09-5.32; P=0.030). No difference in haplotype distributions was observed between CAD subjects with or without a previously documented MI. Our angiography-based study suggests a possible modest role of ALOX5AP in the development of the atheroma rather than in its late thrombotic complications such as MI.     

Impact of inflammation,gene variants,and cigarette smoking on coronary artery disease risk

Inflammation Research - The role of inflammation in coronary artery disease (CAD) pathogenesis is well recognized. Moreover, smoking inhalation increases the activity of inflammatory mediators...     

Genetic variants of the class A scavenger receptor gene are associated with coronary artery disease in Chinese

The class A scavenger receptor,encoded by the macrophage scavenger receptor 1(MSR1) gene,is a pattern recognition receptor(PPR) primarily expressed in macrophages.It has been reported that genetic polymorphisms of MSR1 are significantly associated with the number of diseased vessels and coronary artery narrowing greater than 20% in Caucasians.However,whether it links genetically to coronary artery disease(CAD) in Chinese is not defined.Here,we performed an independent case-control study in a Chinese population consisting of 402 CAD cases and 400 controls by genotyping ten single nucleotide polymorphisms(SNPs) of MSR1.We found that rs416748 and rs13306541 were significantly associated with an increased risk of CAD with per allele odds ratio(OR) of 1.56 [95% confidence interval(CI) = 1.28-1.90;P < 0.001] and 1.70(95% CI = 1.27-2.27;P < 0.001),respectively.Our results indicate that genetic variants of MSR1 may serve as predictive markers for the risk of CAD in combination with traditional risk factors of CAD in Chinese population.     

Genetic risk for coronary artery disease in individuals with or without type 2 diabetes

Given that a substantial proportion of individuals with coronary artery disease (CAD) also have type 2 diabetes, it is important to identify genes that confer susceptibility to CAD independently in subjects with type 2 diabetes and in those without this condition. A large-scale association study was performed to identify genes that confer susceptibility to CAD in either the absence or presence of type 2 diabetes. The study population comprised 5207 unrelated Japanese individuals, including 3085 subjects with CAD and 2122 controls. Among all subjects, 1704 individuals had type 2 diabetes and 3503 individuals did not have this condition. The genotypes for 33 polymorphisms of 27 candidate genes were determined with a fluorescence- or colorimetry-based allele-specific DNA primer-probe assay system. Multivariate logistic regression analysis with adjustment for age, body mass index, and the prevalence of smoking, hypertension, hypercholesterolemia, and hyperuricemia revealed that the following polymorphisms were significantly (P < 0.005) associated with CAD: the 1019C -->T of the connexin 37 gene for men with type 2 diabetes; the 2445G -->A in the fatty acid-binding protein 2 gene for women with this condition; the -863C-->A in the tumor necrosis factor-alpha gene, the -219G-->T in the apolipoprotein E gene, the 1019C-->T in the connexin 37 gene for men without type 2 diabetes; and the -482C-->T in the apolipoprotein C-III gene for women without this condition. Genotyping of these polymorphisms may prove informative for assessment of the genetic risk for CAD in the absence or presence of type 2 diabetes.     

Role of plasma homocysteine and lipoprotein (a) in coronary artery disease

This study looks at the possible role of some non-traditional risk factors for premature coronary artery disease (CAD) and assesses the presence of relationship between these factors and the traditional cardiovascular risk factors. The study subjects (n=45) are divided into three groups comprising 15 premature CAD patients without traditional cardiovascular risk factors (group I); 15 premature CAD patients with one or more traditional cardiovascular risk factors (group II); and 15 healthy normal control subjects matched for age and sex (group III). Estimation of plasma homocysteine (Hcy) and plasminogen activator inhibitor-1 (PAI-1) is performed by enzyme-linked immunosorbent assay (ELISA); plasma folic acid by radioimmunoassay; plasma lipoprotein a (Lpa) by turbidimetry; and plasma lipids by colorimetry. Results showed a significant association between elevated Hcy and low folate levels and premature CAD in both patient groups. Also, a significant association was seen between elevated PAI-1 and CAD in the two patient groups, and between CAD and high levels of Hcy and triglycerides, as well as a low level of high-density lipoprotein cholesterol. Lpa showed significant association with premature CAD only in group II. Thus, Hcy, folic acid and PAI-1 might serve as independent risk factors for premature CAD in patients both with and without traditional coronary risk factors. However, Lpa might confer an additional coronary risk factor only in the presence of traditional risk factors.     

