Role of 677C→T polymorphism a single substitution in methylenetetrahydrofolate reductase (MTHFR) gene in North Indian infertile men

Failure or severe difficulty in conceiving a child is surprisingly common, worldwide problem. Half of these cases are due to male factors with defects in sperm (1 in 15 men) being the single most common cause. Also about 60–75 % of male infertility cases are idiopathic, since the molecular mechanisms underlying the defects remain unknown. DNA methylation is crucial for spermatogenesis and high methylenetetrahydrofolate reductase (MTHFR) activity in adult testis than other organs in mouse, signifies its critical role in spermatogenesis. According to recent findings there is a correlation of epigenetic regulation of several imprinted genes with disturbed spermatogenesis and fertility. Consequently any change in the MTHFR gene sequence can modify the spermatogenesis including transmission of infertility to the carriers. The aim of the study is to analyze the distribution of the single nucleotide polymorphism C677T in the MTHFR gene in 637 North Indian infertile patients and 364 fertile North Indian men as controls by using PCR–RFLP technique and Chi Square test for statistical analysis. The average MTHFR 677CC, 677CT, 677TT genotype frequencies of total infertile men were 70.17, 24.17, 5.65 % in infertile men and 75.27, 21.7, 2.74 % in controls, respectively. The average frequency of the MTHFR 677T allele was 17.73 % in infertile men as compared to 13.59 % in controls. The statistical difference was significant. Disease risk was found 2.27-folds increased in patients who were carrying T allele. We found an association of C677T polymorphism with male infertility and that it may be a genetic risk factor for male infertility in North Indian population.     

Association of the MTHFR A1298C variant with unexplained severe male infertility

The methylenetetrahydrofolate reductase (MTHFR) gene is one of the main regulatory enzymes involved in folate metabolism, DNA synthesis and remethylation reactions. The influence of MTHFR variants on male infertility is not completely understood. The objective of this study was to analyze the distribution of the MTHFR C677T and A1298C variants using PCR-Restriction Fragment Length Polymorphism (RFLP) in a case group consisting of 344 men with unexplained reduced sperm counts compared to 617 ancestry-matched fertile or normozoospermic controls. The Chi square test was used to analyze the genotype distributions of MTHFR polymorphisms. Our data indicated a lack of association of the C677T variant with infertility. However, the homozygous (C/C) A1298C polymorphism of the MTHFR gene was present at a statistically high significance in severe oligozoospermia group compared with controls (OR = 3.372, 95% confidence interval CI = 1.27–8.238; p = 0.01431). The genotype distribution of the A1298C variants showed significant deviation from the expected Hardy-Weinberg equilibrium, suggesting that purifying selection may be acting on the 1298CC genotype. Further studies are necessary to determine the influence of the environment, especially the consumption of diet folate on sperm counts of men with different MTHFR variants.     

Strong association of 677 C>T substitution in the MTHFR gene with male infertility--a study on an indian population and a meta-analysis

Background

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme of folate and methionine metabolism, making it crucial for DNA synthesis and methylation. The objective of this study was to analyze MTHFR gene 677C>T polymorphism in infertile male individuals from North India, followed by a meta-analysis on our data and published studies.

Methodology/Principal Findings

We undertook genotyping on a total of 837 individuals including well characterized infertile (N = 522) and confirmed fertile (N = 315) individuals. The SNP was typed by direct DNA sequencing. Chi square test was done for statistical analysis. Published studies were searched using appropriate keywords. Source of data collection for meta-analysis included ‘Pubmed’, ‘Ovid’ and ‘Google Scholar’. Those studies analyzing 677C>T polymorphism in male infertility and presenting all relevant data were included in meta-analysis. The genotype data for infertile subjects and fertile controls was extracted from each study. Chi square test was done to obtain odds ratio (OR) and p-value. Meta-analysis was performed using Comprehensive Meta-analysis software (Version 2). The frequency of mutant (T) allele (p = 0.0025) and genotypes (CT+TT) (p = 0.0187) was significantly higher in infertile individuals in comparison to fertile controls in our case-control study. The overall summary estimate (OR) for allele and genotype meta-analysis were 1.304 (p = 0.000), 1.310 (p = 0.000), respectively, establishing significant association of 677C>T polymorphism with male infertility.

