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Interaction among 5,10 methylenetetrahydrofolate reductase, plasminogen activator inhibitor and endothelial nitric oxide synthase gene polymorphisms predicts the severity of coronary artery disease in Turkish patients
Abstract
Genetic factors play a role in the onset of coronary artery disease. The objective of our study is to evaluate the single locus and combined effects of three different genetic polymorphisms (methylenetetrahydrofolate reductase C677T polymorphism, plasminogen activator inhibitor 4G/5G polymorphism, and endothelial nitric oxide synthase 3-27 base pairs repeat polymorphism) on the presence and extent of coronary artery disease in patients with early-onset coronary artery disease.
DNA samples were obtained from 102 consecutive patients with symptoms resulting from early-onset coronary artery disease documented by coronary angiography. The severity of coronary artery disease in patients was stratified into three groups as one, two, or three-vessel coronary artery disease. The control group was selected from older subjects with a recent and negative cardiac work-up. Information on standard risk factors was collected. Multifactor dimensionality reduction analysis was performed to seek a model of coronary artery disease based on these three genetic polymorphisms.
Single-locus effects of the three polymorphisms were not significantly related to the presence or severity of coronary artery disease. When gene-gene interactions were studied, however, the severity of disease was related to the frequency of high-risk alleles, yet advanced analysis did not detect a significant genetic model for coronary artery disease in these patients based on these three genetic polymorphisms.
These three genetic polymorphisms are susceptibility loci and genotypes of these genes are neither necessary nor sufficient for the coronary artery disease to occur, but coexistence of high-risk alleles may increase the severity of coronary artery disease.
... Controls were mainly matched in terms of gender and age. Fourteen studies were hospital-based [16][17][18]20,21,25,28,[37][38][39][40]42,43,45], and 20 were population-based [9,[12][13][14][15]19,22,23,26,27,[29][30][31][32][33][34]36,41,46,47]. Thirty studies were performed using <500 subjects in the case group [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]29,[33][34][35][36][38][39][40][41][42][43][44][45][46][47] and 33 were conducted with <500 subjects in the control group [9,[12][13][14][15][17][18][19][20][21][22][23][24][25][26][27][28][29]32,[34][35][36][37][38][39][40][41][42][43][44][45][46][47]. ...
... Fourteen studies were hospital-based [16][17][18]20,21,25,28,[37][38][39][40]42,43,45], and 20 were population-based [9,[12][13][14][15]19,22,23,26,27,[29][30][31][32][33][34]36,41,46,47]. Thirty studies were performed using <500 subjects in the case group [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]29,[33][34][35][36][38][39][40][41][42][43][44][45][46][47] and 33 were conducted with <500 subjects in the control group [9,[12][13][14][15][17][18][19][20][21][22][23][24][25][26][27][28][29]32,[34][35][36][37][38][39][40][41][42][43][44][45][46][47]. Furthermore, there were 20 studies of CAD [9,18,20,22,23,25,29,30,32,[34][35][36][37][38][39][40][42][43][44]46], four of CHD [17,[26][27][28], three of acute myocardial infarction [15,19,45], six of myocardial infarction (MI) [12][13][14]16,31,41], and four of acute coronary syndrome [21,24,33,47]. ...
... Fourteen studies were hospital-based [16][17][18]20,21,25,28,[37][38][39][40]42,43,45], and 20 were population-based [9,[12][13][14][15]19,22,23,26,27,[29][30][31][32][33][34]36,41,46,47]. Thirty studies were performed using <500 subjects in the case group [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]29,[33][34][35][36][38][39][40][41][42][43][44][45][46][47] and 33 were conducted with <500 subjects in the control group [9,[12][13][14][15][17][18][19][20][21][22][23][24][25][26][27][28][29]32,[34][35][36][37][38][39][40][41][42][43][44][45][46][47]. Furthermore, there were 20 studies of CAD [9,18,20,22,23,25,29,30,32,[34][35][36][37][38][39][40][42][43][44]46], four of CHD [17,[26][27][28], three of acute myocardial infarction [15,19,45], six of myocardial infarction (MI) [12][13][14]16,31,41], and four of acute coronary syndrome [21,24,33,47]. ...
A variety of studies have suggested that the 4b/a polymorphism in the endothelial nitric oxide synthase (eNOS) was associated with coronary artery disease (CAD) risk. However, the data remain conflicting. The aim of the present meta-analysis was to estimate the overall association between risk of CAD and eNOS 4b/a polymorphism. Case-control, cohort or cross-sectional studies evaluating the association between eNOS 4b/a polymorphism and CAD susceptibility were systematically identified in PubMed up to 31 October 2013. Pooled odds ratios (OR) and corresponding 95% confidence intervals (CIs) were calculated to assess the association in overall and subgroup analyses. A total of 10,617 cases and 8302 controls from 37 studies were included in the study. The results of overall analysis revealed significant positive associations between CAD risk and eNOS 4b/a polymorphism in homozygote comparisons (OR = 1.47, 95% CI = 1.16-1.87), heterozygote comparisons (OR = 1.14, 95% CI = 1.02-1.27) and dominant models (OR = 1.18, 95% CI = 1.06-1.33). In subgroup analyses, similar associations were identified in African individuals, as determined using population-based source subgroups and noted in small-and-moderate sample size subgroups (case sample size or control sample size <500). The current meta-analysis revealed that eNOS 4b/a polymorphisms could be a risk factor for developing CAD, particularly in African populations and population-based subgroups.
... The index case was genotyped for the single base pair guanine deletion/insertion (4G/5G) polymorphism located at position -675 of the PAI-1 promoter as described previously [18]. PAI 4G/5G polymorphism was analyzed by polymerase chain reaction-restriction fragment length polymorphism. ...
... 4G/4G homozygous polymorphism in the PAI-1 promoter was the most common genotype (53 %) (Fig. 1); 4G allele frequency was calculated to be 74 %. Even though we had a small sample size, we observed increased 4G allele frequency among family members compared to prior observations from Turkish population [18]. ...
Vitiligo is a common skin condition with a complex pathophysiology characterized by the lack of pigmentation due to melanocyte degeneration. In this study, we investigated PAI-1 antigen (Ag) and activity levels in a 34 year old male with extensive vascular disease, alopecia areata and vitiligo. Fasting PAI-1 Ag and activity levels were measured at 9 a.m. in the subject and family members. Both PAI-1 Ag (67 ± 38 vs. 18.6 ± 6.5 ng/ml, P < 0.001) and specific activity (15.8 ± 10.0 vs. 7.6 ± 6.0 IU/pmol, P < 0.04) levels of PAI-1 were moderately elevated in subjects compared to the controls. PAI-1 kinetic studies demonstrated a markedly enhanced stability of plasma PAI-1 activity in the family members. Specific activity at 16 h was significantly higher than expected activity levels (0.078 ± 0.072 vs. 0.001 ± 0.001 IU/ng/ml, P < 0.001). While the exact mechanism of increased stability of PAI-1 activity in vitiligo is not known, it is likely due to post-translational modifications or increased binding affinity for a stabilizing cofactor. In conclusion, enhanced stability of PAI-1 may contribute to the pathophysiology of vascular disease and associated melanocyte degeneration. Systemic or local treatment with PAI-1 inhibitors may offer a potential treatment alternative to the near orphan status for vitiligo drug development.
... While 20% of LV patients displayed 5G/5G genotype, more than half of the patients (55%) were heterozygote (4G/5G) and 25% were homozygote (4G/4G) for the PAI-1 gene promoter (Fig. 3); 4G allele frequency was calculated to be 52.5%. Even though we had a small sample size, we noted that the genotype frequencies were similar among LV patients compared to prior observations from Turkish subjects [18]. We did not observe significant differences in the PAI-1 Ag and activity levels between the three genotype groups. ...
... Livedoid vasculopathy lesions responded to t-PA infusion in a patient with 4G/4G genotype [11]. We observed that genotype frequencies were similar among LV patients compared to prior observations from Turkish subjects [18] without any significant difference in PAI-1 Ag and activity between genotype groups. Even though we did not analyze the glycosylation pattern of PAI-1, tissue-specific PAI-1 gene expression and glycosylation pattern may potentially explain the enhanced PAI-1 activity in patients with livedoid vasculaopathy [25]. ...
