Mutation C677T of methylenetetrahydrofolate reductase gene is not associated with coronary artery disease, but possibly with albuminuria, in type 2 diabetic patients

Gender, Albuminuria and Chronic Kidney Disease Progression in Treated Diabetic Kidney Disease

BACKGROUND

Women are reported to have a lower incidence of renal replacement therapy, despite a higher prevalence of chronic kidney disease (CKD).

AIM

To analyze diabetic kidney disease (DKD) progression in men and women.

METHODS

Prospective cohort: n = 261, 35% women, new consecutive nephrology DKD referrals.

RESULTS

Women smoked less and better complied with the dietary phosphate and sodium restrictions. Despite a less frequent nephrology referral, women had lower baseline albuminuria. Over a 30 ± 10-month follow-up, albuminuria decreased in women and the estimated glomerular filtration rate (eGFR) loss was slower than in men. However, the percentage of rapid progressors was similar in both sexes. The best multivariate model predicting rapid progression in men (area under curve (AUC) = 0.92) and women differed. Albuminuria and fractional excretion of phosphate (FEphosphate) were part of the men multivariable model, but not of women. The AUC for the prediction of rapid progression by albuminuria was higher in men than in women, and the albuminuria cut-off points also differed. In women, there was a higher percentage of rapid progressors who had baseline physiological albuminuria.

CONCLUSIONS

Female DKD differs from male DKD: albuminuria was milder and better responsive to therapy, the loss of eGFR was slower and the predictors of rapid progression differed from men: albuminuria was a better predictor in men than in women. Lifestyle factors may contribute to the differences.

Association of MTHFR C677T polymorphism and type 2 diabetes mellitus (T2DM) susceptibility

Introduction

Methylenetetrahydrofolate reductase (MTHFR) is essential in mediating folate metabolism, and thus plays an important role in diabetes and diabetic complications. MTHFR C677T (rs1801133 C>T) polymorphism has been proposed to be linked with type 2 diabetes mellitus (T2DM) susceptibility. However, the conclusions are inconsistent. Therefore, we rechecked their linkage aiming to obtain a more reliable estimation by performing an updated meta‐analysis.

Methods

We searched electronic databases PubMed, EMBASE, CNKI, and Wanfang to obtain studies updated to October 2019.

Results

After carefully screening, we finally incorporated 68 studies with 10,812 cases and 8,745 controls. The genotype frequency of C677T polymorphism was analyzed pooled to generate odds ratios (ORs) and 95% confidence intervals (CIs). Pooled results presented that MTHFR C677T polymorphism was significantly associated with T2DM under homozygous (OR = 1.64, 95% CI = 1.39–1.94), heterozygous (OR = 1.38, 95% CI = 1.20–1.59), recessive (OR = 1.41, 95% CI = 1.23–1.61), dominant (OR = 1.47, 95% CI = 1.27–1.70), and allele (OR = 1.37, 95% CI = 1.23–1.52) genetic models. Stratified analysis demonstrated that C677T genotype was associated with T2DM in Asian populations, but not Caucasian and African populations.

Conclusion

Our results indicated that MTHFR C677T polymorphism confers to T2DM, especially in Asian populations. Much more large‐scale case–control studies are needed to strengthen such conclusion in the future.

Familial aggregation of albuminuria and arterial hypertension in an Aboriginal Australian community and the contribution of variants in ACE and TP53

Background

Aboriginal Australians are at high risk of cardiovascular, metabolic and renal diseases, resulting in a marked reduction in life expectancy when compared to the rest of the Australian population. This is partly due to recognized environmental and lifestyle risk factors, but a contribution of genetic susceptibility is also likely.

Methods

Using results from a comprehensive survey of one community (N = 1350 examined individuals), we have tested for familial aggregation of plasma glucose, arterial blood pressure, albuminuria (measured as urinary albumin to creatinine ratio, UACR) and estimated glomerular filtration rate (eGFR), and quantified the contribution of variation at four candidate genes (ACE; TP53; ENOS3; MTHFR).

Results

In the subsample of 357 individuals with complete genotype and phenotype data we showed that both UACR (h² = 64%) and blood pressure (sBP h² = 29%, dBP, h² = 11%) were significantly heritable. The ACE insertion-deletion (P = 0.0009) and TP53 codon72 polymorphisms (P = 0.003) together contributed approximately 15% of the total heritability of UACR, with an effect of ACE genotype on BP also clearly evident.

Conclusions

While the effects of the ACE insertion-deletion on risk of renal disease (especially in the setting of diabetes) are well recognized, this is only the second study to implicate p53 genotype as a risk factor for albuminuria - the other being an earlier study we performed in a different Aboriginal community (McDonald et al., J Am Soc Nephrol 13: 677-83, 2002). We conclude that there are significant genetic contributions to the high prevalence of chronic diseases observed in this population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-016-0396-2) contains supplementary material, which is available to authorized users.

Association of ACE and MTHFR genetic polymorphisms with type 2 diabetes mellitus: Susceptibility and complications

HYPOTHESIS/INTRODUCTION

Polymorphisms of angiotensin converting enzyme (ACE) and methylene-tetrahydrofolate reductase (MTHFR) genes have been proposed to be associated with type 2 diabetes mellitus (T2DM) with conflicting results. This work was planned in order to check for the association of these polymorphisms with the susceptibility for and complications of T2DM among Egyptian cases.

MATERIALS AND METHODS

This is a case controlled study involving 203 patients with T2DM and 311 healthy controls. Polymorphic variants of ACE I>D and MTHFR (677 C>T and 1298 A>C) were determined using the polymerase chain reaction (PCR) restriction analysis technique.