Conclusions/Significance

677C>T substitution associated strongly with male infertility in Indian population. Allele and genotype meta-analysis also supported its strong correlation with male infertility, thus establishing it as a risk factor.     

Antioxidant levels in blood and seminal plasma and their impact on sperm parameters in infertile men

Excess reactive oxygen species (ROS) beyond the scavenging capacity of antioxidants leads to DNA damage and oxidation of lipoprotein components at the cellular and subcellular level. The oxidative stress (OS) adversely affects sperm function by altering membrane fluidity, permeability and impairs sperm functional competence. In the present study, the OS status in seminal plasma and blood serum in infertile men and its relationship with spermatozoa parameters have been investigated. Four groups of infertile men viz., oligozoospermic (n = 15), asthenozoospermic (n = 17), teratozoospermic (n = 19), and oligoasthenoteratozoospermic (n = 9), and healthy fertile controls (n = 40) have been analyzed for superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA) in seminal plasma and blood serum. Significant correlation between blood serum SOD and sperm count has been observed in patients (p = 0.018) and controls (p = 0.021). Similarly, significant correlation between blood serum GSH and sperm progressive motility in patients (p = 0.036) and controls (p = 0.029) is observed. The low seminal MDA is associated with increase in sperm progressive motility in patients (p = 0.039) and controls (p = 0.028). Positive correlation is found between increased seminal MDA levels and abnormal sperm morphology in both patients and controls (r = 0.523, p = 0.029; r = 0.612, p = 0.034 respectively). Correlations between blood SOD and sperm count and between blood GSH levels and progressive motility suggest that these can be important biochemical markers in assaying the sperm count and motility. A negative correlation of motility with seminal MDA indicates that sperm membrane lipid peroxidation affects the fluidity and thus mobility of sperm axoneme. This affects functional competence of the sperm and acts like a biological safeguard. The results of the present study suggest the prospects of using the blood serum and seminal plasma antioxidants as a valuable tool to evaluate the sperm reproductive capacity and functional competence.     

An ADP-ribosyltransferase 3 (ART3) variant is associated with reduced sperm counts in Czech males: case/control association study replicating results from the Japanese population

OBJECTIVES: In about 50% of male infertility the underlying pathogenesis remains unknown. A recent Japanese study provided evidence that the rs6836703: G>A single-nucleotide polymorphism (SNP) from the ADP-ribosyltransferase 3 (ART3) gene is significantly associated with non-obstructive azoospermia. However, the functional significance of this association is unknown and replication studies in unrelated populations are thus necessary. Design: In this study, 257 fertile Czech controls of proven paternity and 98 sub-/infertile patients selected according to stringent exclusion / inclusion criteria were genotyped by High Resolution Melting (HRM) of small amplicons. Setting: This study was performed at University Hospital Motol - Laboratory of reproductive genetics using routinely analyzed cases. Results: Significant differences in allele distribution between fertile and sub-/infertile men were found (OR=1.78, 95% CI: 1.17-2.70; p=0.007). Following sub-stratification of cases according to their sperm counts we found that observed differences in allele distributions were increased in oligozoospermic men with sperm counts of <15 million sperm/mL (OR=1.98, 95% CI: 1.28-3.07; p=0.002). This difference was also reflected in genotype distributions between fertile and sub-/infertile men (p=0.008), and fertile versus oligozoospermic men (p=0.004). Conclusions: Our study serves as a first replication of the original Japanese report and opens new avenues of research. Compared to the Japanese patient cohort, we provided evidence that the analyzed ART3 variant is associated with quantitative impairment of spermatogenesis.     