Livedoid vasculopathy (LV) is a chronic, recurrent, painful cutaneous disease with distinctive clinical features and an uncertain etiology. The skin lesions are recognizable by focal purpura, depigmentation and shallow ulcers. Thrombophilic conditions occur frequently in patients with LV. While no definitive treatment exists for LV, smoking cessation, antiplatelet therapy, immunosuppressive treatment, and anabolic steroids are often included in the therapeutic ladder. Recently, a possible link between LV and impaired fibrinolysis was established as cutaneous LV lesions responded to tissue plasminogen activator (t-PA) infusion suggesting that inhibition of the fibrinolysis through plasminogen activator inhibitor-1 (PAI-1) activity may determine the disease course in patients with LV. In this study, we investigated PAI-1 antigen (Ag) and activity levels in 20 patients with biopsy proven LV (mean age 26 ± 11, M/F = 7/13, median disease duration 3.5 years). All patients received antiplatelet treatment with aspirin and/or dipyrimadole and 14 patients received anabolic steroids or immunosuppressive treatment. Fasting PAI-1 Ag and activity levels were measured at 9 AM in all patients. Both Ag (34 (26) ng/ml) (median (interquartile range)) and specific activity (17 (23) IU/fmole) levels of PAI-1 were moderately elevated in LV patients compared to the controls, however, PAI-1 kinetic studies demonstrated markedly enhanced stability of PAI-1 activity in plasma from patients with LV. Specific activity at 16 h was significantly higher than expected specific activity levels (7 (11) vs. 0.07 (0.09) IU/fmole, P
... MDR was designed to detect gene-gene interactions in the presence or absence of main effects in case-control studies in human genetics [Hahn et al., 2003;Ritchie et al., 2001]. MDR has been shown to have high power to detect interactions in a wide range of simulated data Ritchie et al., 2003a;Velez et al., 2007] and has identified interactions in common complex diseases such as multiple sclerosis [Brassat et al., 2006;Motsinger et al., 2007], coronary artery disease [Agirbasli et al., 2006], and diabetic nephropathy [Hsieh et al., 2006]. MDR has previously been described in detail [Hahn et al., 2003;Ritchie et al., 2001]. ...
... The success of MDR in all the models simulated is not surprising, given its many previous successes in both real and simulated data [Agirbasli et al., 2006;Cho et al., 2004;Hsieh et al., 2006; Ritchie et al., 2001Ritchie et al., , 2003a. The success of GENN for main effect and two-locus models was also expected, given its previous successes in real and simulated data [Motsinger et al., 2006a,b,c;Motsinger-Reif et al., 2008a], but its poor performance with the three-locus models was surprising. ...
The explosion of genetic information over the last decade presents an analytical challenge for genetic association studies. As the number of genetic variables examined per individual increases, both variable selection and statistical modeling tasks must be performed during analysis. While these tasks could be performed separately, coupling them is necessary to select meaningful variables that effectively model the data. This challenge is heightened due to the complex nature of the phenotypes under study and the complex underlying genetic etiologies. To address this problem, a number of novel methods have been developed. In the current study, we compare the performance of six analytical approaches to detect both main effects and gene-gene interactions in a range of genetic models. Multifactor dimensionality reduction, grammatical evolution neural networks, random forests, focused interaction testing framework, step-wise logistic regression, and explicit logistic regression were compared. As one might expect, the relative success of each method is context dependent. This study demonstrates the strengths and weaknesses of each method and illustrates the importance of continued methods development.
... (Table 3 and Figures 4, S5 and S6) Subgroup analysis. A total of 20 studies from European, [2,27,33,37,39,54,55,57,58,61,64,91,93,99-105] 8 from Middle Eastern,[34,76,[106][107][108][109][110][111] 10 from Asian,[11,22,35,36,80,82,112- 115] 2 from Asian-Indian[90,116] and 3 from African[57,98,104] group were included for subgroup analysis. ( ...
Several association studies of endothelial nitric oxide synthase (NOS3) gene polymorphisms with respect to coronary artery disease (CAD) have been published in the past two decades. However, their association with the disease, especially among different ethnic subgroups, still remains controversial. This prompted us to conduct a systematic review and an updated structured meta-analysis, which is the largest so far (89 articles, 132 separate studies, and a sample size of 69,235), examining association of three polymorphic forms of the NOS3 gene (i.e. Glu298Asp, T786-C and 27bp VNTR b/a) with CAD. In a subgroup analysis, we tested their association separately among published studies originating predominantly from European, Middle Eastern, Asian, Asian-Indian and African ancestries. The pooled analysis confirmed the association of all the three selected SNP with CAD in three different genetic models transcending all ancestries worldwide. The Glu298Asp polymorphism showed strongest association (OR range = 1.28-1.52, and P<0.00001 for all comparisons), followed by T786-C (OR range = 1.34-1.42, and P<0.00001 for all comparisons) and 4b/a, (OR range = 1.19-1.41, and P≤0.002 for all comparisons) in our pooled analysis. Subgroup analysis revealed that Glu298Asp (OR range = 1.54-1.87, and P<0.004 for all comparisons) and 4b/a (OR range = 1.71-3.02, and P<0.00001 for all comparisons) have highest degree of association amongst the Middle Easterners. On the other hand, T786-C and its minor allele seem to carry a highest risk for CAD among subjects of Asian ancestry (OR range = 1.61-1.90, and P≤0.01 for all comparisons).
... Generally, it can be acknowledged that in many cases, haplotyping has been found to be more meaningful than individual variants. One study involving methylenetetrahydrofolate reductase C677T, plasminogen activator inhibitor 4G/5G, and endothelial nitric oxide synthase 3-27 base pair repeat polymorphism in patients with early-onset CAD suggested the coexistence of high-risk alleles as augmenting the severity of the disease 128 . These results are a manifestation of the relevance of the concept of multilocus and multi-gene effects in complex diseases, such as CAD. ...
... [33][34][35] MDR has also been used to identify interactions in common complex diseases. [36][37][38][39] MDR is a non-parametric, model-free approach, making it a unique tool for identifying interactions. MDR categorizes all genetic data into 2 groups, "high risk" and "low risk", by comparing all single loci and all multilocus combinations and then categorizing each genotype as either "high risk" or "low risk" on the basis of the ratio of cases to controls having that genotype. ...
Oxidative stress may be an important pathogenic mechanism in the obesity and metabolic syndrome. The aims of this study was to assess the possible association between the oxidative stress related Glutathione S-Transferase genes (GST-M1, GST-T1, and GST-P1) variants and the olanzapine-induced weight gain in Korean schizophrenic patients.
We categorized 78 schizophrenic patients into two groups the more than 7% weight gain from baseline (weight gain >/=7%) and the less weight gain (weight gain <7%) groups according to weight change between before and after long-term olanzapine treatment (440+/-288 days). All participants were genotyped for the GST-M1, GST-T1 and GST-P1 genes. Differences in allele frequencies between cohorts with different body weight changes were evaluated by a chi-square analysis and Fisher's exact test. The multifactor dimensionality reduction (MDR) approach was used to analyze gene-gene interactions.
Mean body weight gain was 5.42 kg. There was no difference in the null genotype distribution of GST-M1 and -T1 between subjects with body weight gain >/=7% compared to subjects with body weight gain <7% (p>0.05). No significant difference in GST-P1 genotype and allele frequencies were observed between the groups (p>0.05). MDR analysis did not show a significant interaction between the three GST gene variants and susceptibility to weight gain (p>0.05).
These findings do not support a relationship between the genetic variants of three GST genes (GST-M1, -T1 and -P1) and weight gain in Korean schizophrenic patients receiving olanzapine treatment.
The aim of the paper is to present the results of the VNTR gene polymorphism genetic variants molecular typing for
endothelial nitric oxide synthase (eNOS) in human population of Tuzla Canton. Based on the analysis of the distribution of
eNOS gene genotypes in the total sample of respondents, the highest frequency was recorded for the (b/b) genotype, which
was 73.0%. For the heterozygous (a/b) genotype of the eNOS gene, a frequency of 24.0% was determined, and a frequency
of 3.0% was recorded for the (a/a) genotype. The research resulted in a database of local and global significance, namely,
the incorporation of these data into the existing regional and European genetic database.
The aim of the current study was to evaluate the association of PAI-1 4G/5G polymorphism with coronary artery disease (CAD) risk using a meta-analysis.
All eligible studies were identified through a search of PubMed, EMBASE, China National Knowledge Infrastructure (CNKI), Database of Chinese Scientific and Technical Periodicals, and China Biology Medical literature database (CBM) before June 2014. The association between the PAI-1 4G/5G polymorphism and CAD risk was estimated by odds ratio (OR) and 95% confidence interval (CI).
