Methylenetetrahydrofolate reductase C677T polymorphism is not associated with male infertility in a South Indian population

Previous studies have revealed that genetic factors may be involved in regulating the mechanism of infertility, e.g., MTHFR gene polymorphism in the development of male infertility. The aim of this study is to examine whether an association exists between MTHFR C677T polymorphism and male infertility. The study was carried out by means of a PCR-RFLP assay in 206 infertile men and 230 ethnically matched controls. The statistical analysis using two-sided Fisher's exact test and Pearson chi-squared test showed CT genotype is associated nonsignificantly with male infertility (OR = 1.19, 95% CI = 0.71-1.97). Because of the lack of TT homozygotes in the controls, a combined odds ratio of CT and TT homozygotes against the control has been calculated (OR = 1.36, 95% CI = 0.83-2.22), and the same was insignificant. The overall results of the study indicate that MTHFR C677T polymorphism is not associated with male infertility.     

Methylenetetrahydrofolate reductase C677T polymorphism and the risk of male infertility: a meta-analysis

Several molecular epidemiological studies have been conducted to examine the association between MTHFR C677T polymorphism and male infertility susceptibility, but the results remain inconsistent. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 10 case-control studies, including 2275 cases and 1958 controls, were selected. Crude odds ratios (ORs) with 95% confidence intervals were used to assess the strength of association in the additive model, dominant model and recessive model. In the overall analysis, no significant association between the polymorphism and risk of male infertility was observed. Stratified analysis showed that significantly strong association between MTHFR C677T polymorphism and male infertility were present only in Asians (OR = 1.79 for TT vs. CC genotype; OR = 1.42 for CT/TT vs. CC genotype; OR = 1.50 for TT vs. CC/CT genotype; OR = 1.36 for T vs. C allele), but not in Caucasians. Additionally, MTHFR 677T was associated with a significant increase in the risk of azoospermia in all genetic models. No significantly increased risks of oligoasthenoteratozoospermia were found in any of the genetic models. In conclusion, this meta-analysis supports that MTHFR C677T polymorphism is capable of causing male infertility susceptibility in Asians, but not in Caucasians.     

Association of the methylenetetrahydrofolate reductase gene C677T polymorphism with the risk of male infertility: a meta-analysis

Several molecular epidemiological studies have been conducted to examine the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and male infertility susceptibility, but the results remain inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. In this meta-analysis, a total of 26 case–control studies including 5659 infertility cases and 5528 controls were selected to evaluate the possible association. The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were used to assess the strength of association of C677T polymorphism with male infertility in the additive model, dominant model, recessive model and allele-frequency genetic model. In the overall analysis, the frequency of the 677T allele was significantly associated with male infertility susceptibility (OR?=?2.32, 95%CI?=?2.04–2.65 for TT vs. CC genotype; OR?=?1.09, 95%CI?=?1.00–1.19 for CT vs. CC genotype; OR?=?1.19, 95%CI?=?1.10–1.29 for CT/TT vs. CC genotype; OR?=?1.54, 95%CI?=?1.36–1.74 for TT vs. CC/TT genotype; OR?=?1.22, 95%CI?=?1.15–1.30 for T vs. C allele). A subgroup analysis of the subjects showed that significantly strong association between MTHFR C677T polymorphism and male infertility was present only in Asians, but not in Caucasians. Additionally, MTHFR C677T was associated with a significant increase in the risk of azoospermia in all genetic models. Meanwhile, no significantly increased risks of oligoasthenotertozoospermia (OAT) were found in most of the genetic models. In conclusion, this meta-analysis is in favor that the MTHFR C677T polymorphism is capable of causing male infertility susceptibility, especially in Asians and the subgroup of azoospermia.     