亚甲基四氢叶酸还原酶基因C677T、G1793A 单核苷酸多态性 与散发性乳腺癌易感性的关系

目的:研究亚甲基四氢叶酸还原酶(MTHFR)基因C677T、G1793A位点单核苷酸多态性与散发性乳腺癌易感性关系。方法:采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)方法,对200例乳腺癌患者及200例正常对照者MTHFR基因C677T、G1793A位点单核苷酸多态性进行分析,logistic回归分析不同基因型与乳腺癌风险的关系。结果:乳腺癌组MTHFR 677TT基因型频率为25.00%显著高于正常对照组的10.50%(X2=14.401,P=0.001),CT基因型频率为44.50%低于正常对照组的54.50%,CC基因型频率在乳腺癌组和正常对照组中无差别;MTHFR 1793GA基因型频率为18.50%显著高于正常对照者的8.50%(X2=8.563,P=0.003)。乳腺癌患者MTHFR 677T和1793A等位基因频率分别为47.25%、9.25%,显著高于对照组中的37.75%、4.25%。MTHFR 677TT基因型携带者罹患乳腺癌的风险是677CC基因型携带者的2.732倍(95%CI=1.418～5.051,P=0.001),MTHFR1793GA基因型携带者罹患乳腺癌的风险是1793GG基因型携带者的2.444倍(95%CI=1.325～4.505,P=0.003)。另外,乳腺癌组中MTHFR C677T基因多态性与肿瘤大小相关(x2=7.431,P=0.024,MTHFR G1793A基因多态性与淋巴结转移情况(x2=8.939,P=0.011)、癌组织学分级(x2=9.983,P=0.007)相关。结论:MTHFR C677T、G1793A基因多态性与散发性乳腺癌的易感性相关。     

亚甲基四氢叶酸还原酶基因C677T、G1793A单核苷酸多态性与散发性乳腺癌易感性的关系

目的：研究亚甲基四氢叶酸还原酶（MTHFR）基因C677T、G1793A位点单核苷酸多态性与散发性乳腺癌易感性关系。方法：采用聚合酶链反应-限制性片段长度多态性（PCR-RFLP）方法,对200例乳腺癌患者及200例正常对照者MTHFR基因C677T、G1793A位点单核苷酸多态性进行分析,logistic回归分析不同基因型与乳腺癌风险的关系。结果：乳腺癌组MTHFR 677TT基因型频率为25.00%显著高于正常对照组的10.50%（X2=14.401,P=0.001）,CT基因型频率为44.50%低于正常对照组的54.50%,CC基因型频率在乳腺癌组和正常对照组中无差别;MTHFR 1793GA基因型频率为18.50%显著高于正常对照者的8.50%（X2=8.563,P=0.003）。乳腺癌患者MTHFR 677T和1793A等位基因频率分别为47.25%、9.25%,显著高于对照组中的37.75%、4.25%。MTHFR 677TT基因型携带者罹患乳腺癌的风险是677CC基因型携带者的2.732倍（95%CI=1.418～5.051,P=0.001）,MTHFR1793GA基因型携带者罹患乳腺癌的风险是1793GG基因型携带者的2.444倍（95%CI=1.325～4.505,P=0.003）。另外,乳腺癌组中MTHFR C677T基因多态性与肿瘤大小相关（x2=7.431,P=0.024,MTHFR G1793A基因多态性与淋巴结转移情况（x2=8.939,P=0.011）、癌组织学分级（x2=9.983,P=0.007）相关。结论：MTHFR C677T、G1793A基因多态性与散发性乳腺癌的易感性相关。     

The common MTHFR C677T and A1298C variants are not associated with the risk of non-syndromic cleft lip/palate in northern Venezuela

Non-syndromic cleft lip with or without cleft palate （nsCL/P） is among the most common major birth defects, with complex inheritance involving multiple genes and environmental factors. Numerous studies of MTHFR, encoding methylenetetrahydrofolate reductase, which catalyzes the rate-limiting step of folic acid biosynthesis, have shown inconsistent association of two common hypomorphic allelic variants, C677T and A1298C, in nsCL/P patients and, in some cases, their mothers. We have studied the MTHFR C677T and A1298C polymorphisms in nsCL/P patients, their mothers, and population-matched controls from northern Venezuela. We found no evidence for contribution of the MTHFR C677T and A1298C variants to the risk of nsCL/P in northern Venezuela. Overall, our findings fail to support a causal role of either the MTHFR C677T or A 1298C variants in the pathogenesis of nsCL/P in northern Venezuela.     