A total of 72 studies including 23557 cases and 21526 controls were eventually collected. The PAI-1 4G/5G polymorphism was significant associated with CAD risk in overall population (OR=1.19, 95% CI 1.10-1.28, P < 0.00001). The combination of adjusted ORs for CAD was 1.20 (95% CI 1.03-1.40, P=0.02). This polymorphism was associated with CAD risk in Caucasians (OR=1.10, 95% CI 1.02-1.19, P=0.01) and Asians (OR=1.46, 95% CI 1.21-1.75, P < 0.0001). This polymorphism significantly increased MI risk (OR=1.15, 95% CI 1.06-1.25, P=0.001). In the subgroup analysis by age, this polymorphism was significantly associated with early-onset CAD risk (OR=1.21, 95% CI 1.02-1.43, P=0.03). In the gender subgroup analyses, a statistically significant association was found in male CAD patients (OR=1.10, 95% CI 1.01-1.20, P=0.04). Both T2DM patients and non-T2DM patients carrying 4G allele showed increased CAD risks (OR=2.23, 95% CI 1.27-3.92, P=0.005 and OR=1.64, 95% CI 1.19-2.25, P=0.002, respectively).
This meta-analysis suggested that PAI-1 4G/5G polymorphism was a risk factor for CAD.
Objective:
To investigate the interaction between polymorphisms and environment factors in age related cataract (ARC).
Methods:
Population-based case-control study. All of 448 cataract cases were selected from cataract eye database and 248 controls were recruited from Funing county. All 18 single nucleotide polymorphism (SNPs) of WRN, OGG1, BLM and ERCC6 genes were genotyped using real-time fluorescent quantitative PCR. The possible risk of ARC was estimated by unconditional Logistic regression. The interaction effects between gene-gene and gene-environment were evaluated by use of multifactor dimensionality reduction (MDR).
Results:
Risk of ARC in illiterate group was significantly increased (OR = 1.53, P < 0.05), compared to no illiterate group. The risk of cataract in farmers was significantly high with ORs of 3.75. Long exposure to sunlight may increase cataract risk. Factors such as smoking, drinking, hypertension had no relationship with ARC (P > 0.05). WRN-rs11574311 was still associated with ARC with statistical significance after Bonferroni correction (OR = 1.98, Pa<0.018). There was no evidence for any association at a significance level of P < 0.05 for the remaining alleles. MDR analysis showed a significant interaction model among the six factors: education, solar radiation, WRN-rs11574311, WRN-rs1801195, WRN-rs4733220 and BLM-rs17273206 (consistency inspection accuracy of 0.683 on average, cross validation at 10/10, P = 0.005). Logistic regression model showed that the "high-risk" individuals had a significantly increased risk of ARC, compared to those "low- risk" individual classified by the MDR mode mentioned above(OR = 5.51, P < 0.05).
Conclusion:
WRN-rs11574311 allele was the risk factor for ARC, and individuals who carried WRN-rs1801195, WRN-rs4733220 and BLM-rs17273206 allele and low level of education, long sunlight time significantly increased the risk of the ARC.
As a leading cause of mortality, coronary artery disease is on the focus of genetic research as a complex trait. Although predictive genetic testing for cardiovascular diseases is on the counter, it is still hard to aggregate information from multiple genetic variants, environmental factors and family history into a single score. Every susceptibility allele provides small contribution to disease formation. Biomarkers play a role in various metabolic pathways. Genetic information and data depend heavily on probabilities. This should be clearly explained by genetic counselor to the patient and relatives who are looking for certain answers. Presence of susceptibility alleles can be a source of anxiety and it may result as a reduced self-confidence in ability to change health behavior. Complex diseases set a new stage to study novel techniques that can elucidate interactions among genetic, environmental and ethnic factors. The cookbook approach to treat a complex disease can often be misleading. Future studies may provide personalized information, which can improve the outcome of standardized treatments. As knowing one's own genetic risk is becoming a task for the responsible individual, it surely will add new challenges to ethical framework. Publicly marketing genetic tests for complex diseases raises ethical concerns. To avoid discriminatory use of genetic information; genetic risk scoring, therapeutic process, ethical policies must have a multifaceted progress. In this review, we summarized the attempts to resolve ethical issues related to genetic testing in complex diseases to resolve patient autonomy with individual responsibility and to aim the patient beneficence and confidentiality.
Association studies in the Turkish population have investigated the single locus effects of different gene polymorphisms on coronary artery disease (CAD). CAD is a complex polygenic disease that involves complex interactions among multiple genetic and environmental conditions.
We evaluated associations of five candidate genetic polymorphisms (methylene tetrahydrofolate reductase C677T, plasminogen activator inhibitor 4G/5G, endothelial nitric oxide synthase (eNOS) 3-27 base pair repeat, insertion, or deletion of a 287 bp Alu repeat sequence polymorhism of angiotensin I converting enzyme, and paraoxonase Gln192Arg PON1 polymorphisms) with the presence and extent of early onset CAD.
DNA was isolated and amplified from 90 consecutive patients with angiographically proven early onset CAD (ages 41 ± 5 for men, 49 ± 7 for women) and also from 90 control subjects with no significant coronary obstruction angiographically (ages 42 ± 5 for men, 48 ± 6 for women). Multifactor dimensionality reduction (MDR) analysis was performed to identify a model of CAD based on both genetic and conventional risk factors.
MDR analysis detected a significant model with four genes (prediction success ∼ 61%, p = 0.03). When the total number of the conventional risk factors is analysed with the candidate polymorphisms, a different model is identified that includes three of the four genes from the above model and achieves a similar prediction of CAD as the gene only model.
These data indicate that gene-gene and gene-environmental risk interactions form significant models in predicting early onset CAD.
Previous case-control studies have suggested that the endothelial nitric oxide synthase (eNOS) gene polymorphisms (G894T, 4b/a, T-786C) are associated with coronary artery disease (CAD). However, other studies do not confirm these relationships. The objective was to assess these relationships using meta-analysis.
Databases, including Pubmed and Embase, were searched to access the relevant genetic association studies up to July 2009.
The meta-analysis included 56 studies, consisting of 23 studies for G894T, 19 for 4b/a and 14 for T-786C. For the allelic analysis of the G894T variant, all studies showed a positively significant association (OR = 0.83, p = 0.004). For the genotypic analysis, the combined studies of the T allele showed significance (OR = 1.57, p = 0.003). For the allelic analysis of the T-786C variant, all studies showed an obviously significant association (OR = 0.79, p = 0.0007), reflected in both non-Asian and Asian studies. For the genotype analysis, combined studies of the C allele showed significance (OR = 0.72, p = 0.0001). Moreover, non-Asian studies showed significant results. For the analysis of the 4b/a variant, none of the studies showed significant results. No publication bias was found in the meta-analysis.
The synthesis of available evidence supports the fact that eNOS G894T andT-786C are associated with CAD.
We assessed the association between common variation at the SERPINE1 (PAI1) locus and myocardial infarction (MI). Haplotype-tagging polymorphisms, including the 4G/5G deletion/insertion polymorphism and seven single nucleotide polymorphisms, were analysed in a German sample containing 3,657 cases with MI and 1,211 controls. The association between the 4G/5G polymorphism and MI was examined in a meta-analysis of data extracted from 32 studies (13,267 cases/14,716 controls). In addition, the relation between the 4G/5G polymorphism and coronary diseases, comprising MI, coronary artery disease, coronary heart disease, or the acute coronary syndrome, was assessed in a combined analysis enclosing 43 studies (17,278 cases/18,039 controls). None of the tagging polymorphisms was associated with MI in the present sample (p <or= 0.34). The adjusted odds ratio (OR) for 4G allele carriers was 1.02 (95% confidence interval [CI] 0.87-1.19) compared to the 5G5G genotype. None of 13 common (frequency >1.0%) 8-marker haplotypes was related to the risk of MI. In a meta-analysis specifically addressing the association with MI, no elevated risk was found in the carriers of the 4G allele (OR 1.07, 95% CI 0.99-1.16; p = 0.11). A more general combined analysis of coronary diseases showed a marginally increased risk in 4G allele carriers (OR 1.08, 95% CI 1.00-1.16; p = 0.044). In essence, tagging polymorphisms, including the 4G/5G polymorphism, and common haplotypes of the SERPINE1 gene region were not associated with MI in a German sample, and no compelling evidence was obtained for a relationship of the 4G/5G polymorphism to MI and coronary atherosclerosis in a meta-analysis.
