Prevalence of methylenetetrahydrofolate gene (MTHFR) C677T polymorphism among chronic hemodialysis patients and its association with cardiovascular disease: a cross-sectional analysis

Decisive evidence corroborates a null relationship between MTHFR C677T and chronic kidney disease: A case-control study and a meta-analysis

BACKGROUND

Previous meta-analyses have explored the association between the C677T polymorphism of methyltetrahydrofolate reductase (MTHFR) and chronic kidney disease (CKD) but there were no studies with a decisive conclusion. Furthermore, the high heterogeneity among different populations is not yet interpreted.

OBJECTIVES

This study used trial sequential analysis (TSA) to evaluate whether the nowadays conclusion supported by current cumulative samples. We also applied case-weighted meta-regression to explore the potential gene-environment interactions.

METHODS

For the first stage of this study we conducted a case-control study involving 847 dialysis patients from 7 hemodialysis centers in Taipei during 2015 to 2018 and 755 normal controls from a health center in the Tri-Service General Hospital. The second stage combined the results from the first stage with previous studies. The previous studies were collected from PubMed, EMBASE, and Web of Science databases before January 2018.

RESULTS

From the case-control study, the T allele of MTHFR C677T appeared to have a protective effect on end-stage renal disease compared with the C allele [odds ratio (OR): 0.80, 95% CI (confidence interval) = 0.69-0.93]. However, the meta-analysis contradicted the results in Asian (OR = 1.12, 95% CI = 0.96-1.30). The same analysis was also applied in Caucasian and presented similar results from Asian (OR = 1.18, 95% CI = 0.98-1.42). The TSA showed our case-control study to be the decisive sample leading to a null association among Asian population. The high heterogeneity (I = 75%) could explain the contradictory results between the case-control study and the meta-analysis. However, further case-weighted meta-regression did not find any significant interaction between measured factors and MTHFR C677T on CKD.

CONCLUSIONS

High heterogeneities were found in both Caucasian and Asian, which caused the null relationship in meta-analysis while there were significant effects in individual studies. Future studies should further explore the high heterogeneity that might be hidden in unmeasured gene-environment interactions, to explain the diverse findings among different populations.

Correlations of MTHFR 677C>T polymorphism with cardiovascular disease in patients with end-stage renal disease: a meta-analysis

OBJECTIVE

This meta-analysis was conducted to evaluate the correlations of a common polymorphism (677C>T) in the methylenetetrahydrofolate reductase (MTHFR) gene with risk of cardiovascular disease (CVD) in patients with end-stage renal disease (ESRD).

METHOD

The following electronic databases were searched without language restrictions: Web of Science (1945∼2013), the Cochrane Library Database (Issue 12, 2013), MEDLINE (1966∼2013), EMBASE (1980∼2013), CINAHL (1982∼2013) and the Chinese Biomedical Database (CBM) (1982∼2013). Meta-analysis was performed using STATA statistical software. Odds ratios (ORs) with their 95% confidence intervals (95%CIs) were calculated.

RESULTS

Eight cohort studies met all inclusion criteria and were included in this meta-analysis. A total of 2,292 ESRD patients with CVD were involved in this meta-analysis. Our meta-analysis results revealed that the MTHFR 677C>T polymorphism might increase the risk of CVD in ESRD patients (TT vs. CC: OR = 2.75, 95%CI = 1.35∼5.59, P = 0.005; CT+TT vs. CC: OR = 1.39, 95%CI = 1.09∼1.78, P = 0.008; TT vs. CC+CT: OR = 2.52, 95%CI = 1.25∼5.09, P = 0.010; respectively). Further subgroup analysis by ethnicity suggested that the MTHFR 677C>T polymorphism was associated with an elevated risk for CVD in ESRD patients among Asians (TT vs. CC: OR = 3.38, 95%CI = 1.11∼10.28, P = 0.032; CT+TT vs. CC: OR = 1.44, 95%CI = 1.05∼1.97, P = 0.022; TT vs. CC+CT: OR = 3.15, 95%CI = 1.02∼9.72, P = 0.046; respectively), but not among Africans or Caucasians (all P>0.05).