Haemochromatosis gene mutations and risk of coronary artery disease

The identification of mutations in the haemochromatosis gene (HFE) (C282Y and H63D) provides the unique opportunity to test whether genetic variants that are associated with tissue iron accumulation may influence the risk of coronary atherosclerosis. To this aim the prevalence of C282Y and H63D mutations was determined in 174 patients with angiographically documented CAD (>50% stenosis) and history of MI, 187 healthy free-living individuals and 142 blood donors. C282Y and H63D mutations were not found to be more frequent in coronary patients as compared to controls. Moreover, these HFE variants were unrelated to the severity of coronary atherosclerosis. These findings did not provide evidence of an association between HFE mutations and the presence of coronary atherosclerosis or its major ischaemic complications, thus indicating that HFE mutations are poor genetic markers of coronary risk.     

Lipid peroxidation and antioxidant enzymes in coronary and peripheral artery disease

There is a strong co-relation in between the levels of blood lipids in patients of different subgroups of CAD, however this is not present in the case of subgroups of patients in PAD. Moreover levels of MDA and antioxidant enzymes are also significantly altered in the subgroups of CAD but the correlation is weak in that of PAD. Thus these values may serve as a clinical support for experimental data and supplementary information regarding atheromatous disease.     

Thermolabile methylenetetrahydrofolate reductase C677T polymorphism and homocysteine are risk factors for coronary artery disease in Moroccan population

Increased plasma total homocysteine (tHcy) levels have been shown to be a risk factor for coronary artery disease (CAD). The common methylenetetrahydrofolate reductase C677T (MTHFR C677T) polymorphism has been reported to be a strong predictor of mild hyperhomocysteinaemia (HHcy). We assessed whether this mutation was associated with increased risk of CAD and plasma levels of tHcy. We also evaluated interactions between this polymorphism, mild elevated tHcy levels and conventional risk factors of CAD. Method. Using PCR-RFLP analysis, we studied the frequency of the C677T genotypes and its effect on CAD and on tHcy concentrations in 400 subjects without and with CAD angiographically confirmed. There were 210 subjects with CAD and 190 subjects without CAD. Results. The frequencies of the C677T genotypes were 53% (59.5% in controls versus 48.1% in cases), 34.8% (32.1 in controls versus 37.1 in cases), and 11.8% (8.4% in controls versus 14.8% in cases), respectively, for 677CC, 677CT, and 677TT. The genotype frequencies were significantly different between case and control groups (P < .05). The 677T allele enhances the risk of CAD associated to HHcy (P < .01). In multivariate analysis models, MTHFR C677T polymorphism effect on CAD was masked by other risk factors. HHcy was only and independently influenced by MTHFR polymorphism and smoking habits, and it is a strong predictor of CAD independently of conventional risk factors. Conclusion. Our data suggest that HHcy is strongly and independently associated to CAD risk increase; and MTHFR C677T polymorphism and smoking habits were the main predictors of tHcy levels. The CAD risk increase is mainly associated with mild HHcy in 677TT, whereas in 677CT and 677CC it is mainly associated with the conventional risk factors.     

Genetic variation and nutrition in relation to coronary artery disease

There is evidence that coronary artery disease (CAD), hypertension, diabetes mellitus (DM) and hyperlipidemia develop due to interaction of genetic and environmental factors during transition from poverty to affluence. Rapid transition in diet and lifestyle factors may influence heritability of the variant phenotypes that are dependent on the nutrient environment for their expression. We are beginning to recognize the interaction of specific nutrients with the genetic code possessed by all nucleated cells. In the next millennium, the physician may be able to make nutrient intake recommendations not on physical characteristics but on the basis of the individual's phenotypic expression for health while suppressing his phenotypic expression for disease. We have demonstrated an increased susceptibility to CAD, diabetes, central obesity, hyperinsulinemia and lipoprotein(a) excess in Indians in younger age groups indicating a genetic predisposition to these problems due to interaction of gene and environment. Lipoprotein(a) is a genetic risk factor for CAD, diabetes and stroke and it is higher in South Indians than North Indians. Antioxidant vitamins, coenzyme Q10 and n-3 fatty acids may have a beneficial influence whereas linoleic acid, saturated fat and sugars may have adverse effects on phenotypic expression. There is significant evidence that genes are involved in determining enzymes, receptors, cofactors, structural components involved in regulation of blood pressure, the metabolism of lipids, lipoproteins and inflammatory and coagulation factors that are involved in determining an individual's risk. Majority of these genes are polymorphic. While some genes respond to nutritional modulation, others may not indicate any response.     