Nitric oxide (NO) is the major mediator in the regulation of vascular homeostasis. It is synthesized by endothelium from arginine with the catalytic help of endothelial NO synthase (eNOS). Polymorphisms in the eNOS gene have been associated inconsistently with many vascular diseases. Conflicting results may arise from ethnic variations, notably in control-case studies. Therefore, to obtain reliable information and improve the design of such genetic association studies, we examined the distribution of genetic alleles of 3 clinically relevant eNOS polymorphisms (the variable number of tandem 27-base pair [bp] repeats in intron 4, T-786C in promoter, and G894T in exon 7) in 300 healthy Turkish individuals with a mean age of 50.07 (SD 12.15) years (range, 22-78 years; 50.7% men and 49.3% women). The haplotype frequency was estimated and associations between 3 polymorphisms were evaluated. We discussed the similarity and differences in the distribution of alleles with other populations. The allele frequencies were 45.3%, 48%, and 62.7% for GG of exon 7, TT of promoter, and bb of intron 4 (wild types), respectively. The most common haplotype combines the wild-type alleles (G-T-b) for all 3 polymorphisms (estimated frequency, 37.6%). The linkage analysis between each pairwise combination showed specific associations between T-786C polymorphism in promotor and G894T polymorphism in exon 7 (positive D' value, +0.3387). No significant correlation was found in the genotype distribution of the 3 polymorphisms with age, sex, and obesity. Our eNOS gene allele distributions resemble those of Caucasians and white populations. Our data showed ethnic differences with other populations in the allele distribution of eNOS gene besides conserved distribution of these polymorphisms in Turkish population. This study produced a reference control data for the 3 eNOS polymorphisms in Turkish population and will be helpful in planning eNOS association studies in vascular disease.
Data from several studies suggest that oxidative stress may play a role in the pathophysiology of tardive dyskinesia (TD). Glutathione S-transferase (GST) enzymes play important roles in protecting cells against oxidative stress. In the present study, we investigated the hypothesis that polymorphisms in genes for these detoxifying enzymes can influence susceptibility to TD in patients with schizophrenia.
The GST-M1, GST-T1, and GST-P1 loci were analyzed by polymerase chain reaction (PCR)-based methods in 83 schizophrenic patients with TD and 126 schizophrenic without TD who were matched for antipsychotic drug exposure and other relevant variables. The multifactor dimensionality reduction (MDR) approach was used to analyze gene-gene interactions.
There were no significant differences in the distributions of the GST-M1, GST-T1, and GST-P1 genotypes between the TD and non-TD groups (p > 0.05). However, in comparison of the severity of TD among genotypes using Poisson regression showed that Ile/Ile genotype of GST-P1 had higher AIMS score compared to Ile/Val + Val/Val genotypes (X(2) = 7.13, p = 0.008). MDR analysis did not show a significant interaction between the three GST gene variants and susceptibility to TD (p > 0.05).
These results suggest that GST gene polymorphisms do not confer increased susceptibility to TD in patients with schizophrenia but TD severity might be related with GST-P1 variants.
Context
In observational studies, individuals with elevated levels of plasma
homocysteine tend to have moderately increased risk of coronary heart disease
(CHD). The MTHFR 677C→T polymorphism is a genetic
alteration in an enzyme involved in folate metabolism that causes elevated
homocysteine concentrations, but its relevance to risk of CHD is uncertain.Objective
To assess the relation of MTHFR 677C→T
polymorphism and risk of CHD by conducting a meta-analysis of individual participant
data from all case-control observational studies with data on this polymorphism
and risk of CHD.Data Sources
Studies were identified by searches of the electronic literature (MEDLINE
and Current Contents) for relevant reports published before June 2001 (using
the search terms MTHFR and coronary
heart disease), hand searches of reference lists of original studies
and review articles (including meta-analyses) on this topic, and contact with
investigators in the field.Study Selection
Studies were included if they had data on the MTHFR 677C→T genotype and a case-control design (retrospective or nested
case-control) and involved CHD as an end point. Data were obtained from 40
(34 published and 6 unpublished) observational studies involving a total of
11 162 cases and 12 758 controls.Data Extraction
Data were collected on MTHFR 677C→T genotype,
case-control status, and plasma levels of homocysteine, folate, and other
cardiovascular risk factors. Data were checked for consistency with the published
article or with information provided by the investigators and converted into
a standard format for incorporation into a central database. Combined odds
ratios (ORs) for the association between the MTHFR 677C→T
polymorphism and CHD were assessed by logistic regression.Data Synthesis
Individuals with the MTHFR 677 TT genotype
had a 16% (OR, 1.16; 95% confidence interval [CI], 1.05-1.28) higher odds
of CHD compared with individuals with the CC genotype. There was significant
heterogeneity between the results obtained in European populations (OR, 1.14;
95% CI, 1.01-1.28) compared with North American populations (OR, 0.87; 95%
CI, 0.73-1.05), which might largely be explained by interaction between the MTHFR 677C→T polymorphism and folate status.Conclusions
Individuals with the MTHFR 677 TT genotype
had a significantly higher risk of CHD, particularly in the setting of low
folate status. These results support the hypothesis that impaired folate metabolism,
resulting in high homocysteine levels, is causally related to increased risk
of CHD.
Figures in this Article
Homocysteine is a sulfur-containing amino acid that plays a pivotal
role in methionine metabolism. Genetic defects of the enzymes or dietary deficiency
of B-vitamin cofactors involved in this metabolism result in elevated homocysteine
levels. Elevated homocysteine levels have been associated with increased risk
of coronary heart disease (CHD),1 but whether
this association is causal is uncertain.2 Observational
studies have shown that individuals with low folate levels or intake have
a higher risk of CHD,3- 6 and
it is possible that these associations may be independent of homocysteine.7
A common polymorphism exists for the gene that encodes the methylene
tetrahydrofolate reductase (MTHFR) enzyme, which
converts 5,10-methylene tetrahydrofolate to 5-methyltetrahydrofolate, required
for the conversion of homocysteine to methionine. Individuals who have a C-to-T
substitution at base 677 of the gene (amino acid change A222V) have reduced
enzyme activity and higher homocysteine8 and
lower folate levels than those without this substitution.9- 13 Elucidation
of an association, if any, between this polymorphism and CHD risk might be
informative regarding the hypothesis that impaired folate metabolism, resulting
in high homocysteine concentrations, plays a causal role in the occurrence
of CHD.
Individual studies and previous meta-analyses of such studies8,14 included too few subjects to provide
conclusive evidence for or against an association of this polymorphism and
CHD risk.15 The aim of this study was to assess
the relation of the MTHFR 677C→T polymorphism
with risk of CHD by conducting a meta-analysis of individual participant data
from all case-control observational studies that had data on this polymorphism
and risk of CHD.
Hyperhomocysteinaemia has been identified as a risk factor for cerebrovascular, peripheral vascular and coronary heart disease. Elevated levels of plasma homocysteine can result from genetic or nutrient-related disturbances in the trans-sulphuration or re-methylation pathways for homocysteine metabolism. 5, 10-Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5, 10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, the predominant circulatory form of folate and carbon donor for the re-methylation of homocysteine to methionine. Reduced MTHFR activity with a thermolabile enzyme has been reported in patients with coronary and peripheral artery disease. We have identified a common mutation in MTHFR which alters a highly-conserved amino acid; the substitution occurs at a frequency of approximately 38% of unselected chromosomes. The mutation in the heterozygous or homozygous state correlates with reduced enzyme activity and increased thermolability in lymphocyte extracts; in vitro expression of a mutagenized cDNA containing the mutation confirms its effect on thermolability of MTHFR. Finally, individuals homozygous for the mutation have significantly elevated plasma homocysteine levels. This mutation in MTHFR may represent an important genetic risk factor in vascular disease.
Plasminogen activator inhibitor-1 (PAI-1) plasma levels have been consistently related to a polymorphism (4G/5G) of the PAI-1 gene. The renin-angiotensin pathway plays a role in the regulation of PAI-1 plasma levels. An insertion (I)/deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) gene has been related to plasma and cellular ACE levels. In 1032 employees (446 men and 586 women; 22 to 66 years old) of a hospital in southern Italy, we investigated the association between PAI-1 4G/5G and the ACE I/D gene variants and plasma PAI-1 antigen levels. None of the individuals enrolled had clinical evidence of atherosclerosis. In univariate analysis, PAI-1 levels were significantly higher in men (P<.001), alcohol drinkers (P<.001), smokers (P=.009), and homozygotes for the PAI-1 gene deletion allele (4G/4G) (P=.012). Multivariate analysis documented the independent effect on PAI-1 plasma levels of body mass index (P<.001), triglycerides (P<.001), sex (P<.001), PAI-1 4G/5G polymorphism (P=.019), smoking habit (P=.041), and ACE I/D genotype (P=.042). Thus, in addition to the markers of insulin resistance and smoking habit, gene variants of PAI-1 and ACE account for a significant portion of the between-individual variability of circulating PAI-1 antigen concentrations in a general population without clinical evidence of atherosclerosis.
The enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR) is involved in folate metabolism. The MTHFR gene is located on chromosome 1 (1p36.3), and two common alleles, the C677T (thermolabile) allele and the A1298C allele, have been described. The population frequency of C677T homozygosity ranges from 1% or less among Blacks from Africa and the United States to 20% or more among Italians and US Hispanics. C677T homozygosity in infants is associated with a moderately increased risk for spina bifida (pooled odds ratio = 1.8; 95% confidence interval: 1.4, 2.2). Maternal C677T homozygosity also appears to be a moderate risk factor (pooled odds ratio = 2.0; 95% confidence interval: 1.5, 2.8). The A 1298C allele combined with the C677T allele also could be associated with an increased risk for spina bifida. Some data suggest that the risk for spina bifida associated with C677T homozygosity may depend on nutritional status (e.g., blood folate levels, intake of vitamins) or on the genotype of other folate-related genes (e.g., cystathionine-beta-synthase and methionine synthase reductase). Studies of the C677T allele in relation to oral clefts, Down syndrome, and fetal anticonvulsant syndrome either have yielded conflicting results or have not been yet replicated.
Elevated plasma homocysteine level is an independent risk factor for cardiovascular disease. A common mutation (nucleotid 677C-T) in the gene coding for methylenetetrahydrofolate reductase (MTHFR) has been reported to reduce the enzymatic activity of MTHFR and is associated with elevated plasma levels of homocysteine, especially in subjects with low folate intake.
Methylenetetrahydrofolate reductase T/T genotype may be a risk factor for premature MI in Turkish population who are known to have low folate levels.
The study group was comprised of 96 men (aged <45 years) with premature myocardial infarction (MI) and 100 age- and gender-matched controls who had no history or clinical evidence of coronary artery disease (CAD) and/or MI. DNA was extracted from peripheral blood and genotypes were determined by polymerase chain reaction, restriction mapping with HinfI, and gel electrophoresis. Conventional risk factors for CAD were prospectively documented.
Allele and genotype frequencies among cases and control subjects were compatible with Hardy-Weinberg equilibrium. The frequencies of T/T, C/T, and C/C genotypes among patients with MI and control subjects were 15.6, 40.6, and 43.8%, and 5, 35, and 60%, respectively. Multivariate analyses identified smoking, MTHFR C/T polymorphism, diabetes mellitus, family history of CAD, and hypertension as the independent predictors of premature MI. Defining patients with non-T/T genotype (C/C and C/T combined) as reference, the relative risk of MI for subjects with T/T genotype was 5.94 (95% confidence interval: 1.96-18.02, p = 0.0016).
Our findings suggest that C677T transition in the MTHFR gene may be a risk factor for premature MI in Turkish men.
In observational studies, individuals with elevated levels of plasma homocysteine tend to have moderately increased risk of coronary heart disease (CHD). The MTHFR 677C-->T polymorphism is a genetic alteration in an enzyme involved in folate metabolism that causes elevated homocysteine concentrations, but its relevance to risk of CHD is uncertain.
To assess the relation of MTHFR 677C-->T polymorphism and risk of CHD by conducting a meta-analysis of individual participant data from all case-control observational studies with data on this polymorphism and risk of CHD.
Studies were identified by searches of the electronic literature (MEDLINE and Current Contents) for relevant reports published before June 2001 (using the search terms MTHFR and coronary heart disease), hand searches of reference lists of original studies and review articles (including meta-analyses) on this topic, and contact with investigators in the field.
Studies were included if they had data on the MTHFR 677C-->T genotype and a case-control design (retrospective or nested case-control) and involved CHD as an end point. Data were obtained from 40 (34 published and 6 unpublished) observational studies involving a total of 11 162 cases and 12 758 controls.
Data were collected on MTHFR 677C-->T genotype, case-control status, and plasma levels of homocysteine, folate, and other cardiovascular risk factors. Data were checked for consistency with the published article or with information provided by the investigators and converted into a standard format for incorporation into a central database. Combined odds ratios (ORs) for the association between the MTHFR 677C-->T polymorphism and CHD were assessed by logistic regression.
Individuals with the MTHFR 677 TT genotype had a 16% (OR, 1.16; 95% confidence interval [CI], 1.05-1.28) higher odds of CHD compared with individuals with the CC genotype. There was significant heterogeneity between the results obtained in European populations (OR, 1.14; 95% CI, 1.01-1.28) compared with North American populations (OR, 0.87; 95% CI, 0.73-1.05), which might largely be explained by interaction between the MTHFR 677C-->T polymorphism and folate status.
Individuals with the MTHFR 677 TT genotype had a significantly higher risk of CHD, particularly in the setting of low folate status. These results support the hypothesis that impaired folate metabolism, resulting in high homocysteine levels, is causally related to increased risk of CHD.
Fibrinolysis plays a crucial role in the development of vascular disease. The interface between the plasminogen activators and inhibitors determines the fibrinolytic potential of human blood. In addition to fibrin degradation, fibrinolytic system components modulate several complex biological events such as angiogenesis, tumorigenesis, arteriosclerosis and cellular migration. Recent experimental and clinical data indicated that PAI-1 as a novel vascular risk factor. In this concise review, we will examine the accumulating evidence suggesting that there is an intricate relationship between these systems which may provide new therapeutic strategies for prevention of vascular disease. (C) 2005 Blackwell Publishing Ltd.
Background: Elevated plasma homocysteine level is an independent risk factor for cardiovascular disease. A common mutation (nucleotid 677C-T) in the gene coding for methylenetetrahydrofolate reductase (MTHFR) has been reported to reduce the enzymatic activity of MTHFR and is associated with elevated plasma levels of homocysteine, especially in subjects with low folate intake.Hypothesis: Methylenetetrahydrofolate reductase T/T genotype may be a risk factor for premature MI in Turkish population who are known to have low folate levels.Methods: The study group was comprised of 96 men (aged < 45 years) with premature myocardial infarction (MI) and 100 age- and gender-matched controls who had no history or clinical evidence of coronary artery disease (CAD) and/or MI. DNA was extracted from peripheral blood and genotypes were determined by polymerase chain reaction, restriction mapping with Hinfl, and gel electrophoresis. Conventional risk factors for CAD were prospectively documented.Results: Allele and genotype frequencies among cases and control subjects were compatible with Hardy-Weinberg equilibrium. The frequencies of T/T, C/T, and C/C genotypes among patients with MI and control subjects were 15.6,40.6, and 43.8%, and 5, 35, and 60%, respectively. Multivariate analyses identified smoking, MTHFR C/T polymorphism, diabetes mellitus, family history of CAD, and hypertension as the independent predictors of premature MI. Defining patients with non-T/T genotype (C/C and C/T combined) as reference, the relative risk of MI for subjects with T/T genotype was 5.94 (95% confidence interval: 1.96–18.02, p = 0.0016).Conclusions: Our findings suggest that C677T transition in the MTHFR gene may be a risk factor for premature MI in Turkish men.
Unlabelled:
Over the last decade mild hyperhomocysteinaemia has widely been recognised as a new risk factor for arteriosclerosis and thrombosis. Main regulating enzymes of homocysteine (Hcy) metabolism are cystathionine beta-synthase (CBS), methionine synthase and methylenetetrahydrofolate reductase (MTHFR). Early studies on patients with vascular disease described elevated Hcy concentrations after methionine loading and decreased CBS activity, resembling heterozygotes for CBS deficiency. Therefore, heterozygosity for CBS deficiency was proposed as the main cause of mild hyperhomocysteinaemia. However, more recent enzymatic and molecular genetic studies have demonstrated that heterozygosity for CBS deficiency is not or only a very minor cause of mild hyperhomocysteinaemia in vascular disease. We discovered two common genetic causes of mild hyperhomocysteinaemia, the 677C > T and the 1298A > C mutations in the coding region of MTHFR. The 677C > T mutation causes reduced enzyme activity with thermolabile protein properties, elevated Hcy and low-normal or decreased plasma folate levels. The 1298A > C mutation relates also to decreased enzyme activity, but not to thermolabile protein, and Hcy and folate levels are not influenced. However, compound heterozygosity for these two mutations, i.e. individuals with the 677CT/1298AC genotype, have elevated Hcy and decreased plasma folate levels. Gene-enviroment interactions between 677C > T and folate is demonstrated in individuals with the 677TT genotype. Those with low-normal folate have elevated Hcy, whereas those with high-normal folate have normal Hcy concentrations. The elevated Hcy levels due to these mutations can be normalised by administration of folate, but whether folate reduces the risk of cardiovascular disease remains to be established.
Conclusion:
Heterozygosity for cystathionine beta-synthase deficiency is a minor cause of hyperhomocysteinaemia. The current data on mutations in the methylenetetrahydrofolate reductase gene do not tell us whether elevated plasma homocysteine plays a causal role in vascular disease. Low cellular vitamin status may be a possible cause and homocysteine may just be a marker for this situation.