Association between MTHFR C677T polymorphism and diabetic nephropathy in the Chinese population: An updated meta‐analysis and review

To clarify the effects of MTHFR C677T polymorphism on the risk of diabetic nephropathy (DN) in the Chinese population, an updated meta‐analysis was performed. Related studies were identified from PubMed, Springer Link, Ovid and Chinese Databases up to 24 February 2015. A total of 15 studies including 1227 DN cases, 586 healthy controls and 1277 diabetes mellitus (DM) controls were involved in this meta‐analysis. Overall, a significantly elevated risk of DN was associated with all variants of MTHFR C677T when compared with the healthy group (T vs C, odds ratio (OR) = 2.22, 95% confidence interval (CI) = 1.88–2.61; TT vs CC, OR = 4.22, 95% CI = 3.02–5.90; TT + CT vs CC, OR = 2.62, 95% CI = 2.07–3.31; TT vs CC + CT, OR = 2.81, 95% CI = 2.08–3.81) or DM (T vs C, OR = 1.78, 95% CI = 1.59–2.00; TT vs CC, OR = 2.95, 95% CI = 2.33–3.73; TT + CT vs CC, OR = 1.93, 95% CI = 1.63–2.29; TT vs CC + CT, OR = 2.31, 95% CI = 1.87–2.84). In subgroup analyses stratified by ethnicity and geographic areas, it revealed the significant results in Chinese Han, in North and South China. The risk conferred by MTHFR C677T polymorphism is higher in North China than in South China. This meta‐analysis showed that the MTHFR C677T variants may influence DN risk in Chinese, and further studies with gene–gene and gene–environment interactions are required for definite conclusions.     

Association of methylenetetrahydrofolate reductase genetic polymorphisms with atlantoaxial dislocation

OBJECT: Genetic mechanisms of atlantoaxial dislocation (AAD) have not previously been elucidated. The authors studied association of polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, which encodes enzymes of the folate pathway (implicated in causation of neural tube defects [NTDs]), in patients with AAD. METHODS: Molecular analysis of MTHFR polymorphisms (677C-->T, cytosine to thymine and, 1298A-->C, adenine to cytosine, substitutions) was carried out using polymerase chain reaction and restriction enzyme digestion in 75 consecutive patients with AAD and in their reducible (nine patients, 12%) and irreducible (66 patients, 88%) subgroups. Controls were 60 age- and sex-matched patients of the same ethnicity. Comparisons of genotype and allele frequencies were performed using a chi-square test (with significance at p < 0.05). RESULTS: The CT genotype frequency of MTHFR 677C-->T polymorphism was significantly increased in the full group of patients with AAD (odds ratio [OR] 3.00, 95% confidence interval [CI] 1.28-7.14, p = 0.005) as well as in the irreducible subgroup (OR 2.81, 95% CI 1.17-6.86, p = 0.01). The frequency of T alleles was also higher in the AAD group (25.3%) than in controls (15%). The comparison of the combined frequency of CT and TT genotypes with the frequency of the CC genotype again showed significant association in AAD (OR 2.63, 95% CI 1.98-5.90, p = 0.009) and the irreducible (OR 2.5, 95% CI 1.1-5.74, p = 0.016) subgroup. There was, however, no significant association of MTHFR 1298A-->C polymorphism with AAD. CONCLUSIONS: Both MTHFR 677C-->T polymorphism and higher T allele frequency have significant associations with AAD, especially the irreducible variety. Perhaps adequate supplementation of periconceptional folic acid to circumvent effects of this missense mutation (as is done for prevention of NTDs) would reduce the incidence of AAD.     

MTHFR基因C677T多态性与蒙古族中老年男性骨质疏松的相关性

目的 探讨本地区蒙古族中老年男性亚甲基四氢叶酸还原酶（methylenetetrahydrofolate reductase ,MTHFR ）基因的多态性位点C677T基因多态性与内蒙古地区蒙古族中老年男性骨质疏松症(osteoporosis,OP)遗传易感性的关系。方法 收集门诊及住院蒙古族骨质疏松（包括骨质疏松性骨折）男性患者135例。对照组为按年龄配比的门诊体检内蒙古籍蒙古族中老年男性180例。入选者全部行腰椎（L2-L4）及股骨近端股骨颈骨密度扫查,并排除骨代谢疾病的影响,并进行MTHFR基因多态性检测。结果 骨质疏松组MTHFR基因受体C677T基因型CC、CT、TT频率分别为CC 25.2％、CT 40.0％和TT 34.8％;对照组基因型CC、CT、TT频率分别为31.2%,54.5%和14.3%,两组差别有统计学意义（P<0.05）。骨松组中的T等位基因频率为54.8%,显著高于对照组(41.6%,P<0.05),提示T是骨质疏松发生的危险因素(OR=1.70,95% CI=1.24～2.34,P=0.001)。与CC基因型相比,TT基因型携带者的骨松发生风险增加至2.97倍(95％ CI=2.57～5.65,P=0.001)。 结论 MTHFR基因型分布频率均符合 Hardy-Weinberg定律,T等位基因可以增加蒙古族中老年人骨折发生风险,MTHFR C677T基因变异与内蒙古地区蒙古族中老年男性骨质疏松易感性明显相关。     

Effects of the C677T and A1298C polymorphisms of the MTHFR gene on the genetic predisposition for diabetic nephropathy.