Polymorphisms in the CBS gene associated with decreased risk of coronary artery disease and increased responsiveness to total homocysteine lowering by folic acid

Elevated total plasma homocysteine (tHcy) is an established risk factor for the development of vascular disease and neural tube defects. Total homocysteine levels can be lowered by folic acid supplements but individual response is highly variable. In this case-control study, involving 142 coronary artery disease (CAD) patients and 102 controls, we have typed six genetic polymorphisms in three homocysteine metabolizing genes and examined their relationship to the incidence of CAD, tHcy levels, and lowering of tHcy levels in response to folic acid supplementation. We found that two single nucleotide polymorphisms in the cystathionine beta synthase (CBS) gene, 699C --> T and 1080T --> C, are associated with decreased risk of CAD and increased responsiveness to the tHcy lowering effects of folic acid. Individuals homozygous for 699T were significantly underrepresented in CAD patients as compared to controls (4.9% vs 17.3%, P = 0.0015), as were individuals homozygous for the 1080C (29.6% vs 44.2%, P = 0.018). Additionally, 699T and 1080C homozygous individuals were the most responsive to folate supplementation. 699T homozygotes lowered tHcy levels 13.6% on average, compared to 4.8% lowering in 699C homozygotes (P = 0.009), while 1080C homozygotes lowered 12.9% compared to just 2.7% for 1080T homozygotes (P = 0.005). The two polymorphisms in CBS are third codon changes and would not be predicted to affect the underlying protein. However, there is strong linkage disequilibrium between these two positions, suggesting that they may also be linked to other as yet unidentified polymorphisms within the CBS gene. These observations suggest that specific CBS alleles are a risk factor for the development of vascular disease and that genetic information could be predictive of individual response to folic acid supplementation.     

Anger and coronary calcification in individuals with and without risk factors of coronary artery disease

The authors investigated the relationship between anger and the calcification of the coronary artery in individuals with and without risk factors for coronary artery disease in Korea. Sixty-one subjects with risk factors of coronary artery disease and 31 subjects without risk factors were enrolled in this study. Electron Beam Computed Tomography was used to measure the calcium level of coronary artery. The anger expression scale was used to measure the anger levels. The anxiety, depression, hostility, and somatization subscales of the symptom checklist-90-revised (SCL-90-R) and the global assessment of recent stress (GARS) scale were used to assess the psychopathology and perceived stress. The logistic regression analysis results showed that only the anger-total score was significantly associated with the coronary calcification regardless of the risk factors. These results suggest that anger plays an important role in the calcification of the coronary artery.     

Werner syndrome protein 1367 variants and disposition towards coronary artery disease in Caucasian patients

The leading causes of death for individuals with Werner syndrome (WS) are myocardial infarction (MI) and stroke. The WS gene encodes a nuclear protein with both helicase and exonuclease activities. While individuals with WS have mutations that result in truncated, inactive proteins, several sequence variants have been described in apparently unaffected individuals. Some of these gene polymorphisms encode non-conservative amino acid substitutions, and it is expected that the changes would affect enzyme activity, although this has not been determined. Two research groups have studied the Cys/Arg 1367 polymorphism (located near the nuclear localization signal) in healthy and MI patients. Their results suggest that the Arg allele is protective against MI. We have characterized the Cys (C) and Arg (R) forms of the protein and find no notable difference in helicase and nuclease activities, or in nuclear/cytoplasmic distribution. The frequency of the C/R alleles in healthy individuals and subjects with coronary artery disease (CAD) drawn from the Baltimore Longitudinal Study of Aging (BLSA) was also examined. There was no indication that the R allele was protective against CAD. We conclude that the C/R polymorphism does not affect enzyme function or localization and does not influence CAD incidence in the BLSA cohort.