Plasminogen activator inhibitor-1 (PAI-1), a rapid inhibitor of tissue-type plasminogen activator, has been shown to be an independent risk factor for recurrent myocardial infarction (MI) at a young age. To investigate whether genetic variation in the PAI-1 gene is affecting plasma PAI-1 levels, a sample of 145 patients with an MI before the age of 45 years was genotyped for two polymorphisms at the PAI-1 locus, together with a sample of 95 healthy individuals of a similar age. All individuals were measured for plasma PAI-1 levels as well as for other fibrinolytic and metabolic risk indicators. A HindIII restriction fragment length polymorphism (RFLP) was used in this study in conjunction with a previously unreported eight-allele dinucleotide repeat polymorphism at the PAI-1 locus. The dinucleotide repeat polymorphism and HindIII RFLP were in strong linkage disequilibrium. There was no difference in the frequency of alleles of either polymorphism between patient and control groups. However, the smaller dinucleotide repeat alleles were significantly associated (p = 0.03) with higher plasma PAI-1 levels in the patient sample. This association was also apparent in the control sample but not at significant levels. Differences in regression coefficients for the effect of triglycerides on plasma PAI-1 levels suggest that triglyceride regulation of PAI-1 is genotype specific. Our data suggest that genetic variation at this locus contributes to between-individual differences in the level of plasma PAI-1, which is important in fibrinolysis and the pathogenesis of MI.
Increased plasminogen-activator inhibitor 1 (PAI-1) activity is a common finding in patients with coronary heart disease. Here we provide evidence for an independent, etiological role of PAI-1 in myocardial infarction. The 4G allele of a recently described common 4/5-guanine-tract (4G/5G) polymorphism in the PAI-1 promoter is associated with higher plasma PAI-1 activity. The prevalence of the 4G allele is significantly higher in patients with myocardial infarction before the age of 45 than in population-based controls (allele frequencies of 0.63 vs. 0.53). Both alleles bind a transcriptional activator, whereas the 5G allele also binds a repressor protein to an overlapping binding site. In the absence of bound repressor, the basal level of PAI-1 transcription is increased.
Errors in genotyping data have been shown to have a significant effect on the estimation of recombination fractions in high-resolution genetic maps. Previous estimates of errors in existing databases have been limited to the analysis of relatively few markers and have suggested rates in the range 0.5%-1.5%. The present study capitalizes on the fact that within the Centre d'Etude du Polymorphisme Humain (CEPH) collection of reference families, 21 individuals are members of more than one family, with separate DNA samples provided by CEPH for each appearance of these individuals. By comparing the genotypes of these individuals in each of the families in which they occur, an estimated error rate of 1.4% was calculated for all loci in the version 4.0 CEPH database. Removing those individuals who were clearly identified by CEPH as appearing in more than one family resulted in a 3.0% error rate for the remaining samples, suggesting that some error checking of the identified repeated individuals may occur prior to data submission. An error rate of 3.0% for version 4.0 data was also obtained for four chromosome 5 markers that were retyped through the entire CEPH collection. The effects of these errors on a multipoint map were significant, with a total sex-averaged length of 36.09 cM with the errors, and 19.47 cM with the errors corrected. Several statistical approaches to detect and allow for errors during linkage analysis are presented. One method, which identified families containing possible errors on the basis of the impact on the maximum lod score, showed particular promise, especially when combined with the limited retyping of the identified families. The impact of the demonstrated error rate in an established genotype database on high-resolution mapping is significant, raising the question of the overall value of incorporating such existing data into new genetic maps.
Endothelium-dependent vasodilatation is mediated by release of nitric oxide formed by constitutively expressed endothelial nitric oxide synthase (ecNOS). We explored the distribution of polymorphism ecNOS4a/b in 549 subjects with, and 153 without, coronary artery disease in relation to smoking. In current and ex-cigarette smokers, but not nonsmokers, there was a significant excess of homozygotes for the rare ecNOS4a allele in patients with severely stenosed arteries, compared with those with no or mild stenosis. This genotype was also associated with a history of myocardial infarction. This smoking-dependent excess coronary risk in ecNOS4a homozygotes is consistent with predisposition to endothelial dysfunction.
We have studied PAI-1 activity and antigen content in platelets and in plasma from 37 healthy individuals who were also genotyped for the 4G/5G polymorphism in the PAI-1 promoter region. The PAI-1 data obtained were compared with the vitronectin and the beta-thromboglobulin contents in platelets from the same individuals. A highly significant correlation between PAI-1 activity and PAI-antigen was obtained, both in the plasma samples (p < 0.0001) and in the platelet lysates (p < 0.001). The specific activity of PAI-1 was higher in plasma than in the platelet lysates, but interindividual variation was more pronounced among platelet lysates (range 159,000-1,190,000 U/mg). The calculated specific activity of PAI-1 in platelets seems to be higher than what could be expected from theoretical considerations regarding half-life of platelets in the circulation and conversion of functional PAI-1 to latent PAI-1. On analysis of the influence of the 4G/5G polymorphism, individuals who were homozygous for the 4G allele seemed to have higher levels of PAI-1 activity and antigen in the platelet lysates, when compared to the other genotypes. In platelet lysates, but not in plasma, a strong correlation was observed between the concentrations of PAI-1 and beta-thromboglobulin (r2 = 0.70, p < 0.001). Vitronectin could be detected in the platelet lysates in low concentrations (497 +/- 334 micrograms/l). However, using a newly developed ELISA method for PAI-1-vitronectin complex we failed to demonstrate such a complex in the platelet lysates. Therefore, the mechanism involved in stabilization of PAI-1 activity in the platelets is at present not understood.
In patients with established ischemic heart disease, prospective cohort studies have indicated that plasminogen activator inhibitor (PAI-1), the inhibitor of the fibrinolytic system, may predict cardiovascular events. So far, there have been no primary prospective studies of PAI-1.
The aim of the present study was to test whether plasma levels of PAI-1, tissue-type plasminogen activator (tPA), von Willebrand factor (vWF), and thrombomodulin (TM) could predict the occurrence of a first acute myocardial infarction (AMI) in a population with high prevalence of coronary heart disease by use of a prospective nested case-control design. Mass concentrations of PAI-1 and tPA were significantly higher for the 78 subjects who developed a first AMI compared with the 156 references matched for age, sex, and sampling time; for tPA, this increase was independent of smoking habits, body mass index, hypertension, diabetes, cholesterol, and apolipoprotein A-I. The ratio of quartile 4 to 1 for tPA was 5.9 for a patient to develop a first AMI. The association between tPA and AMI was seen in both men and women. Increased levels of vWF were associated with AMI in a univariate analysis. High levels of TM were associated with AMI in women but not in men.
The plasma levels of PAI-1, tPA, and vWF are associated with subsequent development of a first AMI; for PAI-1 and tPA, this relation was found in both men and women. For tPA but not for PAI-1 and vWF, this association is independent of established risk factors.
Homozygosity for the common (677C-->T) mutation in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with hyperhomocysteinemia, but there is uncertainty as to the association between this mutation and coronary artery disease (CAD). This study examined the association between MTHFR genotypes and age at onset of CAD.
Patients (n=169) with documented myocardial infarction or angiographically documented CAD who were aged < or = 55 years at onset of CAD symptoms and DNA samples from control subjects (n=313) were studied. The prevalence of homozygosity among patients with early CAD onset (aged < or = 45 years) was 28%, which was significantly higher than that in patients with later onset (13%) and in control subjects (14%) (odds ratio 2.4, 95% CI 1.24 to 4.69, P=0.006, and odds ratio 2.7, 95% CI 1.15 to 6.42, P=0.01, respectively). Plasma folate was lower in TT homozygotes who had early CAD onset than in those with later onset (P=0.005). Among patients with plasma folate in the lowest quintile (< or = 12.6 nmol/L), 31% were homozygotes, as were 45% of those with low plasma folate and early CAD onset. There was no difference in the prevalence of traditional risk factors among genotypes. The frequency of homozygosity in patients with < or = 1 risk factor was higher than in those with > or = 2 risk factors (30% versus 12%, P<0.05). In multiple regression analysis, TT homozygosity and plasma folate were independently associated with CAD, but the impact of folate was small.
Homozygosity for the 677C-->T mutation of MTHFR is common and is associated with an increased risk of premature CAD in this population.