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) is a regulatory enzyme of homocysteine metabolism. The C677T polymorphism of the MTHFR gene has been reported to be associated with elevated plasma homocysteine in patients with low folic acid intake. A recently reported second common polymorphism, A1298C, may increase homocysteine, but only in individuals carrying the T677 allele. This study aimed to investigate the influence of the C677T and A1298C polymorphisms of the MTHFR gene on the development of diabetic nephropathy in Caucasian patients with type 2 diabetes. METHODS: We genotyped 429 type 2 diabetic patients for the C677T and A1298C polymorphisms using standard PCR-based protocols, and divided them into three groups based on renal status: 159 patients with normoalbuminuria, 149 with microalbuminuria, and 121 with persistent proteinuria and chronic renal failure (CRF). The C677T and A1298C genotype frequencies were compared among the three groups. RESULTS: Although the frequencies of the CT and TT genotypes of the C677T polymorphism tended to increase with each stage of diabetic nephropathy (53, 56 and 63% in normoalbuminuria, microalbuminuria and proteinuria/CRF, respectively), these differences were not significant. When male and female patients were analysed separately, the effect was seen only in males. The CT + TT genotype was present in 46% of male patients with normoalbuminuria, in 57% with microalbuminuria and in 68% with proteinuria/CRF (OR = 2.46; 95% CI 1.13-5.38). There were no differ-ences in the A1298C polymorphism among the three groups. CONCLUSIONS: These findings indicate that the C677T polymorphism is a risk factor for diabetic nephrop-athy in male patients with type 2 diabetes.     

The SPO11-C631T gene polymorphism and male infertility risk: a meta-analysis

To evaluate the association between the SPO11 gene C631T polymorphism and the risk of male infertility. We conducted a search on PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure (CNKI), China biology medical literature database (CBM), VIP, and Chinese literature database (Wan Fang) on 31 March 2016. Odds ratio (OR) and 95% confidence interval (95%CI) were used to assess the strength of associations. A total of five studies including 542 cases and 510 controls were involved in this meta-analysis. The pooled results indicated that the SPO11 gene C631T polymorphism was significantly associated with increased risk of male infertility (TT?+?CT vs. CC: OR?=?4.14, 95%CI?=?2.48–6.89; CT vs. CC: OR?=?4.34, 95%CI?=?2.56–7.34; T vs. C: OR?=?4.35, 95%CI?=?2.58–7.34). Subgroup analysis of different countries proved the relationship between SPO11 gene C631T polymorphism and male infertility risk in Chinese, but not in Iranian peoples. In conclusion, this study suggested that SPO11 gene C631T polymorphism may contribute as a genetic factor susceptible to cause male infertility. Furthermore, more large sample and representative population-based cases and well-matched controls are needed to validate our results.     