Variants in endothelial nitric oxide synthase (eNOS) gene in idiopathic infertile Brazilian men

Purpose

In recent years, considerable concern has been expressed about the deleterious effects of reactive oxygen species (ROS) on sperm function, because ROS at high levels is potentially detrimental to sperm function and quality. Nitric oxide (NO) is a powerful anti-oxidant present in seminal plasma. The aim of the study was to analyze the distribution of the of endothelial nitric oxide synthase (eNOS) gene (T-786C, G894T, e 4a/b) polymorphisms in idiopathic infertile Brazilian men and evaluate the possible role of these polymorphisms in sperm count.

Methods

A case–control study was performed comprising 208 infertile men [n = 74 with non-obstructive azoospermia and n = 134 with severe oligozoospermia] and 201 fertile men as controls. Genotyping of eNOS polymorphisms was performed by real time (T-786C and G894T) and conventional PCR (4a/b). The results were analyzed statistically and a p-value < 0.05 was considered significant.

Results

According to the sperm count, relatively similar eNOS polymorphism genotypes and allele frequencies were found among the groups. Combined genotypes of the eNOS polymorphisms did not identify a haplotype associated with idiopathic infertility, even when the patients were separated in non-obstructive azoospermia or severe oligozoospermia.

Conclusion

In conclusion, the findings demonstrate that, in Brazilian population studied, genetic variations, T-786C, G894T, and e 4a/b, of the eNOS gene are not associated with male infertility.     

The relationship between anogenital distance, fatherhood, and fertility in adult men

Background

Anogenital distance (AGD), a sexually dimorphic measure of genital development, is a marker for endocrine disruption in animal studies and may be shorter in infant males with genital anomalies. Given the correlation between anogenital distance and genital development, we sought to determine if anogenital distance varied in fertile compared to infertile adult men.

Methods

A cross sectional study of consecutive men being evaluated for infertility and men with proven fertility was recruited from an andrology clinic. Anogenital distance (the distance from the posterior aspect of the scrotum to the anal verge) and penile length (PL) were measured using digital calipers. ANOVA and linear regression were used to determine correlations between AGD, fatherhood status, and semen analysis parameters (sperm density, motility, and total motile sperm count).

Findings

A total of 117 infertile men (mean age: 35.3±17.4) and 56 fertile men (mean age: 44.8±9.7) were recruited. The infertile men possessed significantly shorter mean AGD and PL compared to the fertile controls (AGD: 31.8 vs 44.6 mm, PL: 107.1 vs 119.5 mm, p<0.01). The difference in AGD persisted even after accounting for ethnic and anthropomorphic differences. In addition to fatherhood, on both unadjusted and adjusted linear regression, AGD was significantly correlated with sperm density and total motile sperm count. After adjusting for demographic and reproductive variables, for each 1 cm increase in a man''s AGD, the sperm density increases by 4.3 million sperm per mL (95% CI 0.53, 8.09, p = 0.03) and the total motile sperm count increases by 6.0 million sperm (95% CI 1.34, 10.58, p = 0.01). On adjusted analyses, no correlation was seen between penile length and semen parameters.

Conclusion

A longer anogenital distance is associated with fatherhood and may predict normal male reproductive potential. Thus, AGD may provide a novel metric to assess reproductive potential in men.     

Study of the effects of oral zinc supplementation on peroxynitrite levels, arginase activity and NO synthase activity in seminal plasma of Iraqi asthenospermic patients

Background

Low concentrations of nitric oxide (NO) are necessary for the biology and physiology of spermatozoa, but high levels of NO are toxic and have negative effects on sperm functions. Although several studies have considered the relationship between infertility and semen NO concentrations, no study on the effects of asthenospermia treatments such as oral zinc supplementation on concentrations of NO, which are important in fertility, has been reported. Studies have shown that oral zinc supplementation develops sperm count, motility and the physical characteristics of sperm in animals and in some groups of infertile men. The present study was conducted to study the effect of zinc supplementation on the quantitative and qualitative characteristics of semen, along with enzymes of the NO pathway in the seminal plasma of asthenospermic patients.