We explored the interactive effects of endothelial nitric oxide synthase (eNOS) genotypes and cigarette smoking on protein levels and enzyme activity in 33 postpartum placentas. Whilst the eNOS protein levels were lower in the rare allele (0.48+/-0.11, n=9 vs. 1. 05+/-0.10, n=24, P<0.01), the eNOS enzyme activity was about 7-fold higher in the rare allele (4556.2+/-255.4 vs. 621.8+/-180.5 cpm/mg/min, P<0.01). Smokers had lower eNOS protein levels (1.07+/-0. 09 vs. 0.50+/-0.19, P<0.05) in both alleles. It reduced the eNOS activities only in the rare allele (non-smokers: 6143.8+/-251.2, n=5, smokers: 2968.5+/-259.4, n=4, 52% reduction, P<0.01). We conclude that associations between eNOS polymorphism and protein levels and enzyme activities are modifiable by smoking, the effects of smoking are dependent on the eNOS genotypes.
In this short report, we address some practical problems in performing likelihood-based allelic association analysis of case-control data. Model-free statistics are proposed and their properties assessed by simulation, and procedures based on permutation tests are described for marker-marker as well as marker-disease associations. A memory-efficient algorithm is developed which enables several highly polymorphic markers to be analysed.
A familial component has previously been identified in 11% to 20% of patients with abdominal aortic aneurysms (AAAs). The genetic basis of familial AAA remains elusive, however. Matrix metalloproteinases have been implicated in aneurysm development; and plasmin, a serine protease, activates metalloproteinases. Plasminogen activator inhibitor-1 (PAI-1) regulates plasmin activation through the tissue plasminogen activators. A polymorphism within the promoter area of PAI-1 has been described that modifies PAI-1 expression and consequently plasminogen activation. The 4G homozygous variant is associated with increased PAI-1 expression and consequently reduced plasmin activity and therefore may be selected against in-familial AAA. The purpose of this study was to investigate the incidence of the 4G/5G insertion/deletion polymorphism in the promoter area of the PAI-1 gene in a population with AAA.
Patients seen at a tertiary referral center for repair of abdominal aortic aneurysms were recruited. DNA was extracted from blood. Primers were designed to amplify a 99 (5G)-base pair (bp) and a 98 (4G)-bp fragment bracketing the polymorphism. The 5' primer was mutated to allow a restriction endonuclease to cleave the 5G polymorphism into a 77-bp and a 22-bp fragment. Samples were run on agarose gels and stained with ethidium bromide.
One hundred ninety patients with AAAs, including 39 patients with strong family histories and 163 controls were examined. The frequency of the 4G:5G alleles in the AAA population and in the control population was 0.6:0.4. However, 26% of patients with familial AAA were homozygous 5G compared with 13% of the control population. The 4G-allele frequency was 0.47 in the familial AAAs, compared with 0.62 in the nonfamilial patients (P =.02) and 0.61 in the control population (P =.03).
The selection against the 4G4G genotype in the familial AAA population may indicate a role for PAI in the development of AAA in this population.
The genetic analysis of hypertension has revealed complex and inconsistent results, making it difficult to draw clear conclusions regarding the impact of specific genes on blood pressure regulation in diverse human populations. Some of the confusion from previous studies is probably due to undetected gene-gene interactions. Instead of focusing on the effects of single genes on hypertension, we examined the effects of interactions of alleles at 4 candidate loci. Three of the loci are in the renin-angiotensin-system, angiotensinogen, ACE, and angiotensin II type 1 receptor, and they have been associated with hypertension in at least 1 previous study. The fourth locus studied is a previously undescribed locus, named FJ. In total, 7 polymorphic sites at these loci were analyzed for their association with hypertension in 51 normotensive and 126 hypertensive age-matched individuals. There were no significant differences between the 2 phenotypic classes with respect to either allele or genotype frequencies. However, when we tested for nonallelic associations (linkage disequilibrium), we found that of the 120 multilocus comparisons, 16 deviated significantly from random in the hypertensive class, but there were no significant deviations in the normotensive group. These findings suggest that genetic interactions between multiple loci rather than variants of a single gene underlie the genetic basis of hypertension in our study subjects. We hypothesize that such interactions may account for the inconsistent findings in previous studies because, unlike our study, prior studies almost always examined single-locus effects and did not consider the effects of variation at other potentially interacting loci.
High plasminogen activator inhibitor-1 (PAI-1) plasma levels increase future risk of myocardial infarction (MI). The 4G allele of the 4G/5G polymorphism of the PAI-1 gene has been associated with increased plasma levels of PAI-1. The association of the PAI-1 polymorphism with coronary narrowings, coronary thrombosis and myocardial infarction (MI) was studied in a prospective autopsy series of 300 middle-aged Caucasian Finnish men (33 to 69 yrs) suffering sudden out-of-hospital death (Helsinki Sudden Death Study). The 4G allele was found in 76.8% of men with sudden cardiac death (SCD) compared to 67.5% in men who died accidentally and 63.2% in men who died of other diseases (p = 0.08 and p = 0.055, respectively). Men possessing the 4G allele had more often acute MI (OR 3.5; p <0.05) and coronary thrombosis (OR 5.5. p = 0.01) compared to 5G homozygotes. 5G homozygotes, comprising one third of the men in our study, seem to be at a decreased risk of thrombosis, whereas carriers of the common 4G allele have an increased risk of thrombosis, AMI and possibly SCD compared to 5G homozygotes.
One of the greatest challenges facing human geneticists is the identification and characterization of susceptibility genes for common complex multifactorial human diseases. This challenge is partly due to the limitations of parametric-statistical methods for detection of gene effects that are dependent solely or partially on interactions with other genes and with environmental exposures. We introduce multifactor-dimensionality reduction (MDR) as a method for reducing the dimensionality of multilocus information, to improve the identification of polymorphism combinations associated with disease risk. The MDR method is nonparametric (i.e., no hypothesis about the value of a statistical parameter is made), is model-free (i.e., it assumes no particular inheritance model), and is directly applicable to case-control and discordant-sib-pair studies. Using simulated case-control data, we demonstrate that MDR has reasonable power to identify interactions among two or more loci in relatively small samples. When it was applied to a sporadic breast cancer case-control data set, in the absence of any statistically significant independent main effects, MDR identified a statistically significant high-order interaction among four polymorphisms from three different estrogen-metabolism genes. To our knowledge, this is the first report of a four-locus interaction associated with a common complex multifactorial disease.
To study genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) C677T and cystathionine beta-synthase(CBS) T833C related to homocysteine metabolism in patients with coronary heart disease (CHD).
209 patients with CHD and 101 controls were selected. MTHFR genetic C677T polymorphism was determined by PCR-RFLP, and CBS T833C polymorphism by ARMS method. Plasma homocysteine levels were detected with HPLC.
The frequencies of MTHFR T homogenetic type and heterogenetic type (27.8% and 45.4%) in case group were higher than those in normal group(22.8% and 34.6%). There were significant differences in the frequencies of genotypes and alleles between two groups (P < 0.05). C homogenotype of CBS gene was found in 21 patients, and 2 in the normal group. There were evident differences in the frequencies of genotypes and alleles of the two groups (P < 0.001). Moreover, plama homocysteine levels were markedly higher in patients with MTHFR or CBS genetic mutation than those in patients without mutation (P < 0.05).
Hyperhomocysteinemia is an independent risk factor of CHD. MTHFR and CBS are the main enzymes related to homocysteine metabolism. Their genetic mutations are possibly important mechanism of hyperhomocysteinemia and coronary heart disease.
The endothelium plays a key role in vascular homeostasis through the release of a variety of autocrine and paracrine substances, the best characterized being nitric oxide. A healthy endothelium acts to prevent atherosclerosis development and its complications through a complex and favorable effect on vasomotion, platelet and leukocyte adhesion and plaque stabilization. The assessment of endothelial function in humans has generally involved the description of vasomotor responses, but more widely includes physiological, biochemical and genetic markers that characterize the interaction of the endothelium with platelets, leukocytes and the coagulation system. Stable markers of inflammation such as high sensitivity C-reactive protein are indirect and potentially useful measures of endothelial function for example.
Attenuation of the effect of nitric oxide accounts for the majority of what is described as endothelial dysfunction. This occurs in response to atherosclerosis or its risk factors. Much remains to be learned about the molecular and genetic pathophysiological mechanisms of endothelial cell abnormalities. However, pharmacological intervention with a growing list of medications can favorably modify endothelial function, paralleling beneficial effects on cardiovascular morbidity and mortality. In addition, several small studies have provided tantalizing evidence that measures of endothelial health might provide prognostic information about an individual patient’s risk of subsequent events. As such, the sum of this evidence makes the clinical assessment of endothelial function an attractive surrogate marker of atherosclerosis disease activity. The review will focus on the role of nitric oxide in atherosclerosis and the clinical relevance of these findings.