RESULTS

The susceptibility to T2DM was higher among subjects having the MTHFR 677TT (odds ratio (OR)=2.2, p=0.01), MTHFR 1298 AA (OR=1.84, p=0.001) and ACE (ID+II) (OR=2.0, p=0.0007) genotypes. Logistic regression analysis showed that MTHFR 677T allele was a risk factor for diabetic retinopathy (DR) (OR=3.47, p<0.001), diabetic polyneuropathy (DPN) (OR=5.2, p<0.0001) and ischemic heart disease (IHD) (OR=2.9, p<0.05), while MTHFR 1298 C allele was a risk factor for DR (OR=4.2, p<0.001) and the ACE DD genotype was a risk factor for DPN (OR=3.1, p<0.001).

CONCLUSIONS

The MTHFR 677 TT genotype was associated with T2DM susceptibility and complications (DR, DPN and IHD). The MTHFR 1298 CC, AC and ACE DD genotypes were associated with DR and DPN.

Folate intake, plasma folate and homocysteine status in a random Finnish population

OBJECTIVE

To assess the folate status of Finnish adults using plasma folate and homocysteine as biomarkers and to evaluate dietary and supplementary folate intakes.

MATERIALS AND METHODS

Plasma folate, vitamin B(12) and total homocysteine (tHcy) were determined in a random sample of 643 subjects aged 25-74 y living in the Helsinki area. The methylenetetrahydrofolate reductase (MTHFR)-genotypes were analyzed from a subsample (n=394). Dietary intake data by 24 h recall and use of vitamin supplements were collected.

RESULTS

Plasma folate was normal (>/=5 nmol/l) in 99% of subjects and optimal (>/=8 nmol/l) in terms of a minimum tHcy in 90%. Mean plasma folate of non-supplement users was 13.7 and 12.9 nmol/l and tHcy 11.3 and 9.2 micro mol/l for men and women, respectively. Elevated tHcy (>14 micro mol/l) was found in 11% of subjects. Homozygote frequency for MTHFR genotype TT was 5.0% and their plasma tHcy was 14.8 micro mol/l compared to the mean of the other subjects, 10.5 micro mol/l, P<0.05. The mean dietary folate intake was 241 micro g/day (29 micro g/MJ of energy) for men and 205 micro g/day (33 micro g/MJ) for women, respectively. The main dietary sources of folate were vegetables 12%, wholemeal ryebread 11%, fruits 10%, and potato 10%. Regular supplement users (n=97) received on average 207 micro g folic acid per day from supplements.

CONCLUSIONS

The folate status of Finnish adults seems to be adequate according to energy adjusted folate intake, plasma folate and homocysteine. The MTHFR homozygote frequency was low compared to other countries. Regular use of supplementary folic acid less than 300 micro g increased plasma folate, but supplemental folic acid over 300 micro g was required to lower tHcy values significantly.

Methylenetetrahydrofolate reductase gene C677T mutation is related to the defects in the internal elastic lamina of the artery wall

BACKGROUND

The C677T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene leads to C/C, C/T and T/T genotypes, which affect the plasma homocysteine concentration in humans. In mini-pigs, high serum homocysteine levels are associated with defects in the internal elastic lamina (IEL) of the artery wall, which are apparently related to the migration of smooth muscle cells into the intima during atherogenesis. We studied the association between the MTHFR genotypes and the number of gaps in the IEL in the wall of the five major abdominal arteries.

MATERIALS AND METHODS

The autopsy study included 123 subjects (90 males and 33 females) aged 18-93. For the light microscopy, a 0.5 cm circular segment of the coeliac, the superior mesenteric, the inferior mesenteric and the renal arteries were cut and embedded in paraffin blocks. The circumference of the IEL, the thickness of the intima and the number of the gaps per millimetre in the IEL were measured by MOP 3 image analysis.

RESULTS

The T-allele carriers (C/T and T/T) of the MTHFR gene had significantly less gaps in the IEL than the subjects with the C/C genotype in the superior mesenteric and in the left renal arteries (2.02 +/- 2.25 vs. 2.53 +/- 1.89, P < 0.04 and 0.56 +/- 1.09 vs. 1.82 +/- 2.66, P < 0.02, respectively). The trend was similar for the coeliac and the right renal arteries.

CONCLUSIONS

Our result suggests that MTHFR polymorphism may be involved in the fragmentation of the IEL.

Plasma total homocysteine concentration and the risk of acute coronary events: the Kuopio Ischaemic Heart Disease Risk Factor Study

OBJECTIVES

Results from prospective studies concerning the association between plasma total homocysteine (tHcy) concentration and coronary heart disease (CHD) are conflicting. The purpose of this study was to test the hypothesis that plasma tHcy is associated with an increased risk of acute coronary events in middle-aged men.

DESIGN AND SUBJECTS

We investigated this association in a prospective nested case-control study among Eastern Finnish men aged 42-60 years. Plasma tHcy measurements were carried out for 163 men who had an acute coronary event during an average 8 years and 11 months follow-up of the whole cohort and for 163 control subjects. Both the cases and the controls were from a cohort of 2005 men who had no clinical CHD at the Kuopio Ischaemic Heart Disease (KIHD) baseline.

RESULTS

Men in the highest plasma tHcy concentration quarter had no increase in the risk of coronary events compared with men with lower tHcy concentrations (odds ratio = 0.88, 95% confidence interval 0.44-1.76). Average follow-up time before the first coronary event was 4.9 years (SD 3.2) in men in the highest plasma tHcy quarter and 5.5 years (SD 3.1) in men in the three lowest quarters (P = 0.368).

CONCLUSION

We conclude that plasma tHcy is not associated with an increased risk of coronary events in the middle-aged male population in eastern Finland.