Methods

Semen samples were obtained from 60 fertile and 60 asthenozoospermic infertile men of matched age. The subfertile group was treated with zinc sulfate; each participant took two capsules (220 mg per capsule) per day for 3 months. Semen samples were obtained (before and after zinc sulfate supplementation). After liquefaction of the seminal fluid at room temperature, routine semen analyses were performed. The stable metabolites of NO (nitrite) in seminal plasma were measured by nitrophenol assay. Arginase activity and NO synthase activity were measured spectrophotometrically.

Results

Peroxynitrite levels, arginase activity, NO synthase activity and various sperm parameters were compared among fertile controls and infertile patients (before and after treatment with zinc sulfate). Peroxynitrite levels and NO synthase activity were significantly higher in the infertile patients compared to the fertile group. Conversely, arginase activity was significantly higher in the fertile group than the infertile patients. Peroxynitrite levels, arginase activity and NO synthase activity of the infertile patient were restored to normal values after treatment with zinc sulfate. Volume of semen, progressive sperm motility percentage and total normal sperm count were increased after zinc supplementation.

Conclusions

Treatment of asthenospermic patients with zinc supplementation leads to restored peroxynitrite levels, arginase activity and NO synthase activity to normal values and gives a statistically significant improvement of semen parameters compared with controls.

Trial registration

ClinicalTrials.gov identifier: NCT01684059     

Associations of variants in MTHFR and MTRR genes with male infertility in the Jordanian population

Folate pathway is expected to play an important role in spermatogenesis since it is involved in DNA synthesis, repair and methylation. The purpose of this study was to examine the association between male infertility and the MTHFR (C677T and A1298C) and MTRR (A66G) polymorphisms. A group of 300 males was recruited in this study from different Jordanian infertility clinics. Of these, 150 cases of infertile men that included oligozoospermia cases (n = 45), severe oligozoospermia (n = 71) and azoospermia (n = 34) were studied. The other 150 males were age matched fertile controls. Genotyping of MTHFR and MTRR polymorphisms was performed using PCR-RFLP technique. The results showed an association between MTHFR 677TT genotype and male infertility (P < 0.05). However, the distribution of MTHFR A1298C and MTRR A66G genotypes were not different between the fertile and infertile groups (P > 0.05). In addition, none of the examined polymorphisms was related to any of the semen parameters in the infertile group. In conclusion, this study showed that MTHFR C677T polymorphism is associated with male infertility in Jordanians.     

Association of rs1057035polymorphism in microRNA biogenesis pathway gene (<Emphasis Type="Italic">DICER1</Emphasis>) with azoospermia among Iranian population

Since genes involved in microRNA biogenesis pathways have a main role in impaired spermatogenesis, in this research, we evaluated different genotypes frequency of seven single-nucleotide polymorphisms in DICER1 and DROSHA genes. Different genotypes frequency of DICER1 (rs12323635, rs1057035, rs13078 and rs3742330) and DROSHA (rs10719, rs642321 and rs2291102) were determined by sequencing method in 385 infertile men and 120 fertile controls. It was found that CC genotype (P?=?0.000) and C allele (P?=?0.0) of rs1057035 T?>?C polymorphism were associated with idiopathic male infertility (azoospermia). Gene expression study in blood and testis samples was done by real time PCR technique. Our results showed significant under expression of DICER1 gene in blood and testis tissues of azoospermic samples (P?<?0.05), but we did not observed significant difference in expression ratio between infertile men with and without C allele of rs1057035 SNP (P?>?0.05). The results of this study showed that among the studied variants, only one of them in DICER1 might be associated with azoospermia, but additional studies needs in different populations and ethnics.     

MTHFR 677C>T Polymorphism and the Risk of Breast Cancer: Evidence from an Original Study and Pooled Data for 28031 Cases and 31880 Controls

Background

Methylenetetrahydrofolate reductase (MTHFR) acts at an important metabolic point in the regulation of cellular methylation reaction. It assists in the conversion of 5, 10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. The latter aids in remethylation of homocysteine to de novo methionine that is required for DNA synthesis. The objective of this study was to examine the effect of MTHFR 677 C>T polymorphism on the risk of breast cancer in the Indian sub-continent.