CONCLUSION

Our findings indicate that the MTHFR 677C>T polymorphism may be associated with an elevated risk for CVD in ESRD patients, especially among Asians.

Inherited thrombophilia and recurrent pregnancy loss

Background:

Recurrent pregnancy loss (RPL) is a common health problem. The polymorphisms G20210A of prothrombin gene (FII G 20210A), and G 1691A of factor V gene (Factor V Leiden, FVL) are the most extensively studied thrombophilic mutations in association to recurrent miscarriage.

Objectives:

To determine the frequency of FII G20210A and FVL polymorphisms as well as protein C and protein S deficiency in a series of patients with RPL compared with control group.

Patients and Methods:

The study group included 90 randomly selected patients with three or more consecutive miscarriages with the same partner in <20 weeks gestation in 2012. The control population consisted of 44 age-matched women with at least one live born children and no history of pregnancy loss. Functional activity of protein C and S, activated protein C resistance, FVL assay by polymerase chain reaction and prothrombin gene mutation were assessed. The polymorphism frequencies were recorded for each group and comparisons were made.

Results:

The mean functional activity of protein C and protein S were not significantly different between case and control groups (P >0.05). Frequency of protein C deficiency was also not significantly different between the case and control groups (P=0.906), but frequency of protein S deficiency was significantly higher in patients than controls (P=0.03). Genotype pattern of the patients and healthy individuals were not significantly different with regard to either FVL or Prothrombin G20210A (P > 0.05).

Conclusions:

We determined a significant higher frequency of protein S deficiency in patients with RPL compared with controls. But the frequency of protein C deficiency and the frequency of two common thrombophilic mutations (Factor V Leiden and Prothrombin G20210A), were not significantly different between patients with recurrent miscarriage and healthy women.

Higher incidence of C677T polymorphism of the MTHFR gene in North Indian patients with vascular disease

Homocysteine is a sulfur-containing amino acid, which is derived from dietary methionine. Hyperhomocysteinemia has been implicated in vascular disease for over a decade now, and can be treated with B vitamins. Among its causes is polymorphism of the MTHFR gene, the most common being the cytidine to thymidine at position 677 (MTHFR C677T), which gives rise to three genotypes - normal homozygous CC, heterozygous CT and homozygous variant TT. An attempt was made to ascertain the prevalence of this MTHFR C677T in our population so that preventive measures may accordingly be instituted. Blood samples from 70 patients with vascular disease and 70 healthy controls were analyzed for plasma homocysteine levels (chemiluminescent immunoassay) and for the presence of MTHFR C677T (polymerase chain reaction analysis). Homocysteine was higher in the homozygous subjects (TT genotype) than in the heterozygous (CT genotype). In patients, the frequency of the C allele was significantly lower, and that of the T allele was significantly higher than the corresponding frequencies in controls. In conclusion, the North Indian urban population has higher homocysteine levels associated with the TT genotype. Hence, instituting measures towards reduction of homocysteine levels in the population would probably reduce the incidence and morbidity of vascular disease in our population.

MTHFR C677T polymorphism and its relationship to myocardial infarction in the Eastern Black Sea region of Turkey

BACKGROUND AND AIMS

An association of homozygous MTHFR 677T genotypes with elevated plasma homocysteine level has been documented, but results are still controversial. We aimed to investigate prevalence of the C677T polymorphism in patients with acute myocardial infarction (MI) in the Eastern Black Sea region of Turkey.

METHODS

We studied genomic DNA of 231 unrelated patients (aged 59 ± 13 years; 175 male, 56 female) with first anterior acute MI and 242 healthy controls (aged 54 ± 19 years; 182 male, 60 female) using real-time polymerase chain reaction kits for the MTHFR C677T mutation.

RESULTS

Prevalence of MTHFR C677T mutant genotype was 49.1% (CT: 45.8%, TT: 3.3%) in controls and 48.45% (CT: 38.5%, TT: 9.95%) in patients with acute MI. The TT mutation was more frequent in patients with acute MI than in controls (9.95 vs. 3.3%) (OR; 3.23, 95% CI; [1.34-8.05], p = 0.003).

