Lack of association of methylenetetrahydrofolate reductase 677C>T mutation with coronary artery disease in a Pakistani population

MTHFR gene polymorphisms and susceptibility to myocardial infarction: Evidence from meta-analysis and trial sequential analysis

Background

This meta-analysis aimed to provide a comprehensive assessment of the association between Methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms, specifically C677T and A1298C, and the susceptibility to myocardial infarction (MI).

Methods

A systematic literature search was conducted in MEDLINE, Web of Science, and Scopus until April 2023 to identify studies investigating the relationship between MTHFR gene polymorphisms (C677T and A1298C) and the risk of MI.

Results

The analysis included 66 studies involving 16,860 cases and 20,403 controls for the C677T polymorphism and 18 studies comprising 3162 cases and 3632 controls for the A1298C polymorphism. Significant associations were observed between the C677T polymorphism and MI risk in various genetic models: dominant (OR = 1.16, 95 % CI = 1.06-1.28, P = 0.008), recessive (OR = 1.20, 95 % CI = 1.12-1.28, P < 0.001), allelic (OR = 1.13, 95 % CI = 1.06-1.21, P < 0.001), TT vs. CC (OR = 1.19, 95 % CI = 1.05-1.36, P < 0.001), and CT vs. CC (OR = 1.11, 95 % CI = 1.02-1.21, P = 0.01). Furthermore, an overall analysis indicated a marginally significant association between the A1298C polymorphism and MI risk in the recessive model (OR = 1.27, 95 % CI = 1.06-1.51, P = 0.008), allelic model (OR = 1.18, 95 % CI = 1.01-1.39, P = 0.03), and CC vs. AA model (OR = 1.22, 95 % CI = 1.01-1.47, P = 0.04). Meta-regression analysis revealed that none of the potential factors contributed to the observed heterogeneity.

Conclusions

This meta-analysis revealed an association between MTHFR gene C677T and A1298C polymorphisms and the risk of MI.

C667T and A1298C polymorphisms of methylenetetrahydrofolate reductase gene and susceptibility to myocardial infarction: A systematic review and meta-analysis

MTHFR C677T and A1298C polymorphisms have been reported to be associated with the risk of myocardial infarction (MI), although the results of previous studies have been inconsistent. The aim of this study was to explore whether these polymorphisms play a role in the genetic susceptibility to MI. A comprehensive search of MEDLINE and EMBASE databases was conducted for studies evaluating the association between the C667T and A1298C polymorphisms and MI risk. Odds ratios (OR) with 95% confidence intervals (CIs) were calculated to assess the strength of association in the dominant model, recessive model, allelic model, and genotypes contrast. A total of 47 studies were finally included in this meta-analysis. Overall, the results showed no statistically significant association between C667T and A1298C polymorphisms and MI risk. However, in subgroup analysis by ethnicity, the T allele of C677T polymorphism was associated with a 63% increased risk of MI compared with the C allele (T vs. C, OR=1. 63, 95%CI=1.15-2.10, fixed effects) in African populations, while compared to wild homozygote genotype, CT genotype was associated with a decreased risk of MI in North American populations (CT vs. CC, OR=0.81, 95%CI=0.64-0.98, fixed effects). Moreover, C677T polymorphism had a protective effect against MI risk under the dominant model (OR=0.93, 945%CI=0.87-0.99, fixed effects) in elderly (≥50) population. The A1298C polymorphism was not significantly associated with MI risk. Unlike A1298C polymorphism, C677T polymorphism was associated with risk of MI in African, North American, and elderly populations.

Association of C677T MTHFR and G20210A FII prothrombin polymorphisms with susceptibility to myocardial infarction

Myocardial infarction (MI) is a common complex pathology, localized in the main leading causes of mortality worldwide. It is the result of the interaction of genetic and environmental factors. The aim of the present study was to investigate the potential association of C677T 5,10-methylenetetrahydrofolate reductase (MTHFR) (rs1801133) and G20210A factor II prothrombin (FII) (rs1799963) polymorphisms with the susceptibility of MI. Following extraction by the standard salting-out procedure, DNA samples of 100 MI patients and 182 apparently healthy controls were genotyped by polymerase chain reaction-restriction fragment length polymorphism using HinfI and HindIII restriction enzymes, respectively. The results show a significant association of the G20210T FII polymorphism with the MI risk. The frequencies of the heterozygote genotype GA, homozygous mutated AA and the G20210A allele was higher among patients compared to controls (GA: 59 vs. 5.5%, P<0.001; AA: 10 vs. 0%, P=0.003; and 20210A: 39.5 vs. 2.7%, P<0.003), suggesting that this polymorphism may be a potential genetic marker for MI. No significant association was observed between the C677T MTHFR and MI occurrence, and there was more heterozygote CT in the patient group compared to the controls. As a multifactorial disease, the development of MI may be the result of numerous factors that influence synergistically its occurrence. Thus, further studies are merited to try to better assess these associations (gene-gene and gene-environment interactions).