Methods and Results

We genotyped 677 C>T locus in 1096 individuals that were classified into cases (N=588) and controls (N=508). Genotype data were analyzed using chi-square test. No significant difference was observed in the distribution of genotypes between cases and controls in north Indian (P = 0.932), south Indian (P = 0.865), and pooled data (P = 0.680). To develop a consensus regarding the impact of 677C>T polymorphism on breast cancer risk, we also conducted a meta-analysis on 28031 cases and 31880 controls that were pooled from sixty one studies. The overall summary estimate upon meta-analysis suggested no significant correlation between the 677C>T substitution and breast cancer in the dominant model (Fixed effect model: OR = 0.97, P=0.072, Random effects model: OR = 0.96, P = 0.084) or the recessive model (Fixed effect model: OR = 1.05, P = 0.089; Random effects model: OR= 1.08, P= 0.067).

Conclusion

677 C>T substitution does not affect breast cancer risk in the Indo-European and Dravidian populations of India. Analysis on pooled data further ruled out association between the 677 C>T polymorphism and breast cancer. Therefore, 677 C>T substitution does not appear to influence the risk of breast cancer.     

Methylenetetrahydrofolate reductase C677T polymorphism in patients with gastric and colorectal cancer

This study was designed to investigate, in the Turkish population, an association of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of gastric and colorectal cancer. Our study was carried out in 35 patients with gastric cancer (20 men, 15 women) and 144 controls (75 men, 69 women) and 52 colorectal cancer (31 men, 21 women). MTHFR C677T genotypes were determined by polymerase chain reaction, restriction fragment length polymorphism techniques. No differences were observed in the distribution of MTHFR genotypes or allele frequencies in cases versus controls. The homozygous mutation (T/T) in the MTHFR gene was identified in 14.3% of gastric cancer versus 10.4% of controls. MTHFR C677T frequencies of the CC, CT and TT genotypes among colorectal cancer patients were 34.6%, 51.9% and 13.5%, respectively. MTHFR C677T polymorphism may not be important in an individual's susceptibility to gastric and colorectal cancer in Turkey and may not be a useful marker for identifying patients at high risk of developing gastric and colorectal cancer.     

Association study of protamine 2 (<Emphasis Type="Italic">PRM2</Emphasis>) gene polymorphism with male infertility in Chinese Han population

Protamine 2 (PRM2), an essential nuclear protein expressed in sperm, is known to be involved in the spermatogenesis. Although PRM2 defects have been reported to be involved in male infertility, studies for the relationship between male infertility and PRM2 polymorphisms are inconclusive. With the purpose to determine the association of PRM2 variant with male infertility in Chinese Han population, one single nucleotide polymorphism locus G398C in PRM2 which might play a role in semen quality was selected and the variant frequency was analyzed in 144 idiopathic infertile men (case group) and 111 proven-fertile men (control group) in the study. Three genotypes were discovered in the studied population and statistical analysis showed that the frequencies of GG and GC genotypes of PRM2 G398C were significantly different between the fertile and infertile men (P < 0.05) and GC genotype was associated with increased risk of male infertility (OR = 1.795, 95 % CI 1.070–3.013, P = 0.026). Further, the C allele distribution was significantly elevated in infertile group (OR = 1.484, 95 % CI 1.001–2.200, P = 0.049). Moreover, we discovered that sperm motility, progressive motility, sperm DNA integrity as well as nuclear maturity rate of GG genotype presented the highest values and were dramatically different with that of CC genotype (P < 0.05). Our results gave the first evidence that PRM2 G398C polymorphism was associated with the pathogenesis of male infertility and its genetic variation was in relation to semen quality in Chinese Han population.     