生长分化因子5 rs143383基因多态性与膝关节骨关节炎相关性的Meta分析

目的探究生长分化因子5（GDF5）rs143383基因多态性与膝关节骨性关节炎发生的相关性。 方法检索建库至2022年1月1日已经发表的关于GDF5 rs143383基因多态性与膝关节骨性关节炎之间相关性的文献,检索数据库包括PubMed、Embase、Web of Science、中国知网、万方和维普数据库等。依据检索策略检索,16篇文献（17项数据）符合纳入排除标准,从所需研究中提取数据后,确定优势比（OR）及其95%置信区间（CI）以评估。通过漏斗图评估发表偏差。 结果GDF5（rs143383）基因多态性与膝关节骨性关节炎发生之间具有明显相关性。在总体的等位基因模型（T vs C：OR=1.20,95% CI：1.14,1.26,P<0.01）、共显基因模型（TT vs CC：OR=1.45,95% CI：1.30,1.62,P<0.01）和显性基因模型（TT+TC vs CC：OR=1.29,95%CI：1.17, 1.43,P<0.01）,均提示GDF5基因多态性与膝关节骨性关节炎的发生有明显相关性。此外,我们还根据种族进行亚组分型,通过亚组分析在亚洲人群以及高加索人群的等位基因模型（亚洲人群：T vs C：OR=1.22,95% CI：1.13,1.30,P<0.01;高加索人群：T vs C：OR=1.18,95% CI：1.10,1.26,P<0.01）、共显基因模型（亚洲人群：TT vs CC：OR=1.58,95% CI：1.33,1.88,P<0.01;高加索人群：TT vs CC：OR=1.37,95% CI：1.19,1.59,P<0.01）和显性基因模型（亚洲人群：TT+TC vs CC：OR=1.40,95% CI：1.18,1.65,P<0.01;高加索人群：TT+TC vs CC：OR=1.24,95% CI：1.08,1.42,P<0.01）中均观察到了GDF5 rs143383基因多态性与膝关节骨性关节炎发生显著的关联,然而在非洲人群中无明显关联。 结论GDF5 rs143383基因多态性与膝关节骨性关节炎发生具有显著联系,尤其在亚洲人群和高加索人群中具有相关性。     

eNOS gene T786C,G894T and 4a4b polymorphisms and male infertility susceptibility: a meta‐analysis

The association between polymorphism of eNOS and male infertility in several studies was controversial. To explore a more precise estimation of the association, a meta‐analysis of eight case–control studies, including 1,968 cases and 1,539 controls, were selected. The meta‐analysis was conducted by calculating the pooled odds ratio (OR) with a 95% confidence interval (95% CI). Overall, the association between T786C and risk of male infertility was obvious (TC vs. TT: OR, 1.20; 95% CI, 1.01–1.42; CC vs. TT: OR, 3.37; 95% CI, 1.65–6.87; TC/CC vs. TT: OR, 1.47; 95% CI, 1.25–1.73; CC vs. TT/TC: OR, 3.18; 95% CI, 1.54–6.56; TC vs. TT: OR, 1.65; 95% CI, 1.27–2.03). However, no overall association was observed between the other two polymorphisms of eNOS (G894T and 4a4b) and male infertility. Stratified analysis showed that significantly strong association between T786C polymorphism and semen quality was present in all three types of male infertility (azoospermia, oligozoospermia and asthenozoospermia). In the subgroup analysis based on ethnicity, both T786C and 4a4b could influence the risk of male infertility in Asian and Caucasian. Further studies of polymorphisms of eNOS with their biological functions are needed to understand the role in the development of male infertility.     

A single-nucleotide polymorphism in TP53 may be a genetic risk factor for Iranian patients with idiopathic male infertility

Male infertility is a heterogeneous disorder that contributes to the impairment of spermatogenesis. The purpose of this study was to assess whether tumour suppressor p53 gene (Tp53) polymorphism is associated with idiopathic male infertility in the Iranian population. The prevalence of G → C substitution at codon 72 in exon 4 was determined in 110 idiopathic infertile azoo-/oligospermic patients and 180 fertile healthy control men. PCR-restriction fragment polymorphism analysis was employed to determine the genotypes. PCR amplicons were subjected to restriction digestion with Bstu1 and separated by gel electrophoresis. The Arg/Arg genotype was found more frequently among men with idiopathic infertility (32.7%) than among controls (17.7%). No significant difference was observed between Pro/Pro genotype and Arg/Arg + Arg/Pro genotypes among men with idiopathic infertility and controls (P = 0.11; OR: 0.36; 95% CI: 0.36-1.10). In contrast, a significant difference was observed in the comparison of the Arg/Arg genotype and Arg/Pro + Pro/Pro genotypes among patients and controls (P = 0.004; OR: 2.25; 95% CI: 1.29-3.90). Allele frequency evaluation suggested a significantly higher incidence of the Arg allele among infertile men compared with controls (56% versus 44%; OR: 1.6; 95% CI: 0.92-2.80). In conclusion, arginine allele appears to be at greater risk of developing idiopathic infertility in Iranian men.     