Detailed analysis of gene polymorphisms associated with ischemic stroke in South Asians

The burden of stroke is disproportionately high in the South Asian subcontinent with South Asian ethnicity conferring a greater risk of ischemic stroke than European ancestry regardless of country inhabited. While genes associated with stroke in European populations have been investigated, they remain largely unknown in South Asians. We conducted a comprehensive meta-analysis of known genetic polymorphisms associated with South Asian ischemic stroke, and compared effect size of the MTHFR C677T-stroke association with effect sizes predicted from homocysteine-stroke association. Electronic databases were searched up to August 2012 for published case control studies investigating genetic polymorphisms associated with ischemic stroke in South Asians. Pooled odds ratios (OR) for each gene-disease association were calculated using a random-effects model. We identified 26 studies (approximately 2529 stroke cases and 2881 controls) interrogating 33 independent genetic polymorphisms in 22 genes. Ten studies described MTHFR C677T (108 with TT genotype and 2018 with CC genotype) -homocysteine relationship and six studies (735 stroke cases and 713 controls) described homocysteine-ischemic stroke relationship. Risk association ORs were calculated for ACE I/D (OR 5.00; 95% CI, 1.17–21.37; p = 0.03), PDE4D SNP 83 (OR 2.20; 95% CI 1.21–3.99; p = 0.01), PDE4D SNP 32 (OR 1.57; 95% CI 1.01–2.45, p = 0.045) and IL10 G1082A (OR 1.44; 95% CI, 1.09–1.91, p = 0.01). Significant association was observed between elevated plasma homocysteine levels and MTHFR/677 TT genotypes in healthy South Asians (Mean difference (ΔX) 5.18 µmol/L; 95% CI 2.03–8.34: p = 0.001). Our results demonstrate that the genetic etiology of ischemic stroke in South Asians is broadly similar to the risk conferred in Europeans, although the dataset is considerably smaller and warrants the same clinical considerations for risk profiling.

Genetic polymorphisms and the risk of myocardial infarction in patients under 45 years of age

This study investigates the potential role of 17 chosen polymorphisms in 15 candidate genes and the risk of myocardial infarction in patients under 45 years of age. The study consists of 271 patients with myocardial infarction and 141 controls. The analysis of genetic polymorphisms was performed using the PCR–RFLP method. Of the chosen polymorphisms, two (Leu125Val PECAM1 and A1/A2 FVII) are related to myocardial infarction and two (C677T MTHFR and 5A/6A MMP3) to advanced stenosis in arterial vessels (> 75%). We also found that the frequency of some combinations among the analyzed genes and environmental factors varied between the patient and control groups.

Polymorphisms in MTHFR, MS and CBS genes and homocysteine levels in a Pakistani population

BACKGROUND

Hyperhomocysteinemia (>15 µmol/L) is highly prevalent in South Asian populations including Pakistan. In order to investigate the genetic determinants of this condition, we studied 6 polymorphisms in genes of 3 enzymes--methylenetetrahydrofolate reductase (MTHFR; C677T; A1298C), methionine synthase (MS; A2756G), cystathionine-β-synthase (CBS; T833C/844ins68, G919A) involved in homocysteine metabolism and investigated their interactions with nutritional and environmental factors in a Pakistani population.

METHODOLOGY/PRINCIPAL FINDINGS

In a cross-sectional survey, 872 healthy adults (355 males and 517 females; age 18-60 years) were recruited from a low-income urban population in Karachi. Fasting venous blood was obtained and assessed for plasma/serum homocysteine; folate, vitamin B12, pyridoxal phosphate and blood lead. DNA was isolated and genotyping was performed by PCR-RFLP (restriction-fragment-length-polymorphism) based assays. The average changes in homocysteine levels for MTHFR 677CT and TT genotypes were positive [β(SE β), 2.01(0.63) and 16.19(1.8) µmol/L, respectively]. Contrary to MTHFR C677T polymorphism, the average changes in plasma homocysteine levels for MS 2756AG and GG variants were negative [β(SE β), -0.56(0.58) and -0.83(0.99) µmol/L, respectively]. The average change occurring for CBS 844ins68 heterozygous genotype (ancestral/insertion) was -1.88(0.81) µmol/L. The combined effect of MTHFR C677T, MS A2756G and CBS 844ins68 genotypes for plasma homocysteine levels was additive (p value <0.001). Odds of having hyperhomocysteinemia with MTHFR 677TT genotype was 10-fold compared to MTHFR 677CC genotype [OR (95%CI); 10.17(3.6-28.67)]. Protective effect towards hyperhomocysteinemia was observed with heterozygous (ancestral/insertion) genotype of CBS 844ins68 compared to homozygous ancestral type [OR (95% CI); 0.58 (0.34-0.99)]. Individuals with MTHFR 677CT or TT genotypes were at a greater risk of hyperhomocysteinemia in folate and vitamin B12 deficiencies and high blood lead (p value <0.05) level.