CONCLUSIONS

The MTHFR gene homozygote TT mutation is a risk factor for patients with MI in the eastern Black Sea Turkish Population.

Methylenetetrahydrofolate reductase (MTHFR) polymorphism A1298C (Glu429Ala) predicts decline in renal function over time in the African-American Study of Kidney Disease and Hypertension (AASK) Trial and Veterans Affairs Hypertension Cohort (VAHC)

BACKGROUND

Hyperhomocysteinemia is associated with increased venous thrombosis and cardiovascular disease (CVD). Mutations in the human methylenetetrahydrofolate reductase (MTHFR) gene have been associated with increased homocysteine levels and risks of CVD in various populations including those with kidney disease. Here, we evaluated the influence of MTHFR variants on progressive loss of kidney function.

METHODS

We analyzed 821 subjects with hypertensive nephrosclerosis from the longitudinal National Institute of Diabetes and Digestive and Kidney Diseases African-American Study of Kidney Disease and Hypertension (AASK) Trial to determine whether decline in glomerular filtration rate (GFR) over ∼4.2 years was predicted by common genetic variation within MTHFR at non-synonymous positions C677T (Ala222Val) and A1298C (Glu429Ala) or by MTHFR haplotypes. The effect on GFR decline was then supported by a study of 1333 subjects from the San Diego Veterans Affairs Hypertension Cohort (VAHC), followed over ∼4.5 years. Linear effect models were utilized to determine both genotype [single-nucleotide polymorphism (SNP)] and genotype (SNP)-by-time interactions.

RESULTS

In AASK, the polymorphism at A1298C predicted the rate of GFR decline: A1298/A1298 major allele homozygosity resulted in a less pronounced decline of GFR, with a significant SNP-by-time interaction. An independent follow-up study in the San Diego VAHC subjects supports that A1298/A1298 homozygotes have the greatest estimated GFR throughout the study. Haplotype analysis with C677T yielded concurring results.

CONCLUSION

We conclude that the MTHFR-coding polymorphism at A1298C is associated with renal decline in African-Americans with hypertensive nephrosclerosis and is supported by a veteran cohort with a primary care diagnosis of hypertension. Further investigation is needed to confirm such findings and to determine what molecular mechanism may contribute to this association.

Association of methylenetetrahydrofolate reductase C677T polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

Background

The association of methylenetetrahydrofolate reductase (MTHFR) gene polymorphism and serum lipid profiles is still controversial in diverse ethnics. Bai Ku Yao is an isolated subgroup of the Yao minority in China. The aim of the present study was to eveluate the association of MTHFR C677T polymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

Methods

A total of 780 subjects of Bai Ku Yao and 686 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of the MTHFR C677T was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

Results

The levels of serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.05-0.001). The frequency of C and T alleles was 77.4% and 22.6% in Bai Ku Yao, and 60.9% and 39.1% in Han (P < 0.001); respectively. The frequency of CC, CT and TT genotypes was 58.7%, 37.3% and 4.0% in Bai Ku Yao, and 32.6%, 56.4% and 11.0% in Han (P < 0.001); respectively. The levels of TC and LDL-C in both ethnic groups were significant differences among the three genotypes (P < 0.05-0.01). The T allele carriers had higher serum TC and LDL-C levels than the T allele noncarriers. The levels of ApoB in Han were significant differences among the three genotypes (P < 0.05). The T allele carriers had higher serum ApoB levels as compared with the T allele noncarriers. The levels of TC, TG and LDL-C in Bai Ku Yao were correlated with genotypes (P < 0.05-0.001), whereas the levels of LDL-C in Han were associated with genotypes (P < 0.001). Serum lipid parameters were also correlated with sex, age, body mass index, alcohol consumption, cigarette smoking, and blood pressure in the both ethnic groups.

Conclusions

The differences in serum TC, TG, LDL-C and ApoB levels between the two ethnic groups might partly result from different genotypic and allelic frequencies of the MTHFR C677T or different MTHFR gene-enviromental interactions.