Mutation C677T in the methylenetetrahydrofolate reductase gene is associated with male infertility in an Indian population

A mutation (C677T) in the gene, MTHFR, is known to increase susceptibility to various multifactorial disorders. In order to assess this single nucleotide polymorphism (SNP) as risk factor for idiopathic male infertility, a case-control study was done on an Indian population. DNA from 151 cases of non-obstruction, idiopathic oligo-/azoospermia and 200 fertile males (controls) was polymerase chain reaction amplified using site-specific primers, and analysed for the mutation following HinfI-digestion. Our results show a significantly increased frequency of CT heterozygotes among infertile patients (p value <0.04). More importantly, while there were no T homozygotes in the control population, six of 151 infertile cases were T homozygous. Considering that T allele occurs in very low frequency in the control population, 677T is clearly a risk factor for infertility in the Indian population. We contend that the same could also be true for African and Southeast Asian populations where the frequency of 677T is very low. The lack of similar association in western populations could be because of the overall dietary enrichment of folates, which could nullify or minimize the effect of this polymorphism.     

The relationship between methylenetetrahydrofolate reductase c.677TT genotype and oligozoospermia in infertile male patients living in the Trakya region of Turkey

Methylenetetrahydrofolate reductase (MTHFR), the key enzyme of the folate metabolic pathway, has been reported to be five times more active in the testicles compared to other organs in adult mice. The aim of this study was to investigate the relationship between MTHFR c.677C>T and c.1298A>C polymorphisms and infertility in nonobstructive azoospermic and oligozoospermic male patients living in the Trakya region of Turkey. The study population included 75 nonobstructive azoospermic and 62 oligozoospermic, nonconsanguineous patients who were referred to the Department of Medical Genetics of Trakya University between 01.03.2012 and 01.06.2013 due to infertility and who had been diagnosed based on clinical examinations and spermiograms. All of the patients had a normal karyotype without a Y chromosome microdeletion. Melting curve analysis with labelled probes and primers that were designed by the manufacturers and the real‐time polymerase chain reaction method were used. The MTHFR c.677TT genotype frequency in the oligozoospermic infertile male patient group was greater than that of the fertile control group [odds ratio (OR) = 2.675 (95% CI: 0.979–7.305), (P < 0.048)]. The MTHFR c.677TT genotype may be a genetic risk factor for oligozoospermic infertile male patients who live in the Trakya region of Turkey.     

Association of the methylenetetrahydrofolate reductase C677T polymorphism and fracture risk in Chinese postmenopausal women

Osteoporotic fractures are a leading cause of disability and, indirectly, of death in the elderly population. Previous studies have shown that homocysteine level and the C677T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR) may be involved in the development of osteoporosis and its related fracture in European populations. The aim of this study was to verify the association of this polymorphism with bone mineral density (BMD) and fractures in our 1899 Chinese postmenopausal women. The C677T T allele frequency in this population was 39.2%. The distribution of the MTHFR genotypes followed the Hardy-Weinberg equilibrium. BMD at total body, total hip or femoral neck did not significantly vary with MTHFR C677T genotype. The T allele carrier tended to have higher risk of having osteoporosis or osteopenia, but the difference was statistically insignificant. However, Poisson regression analysis revealed that the T allele carriers had an increased risk of fractures (RR=1.7, 95% CI=1.1-2.7, p=0.01) which occurred before or after menopause. As far as fracture incidence after menopause was concerned, the CT or TT genotype had more than twice the risk of the CC genotype (RR=2.5, 95% CI=1.2-4.9, p=0.009). This association was independent of age, physical activity, occupation, passive smoking, height, weight, years since menopause, and total hip BMD. Our data show that the MTHFR C677T polymorphism is an independent predictor of fracture risk, although it only had a weak effect on BMD. Further study on the mechanistic role that this polymorphism plays in the development of fractures may lead to better understanding of the etiology of osteoporotic fracture.     