CONCLUSIONS

Gene polymorphism (especially MTHFR C677T transition), folate and vitamin B12 deficiencies, male gender and high blood lead level appear to be contributing towards the development of hyperhomocysteinemia in a Pakistani population.

Association between polymorphism of methylenetetrahydrofolate reductase (MTHFR) C677T and risk of myocardial infarction: a meta-analysis for 8,140 cases and 10,522 controls

BACKGROUND AND AIMS

The methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism has been reported to be associated with myocardial infarction (MI), but results from previous studies are conflicting. The present study aimed at investigating the association between this polymorphism and risk of MI using a meta-analysis on the published studies.

METHODS

Medline, EBSCO, BIOSIS, and Cochrane Library were searched to identify eligible studies published in English before August, 2011. Data were extracted using standardized methods. The association was assessed by odds ratio (OR) with 95% confidence intervals (CI). Begg's test was used to measure publication bias.

RESULTS

A total of 30 case-control studies containing 8,140 MI cases and 10,522 controls were involved in this meta-analysis. Overall, significant association was found between MTHFR C677T polymorphism and risk of MI when all studies pooled with fixed-effects model for TT vs. CT (OR = 1.183, 95% CI: 1.076-1.300). In the subgroup analysis, the same association was found in overall Caucasians (OR = 1.139, 95% CI: 1.007-1.288) and young/middle-aged (<50 years) Caucasians (OR = 1.275, 95% CI: 1.077-1.509). No associations were detected between MTHFR C677T and the risk of MI in elderly male or female Caucasians, East Asians, South Asians, and African-Americans.

CONCLUSIONS

Meta-analysis results suggest that the MTHFR C677T polymorphism was associated with risk of MI in young/middle-aged Caucasians. The effect of the variants on the expression levels and the possible functional role of the variants in MI should be addressed in further studies.

Polymorphisms of methylenetetrahydrofolate reductase gene as the genetic predispositions of coronary artery diseases in eastern India

Background:

Gene–environment interaction is an important aspect in the development of coronary artery disease (CAD). The mutation (677C-T) of methylenetetrahydrofolate reductase (MTHFR) gene results in a decrease of the enzyme activity that leads to mild hyperhomocysteinemia. Elevated plasma level of homocysteine has been recognized as an independent risk factor for cardiovascular disease. A case–control study was designed to assess whether the prevalence of some MTHFR gene polymorphisms have any role in the development of CAD.

Materials and Methods:

The study included unrelated 217 cases with CAD and 255 healthy controls. DNA was extracted from peripheral blood. MTHFR genotypes were identified by seeing the presence or absence of 677C→T mutation obtained by PCR followed by Hinf1 restriction digestion. Multiple logistic regression analysis was carried out to find association between studied genotypes and lifestyle as well as biochemical risk factors.

Results:

The T allele was found to be associated with the disease. Significant associations were found with smoking, hypertension, diabetes, and family history of CAD.

Conclusion:

The results indicate that MTHFR 677C-T polymorphism has significant association with CADs in the population of eastern India.

C677T polymorphism of the 5,10 MTHFR gene in young Mexican subjects with ST-elevation myocardial infarction

BACKGROUND AND AIMS

The C677T polymorphism of 5,10 methylenetetrahydrofolate reductase (MTHFR) gene has been associated with hypertension and coronary artery disease in several populations worldwide, but results are still controversial. The aim of this study was to examine the possible association of C677T polymorphism with ST-elevation myocardial infarction (STEMI) in young Mexican subjects.

METHODS

In a case-control study, 167 unrelated patients < or = 45 years of age with diagnosis of STEMI who were admitted to a cardiovascular intense care unit and 167 unrelated controls subjects matched by age and gender were recruited from January 2006 and June 2009. The C677T polymorphism was determined in all participants by a polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP).

RESULTS

There was no significant difference in the genotype distribution between groups (p = 0.69) or allele frequency (p = 0.40). There were independent factors for STEMI: smoking (OR 4.9, 95% CI 3.0-8.1, p = 0.001), hypertension (OR 1.8, 95% CI 1.0-3.3, p = 0.03), family history of atherothrombotic disease (OR 2.3, 95% CI 2.0-4.6, p = 0.02), and dyslipidemia (OR 3.2, 95% CI 1.8-5.6, p <0.001). Diabetes mellitus did not represent an independent risk factor for STEMI (OR 1.2, 95% CI 0.2-2.2, p = 0.82).

CONCLUSIONS

The TT genotype from the C677T of 5,10 MTHFR gene is not an independent risk factor for STEMI in the Mexican population. However, more studies are needed to determine the possible "protective effect" of the C677T polymorphism in our population.