Hyperhomocysteinemia has been associated with increased risk of atherosclerosis and myocardial infarction by a number of prospective case-control studies. A variety of genetic mutations, nutritional deficiencies, disease states, and drugs can elevate homocysteine concentrations. Treatment with folic acid with or without B-complex vitamins effectively lowers homocysteine levels. Whether therapy corresponds with decreased risk of coronary events is unknown, but may be promising. This article reviews the biochemistry of homocysteine metabolism, pathogeneisis, and etiology of hyperhomocysteinemia, along with its association with coronary artery disease, screening, and treatment.
While hypertension is a complex disease with a well-documented genetic component, genetic studies often fail to replicate findings. One possibility for such inconsistency is that the underlying genetics of hypertension is not based on single genes of major effect, but on interactions among genes. To test this hypothesis, we studied both single locus and multilocus effects, using a case-control design of subjects from Ghana. Thirteen polymorphisms in eight candidate genes were studied. Each candidate gene has been shown to play a physiological role in blood pressure regulation and affects one of four pathways that modulate blood pressure: vasoconstriction (angiotensinogen, angiotensin converting enzyme - ACE, angiotensin II receptor), nitric oxide (NO) dependent and NO independent vasodilation pathways and sodium balance (G protein-coupled receptor kinase, GRK4). We evaluated single site allelic and genotypic associations, multilocus genotype equilibrium and multilocus genotype associations, using multifactor dimensionality reduction (MDR). For MDR, we performed systematic reanalysis of the data to address the role of various physiological pathways. We found no significant single site associations, but the hypertensive class deviated significantly from genotype equilibrium in more than 25% of all multilocus comparisons (2,162 of 8,178), whereas the normotensive class rarely did (11 of 8,178). The MDR analysis identified a two-locus model including ACE and GRK4 that successfully predicted blood pressure phenotype 70.5% of the time. Thus, our data indicate epistatic interactions play a major role in hypertension susceptibility. Our data also support a model where multiple pathways need to be affected in order to predispose to hypertension.
Ethnic differences in the prevalence of complex diseases such as atherosclerosis are undoubtedly multifactorial. It is clear that there are social, environmental, biologic, genetic, and other determinants leading to disparities in the rate of coronary heart disease among different ethnic and racial groups. Many epidemiologic studies have characterized the social and environmental factors leading to these differences, but there has been relatively limited investigation of the potential biologic and genetic factors involved. In this review, we will summarize currently available data on ethnic differences in cardiac risk factors, vascular biology, and genetic determinants of atherosclerosis.
Single point mutations in the genes coding for factor V [G1691A; Leiden], prothrombin [PRT; G20210A], and methylenetetrahydrofolate reductase [MTHFR, C677T] were shown to be major inherited predisposing factors for venous thromboembolism. However, their contribution in the development of coronary artery disease [CAD] remains controversial. The aim of the study was to examine the association of these mutations in CAD.
A total of 96 patients with angiographically-demonstrated CAD [mean age 55.3 +/- 11.3], and 404 healthy subjects [mean age 50.7 +/- 8.9] were recruited into the study. Fasting plasma homocysteine was determined by HPLC, and genotype analysis was assessed by PCR-RFLP.
The carrier frequency of factor V-Leiden (14.6% vs. 15.1%, p = 0.617) and PRT G20210A (3.1% vs. 3.0%; p = 0.936) were similar between patients and controls, respectively. In contrast, the frequency of the MTHFR variant C677T was 71.9% among patients compared with 45.5% in controls (p < 0.001), of which the T/T genotype was significantly higher among patients (31.3%) than controls (4.5%; p < 0.001). Significantly higher homocysteine levels were seen among T/T genotype in both groups compared to non-T/T carriers (p < 0.05), and among patients compared with controls (18.47 +/- 3.73 micromol/L vs. 16.28 +/- 4.16 micromol/L). In addition, the coexistence of MTHFR C677T with FV-Leiden was seen in 10.4% of CAD patients compared 6.9% of controls (p = 0.001).
While results from this study clearly demonstrate a strong association of hyperhomocysteinemia and homozygosity of the MTHFR C677T, but not FV-Leiden or PRT G20210A, mutations with confirmed CAD, they also suggest a potential role for factor V-Leiden in MTHFR C677T carriers.
Knowledge of genetic factors in the etiology of coronary heart disease has not so far been adequately utilized in attempts to combat premature CHD. The time has now come to utilize genetic information in a setting of family-oriented preventive medicine. This approach would greatly improve the efficiency of preventive efforts, utilizing predictive genetic testing and targeting counseling on those who need it most. 1
The optimistic predictions of the impact of genetics on the diagnosis and prevention of coronary heart disease (CHD) have not been realized, and whether DNA testing will be incorporated into clinical cardiology practice in the next decades is unclear. Most of the genetic variations identified thus far either are rare or influence traditional risk factors such as low HDL, elevated LDL, high blood pressure, and diabetes. Several recent advances, however, make a case for renewed optimism (see Part I of this review). Studies in humans and mice have begun to reveal highly penetrant genetic factors that contribute to CHD susceptibility independent of traditional risk factors. As technical advances bring down genotyping costs, we may pass a threshold for the cost–benefit ratio in the near future. One important application in diagnosis is likely to involve the identification of different forms of CHD to allow individualized treatment (pharmacogenetics). The application of multilocus genotyping to assess risk or to screen populations for individuals who are highly susceptible to CHD also is a possibility. Perhaps most important, genetic studies are leading to many insights into disease mechanisms, and these studies, along with biochemical approaches, are pointing to new therapeutic concepts and treatments.
Probably the most significant impact of genetic studies on medicine pertains to the development of therapies. The outstanding example is the impetus that genetic studies of familial hypercholesterolemia (FH) provided in the development of hepatic hydroxymethyl glutaryl coenzyme …
There is a complex pathophysiologic scenario involving nitric oxide (NO), endothelial nitric oxide synthase (eNOS), and the development of atherosclerosis and unstable atheroma. Endothelial damage induced by atherosclerosis leads to the reduction in bioactivity of eNOS with subsequent impaired release of NO. An important mechanism is local enhanced degradation of NO by increased generation of reactive oxygen species and other free radicals, with subsequent cascade of oxidation-sensitive mechanisms in the arterial wall. Novel molecular approaches have resulted in the development of new strains of mice lacking eNOS. These experimental models will help to understand how to implement NO-based therapies against atherosclerosis. L-arginine, the precursor of NO, has demonstrated beneficial effects in atherosclerosis and disturbed shear stress. The target or goal for new drugs should be the complete restoration of NO-mediated signaling pathways in atherosclerotic arteries.
Fibrinolysis plays a crucial role in the development of vascular disease. The interface between the plasminogen activators and inhibitors determines the fibrinolytic potential of human blood. In addition to fibrin degradation, fibrinolytic system components modulate several complex biological events such as angiogenesis, tumorigenesis, arteriosclerosis and cellular migration. Recent experimental and clinical data indicated that PAI-1 as a novel vascular risk factor. In this concise review, we will examine the accumulating evidence suggesting that there is an intricate relationship between these systems which may provide new therapeutic strategies for prevention of vascular disease.
Cardiovascular disease is a leading cause of mortality in the United States, and is a significant cause of death worldwide. In 2002, it accounted for 38.0% of all deaths in the US, and approximately one-third of all global deaths. It has a significant economic impact, with an estimated cost in the US of 393.5 billion US dollars for 2005. The most common form of heart disease is coronary heart disease (CHD)(1)/coronary artery disease (CAD) resulting from atherosclerosis. Thirteen million Americans are affected by CHD annually, with 7.1 million of these experiencing a myocardial infarction (MI). Five to ten percent of new MI's occur in individuals younger than age 50, and the lifetime risk of developing CAD after age 40 ranges from 32% in women to 49% in men. Because of its major impact on morbidity and mortality, as well as its contribution to annual health care costs, it is of the utmost importance that improved strategies for preventing and treating CAD be developed. A promising, but inherently difficult, area of study is the identification of genes that predispose to or directly cause CAD. The identification of these genes may lead to screening tests that will allow persons at risk for developing CAD to be identified early enough that prevention/intervention strategies can be implemented to prevent or ameliorate the disease process, and may also lead to the development of gene therapy mechanisms useful in the treatment of ischemic heart disease (IHD). Because an exhaustive review of all the genes being studied in relation to CAD and MI is difficult within the confines of a review article, this review will focus on describing representative studies investigating the genes considered most likely to potentially contribute toward an increased risk for CAD and MI. Genes resulting in inherited disorders with which an increased risk of CAD and MI is associated will be discussed, as well as a number of candidate genes that may play a role in the multifactorial inheritance of CHD risk.