Interaction of eNOS polymorphism with MTHFR variants increase the risk of diabetic nephropathy and its progression in type 2 diabetes mellitus patients

The present study has investigated the role of endothelial nitric oxide (eNOS) G894T polymorphism and its interaction with methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C variants on the predisposition to diabetic nephropathy and its progression. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method the eNOS G894T and MTHFR polymorphisms were detected in 72 microalbuminuric, 68 macroalbuminuric, and 72 normoalbuinuric type 2 diabetes mellitus (T2DM) patients from Western Iran. The presence of GT and GT + TT genotypes of eNOS were associated with insignificantly 1.86- and 1.68-fold increased risk of macroalbuminuria, respectively and 1.21- and 1.13-fold increased risk of microalbuminuria, respectively. However, the concomitant presence of eNOST and MTHFR 1298C alleles were significantly increased the risk of macroalbuminuria (6.6-fold, P < 0.001) and progression from micro- to macro-albuminuria (3.85 times, P = 0.011). Also, the presence of both alleles of eNOST and MTHFR 677T were significantly associated with increased risk of macroalbuminuria (4.8-fold, P = 0.005). The presence of GT + TT genotypes of eNOS was significantly associated with increased risk of coronary artery disease in micro- and macro-albuminuric patients compared to normoalbuminuric patients. The concomitant presence of three mutant alleles significantly increased the risk of macroalbuminuria and progression from micro- to macro-albuminuria 38.5- and 10.5-fold, respectively. Our study indicated that eNOS T allele interacts with MTHFR variants, especially MTHFR A1298C to increase the risk of macroalbuminuria and progression from micro-to macro-albuminuria. Also, Interaction between three alleles of eNOST, MTHFR 677T, and 1298C highly increased the risk of macroalbuminuria and progression of diabetic nephropathy in T2DM patients.     

Methylenetetrahydrofolate reductase genotypes and haplotypes associated with susceptibility to colorectal cancer in an eastern Chinese Han population

Methylenetetrahydrofolate reductase (MTHFR) plays an important role in folate metabolism and is involved in DNA synthesis, DNA repair and DNA methylation. The two common functional polymorphisms of MTHFR, C677T and A1298C have been associated with several diseases, including cancer. We made a case-control study to analyze a possible association of MTHFR gene polymorphisms C677T and A1298C with risk for colorectal cancer in an eastern Chinese Han population of 137 patients with a confirmed histopathological diagnosis of CRC and 145 age- and gender-matched controls with no history of cancer. DNA was isolated from peripheral blood samples and the genotypes were determined by PCR-RFLP. The concentrations of folate in plasma were measured by chemiluminescence immunoassay. The MTHFR 677TT genotype had a protective effect against colorectal cancer, with an odds ratio (OR) = 0.467 (95% confidence interval (CI) = 0.225-0.966). The 1298CC genotype was significantly correlated with a reduced risk of colorectal cancer (OR = 0.192; 95%CI = 0.040-0.916). Compared with the MTHFR 677CC and MTHFR 1298 AA genotypes, for individuals who carried both MTHFR 677CC and 1298CC genotypes, the OR of colorectal cancer was 0.103 (95%CI = 0.012-0.900); among individuals who carried both MTHFR 677TT and 1298AC genotypes, the OR for risk of colorectal cancer was 0.169 (95%CI = 0.044-0.654). MTHFR 677TT+CT genotypes had a significantly lower plasma folate concentration than those with the MTHFR 677CC genotype. MTHFR 1298AC+CC genotypes had a lower plasma folate concentration than those with the MTHFR 1298AA genotype (P < 0.05). In conclusion, subjects with the MTHFR 677TT and MTHFR 1298CC genotypes appeared to have a significantly lower risk for colorectal cancer. MTHFR haplotypes 677CC/1298CC and 677TT/1298AC were less common in cases than in controls. These haplotypes, when compared to the most common haplotype 677CC/1298AA, were associated with a decreased risk for colorectal cancer. We conclude that plasma folate level is influenced by MTHFR genotypes.     

Association study of folate-related enzymes (MTHFR,MTR, MTRR) genetic variants with non-obstructive male infertility in a Polish population

Spermatogenesis is a process where an important contribution of genes involved in folate-mediated one-carbon metabolism is observed. The aim of the present study was to investigate the association between male infertility and the MTHFR (677C > T; 1298A > C), MTR (2756A > G) and MTRR (66A > G) polymorphisms in a Polish population. No significant differences in genotype or allele frequencies were detected between the groups of 284 infertile men and of 352 fertile controls. These results demonstrate that common polymorphisms in folate pathway genes are not major risk factors for non-obstructive male infertility in the Polish population.