CAG-repeat variant in the polymerase γ gene and male infertility in the Chinese population： a meta-analysis

Several studies have reported a relationship between the length of the CAG-repeat in the polymerase γ (POLG) gene and male infertility. However, other studies have not reproduced this result. In our study, the POLG-CAG-repeat length was analyzed in 535 healthy individuals from six Chinese Han populations living in different provinces. The frequencies of 10-CAG alleles and genotypes were high (97.38 and 94.13%, respectively), with no significant difference among the six Chinese Han populations. Furthermore, we determined the distribution of the POLG-CAG-repeat in 150 infertile men and 126 fertile men. Our study suggested that the distributions of POLG-CAG-repeat alleles and genotypes were not significantly different between infertile (95.67 and 92.67%, respectively) and fertile men (97.22 and 94.44%, respectively). In a subsequent meta-analysis, combining our data with data from previous studies, a comparison of the CAG-repeat alleles in fertile versus infertile men showed no obvious risk for male infertility associated with any particular allele (pooled odds ratio (OR)=0.94; 95% confidence interval (CI): 0.60-1.48). The significance level was not attained with any of the following genetic models: homozygote comparison (not 10/not 10 versus 10/10: OR=1.34; 95% CI: 0.66-2.72), heterozygote comparison (10/not 10 versus 10/10: OR=1.04; 95% CI: 0.78-1.38), dominant model comparison (not 10/not 10+10/not 10 versus 10/10: OR=1.08; 95% CI: 0.79-1.47) and recessive genetic comparison (not 10/not 10 versus 10/not 10+10/10: OR=1.31; 95% CI: 0.68-2.55). In conclusion, there is no significant difference of the frequencies of POLG-CAG-repeat variants among six Chinese Han populations, and this polymorphism may not be associated with Chinese male infertility. On the basis of a meta-analysis, there is no obvious association between CAG-repeat variants of the POLG gene and male infertility.     

Effect of MTHFR 677C>T on plasma total homocysteine levels in renal graft recipients

BACKGROUND: Hyperhomocysteinemia is an established, independent risk factor for vascular disease morbidity and mortality. The 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism C677T has been shown to result in increased total homocysteine concentrations on the basis of low folate levels caused by a decreased enzyme activity. The effect of this polymorphism on total homocysteine and folate plasma levels in renal transplant patients is unknown. METHODS: We screened 636 kidney graft recipients for the presence of the MTHFR C677T gene polymorphism. The major determinants of total homocysteine and folate plasma concentrations of 63 patients, who were identified to be homozygous for this gene polymorphism compared with heterozygotes (N = 63), and patients with wild-type alleles (N = 63), who were matched for sex, age, glomerular filtration rate (GFR), and body mass index, were identified by analysis of covariance. The variables included sex, age, GFR, body mass index, time since transplantation, folate and vitamin B12 levels, the use of azathioprine, and the MTHFR genotype. To investigate the impact of the kidney donor MTHFR genotype on total homocysteine and folate plasma concentrations, a similar model was applied in 111 kidney graft recipients with stable graft function, in whom the kidney donor C677T MTHFR gene polymorphism was determined. RESULTS: The allele frequency of the C677T polymorphism in the MTHFR gene was 0.313 in the whole study population [wild-type (CC), 301; heterozygous (CT), 272; and homozygous mutant (TT), 63 patients, respectively] and showed no difference in the patient subgroups with various renal diseases. The MTHFR C677T gene polymorphism significantly influenced total homocysteine and folate plasma concentrations in renal transplant recipients (P = 0.0009 and P = 0.0002, respectively). Furthermore, a significant influence of the GFR (P = 0.0001), folate levels (P = 0.0001), age (P = 0.0001), body mass index (P = 0.0001), gender (P = 0.0005), and vitamin B12 levels (P = 0.004) on total homocysteine concentrations was observed. The donor MTHFR gene polymorphism had no influence on total homocysteine and folate levels. Geometric mean total homocysteine levels in patients homozygous for the mutant MTHFR allele were 18.6 micromol/liter compared with 14.6 micromol/liter and 14.9 micromol/liter in patients heterozygous for the MTHFR gene polymorphism and those with wild-type alleles (P < 0.05 for TT vs. CT and CC). Geometric mean folate levels were lower in CT and TT patients (11.2 and 10.2 nmol/liter) compared with CC patients (13.6 nmol/liter, P < 0.05 vs. CT and TT). CONCLUSIONS: This study demonstrates that homozygosity for the C677T polymorphism in the MTHFR gene significantly increases total homocysteine concentrations and lowers folate levels in kidney graft recipients, even in patients with excellent renal function (GFR more than median). These findings have important implications for risk evaluation and vitamin intervention therapy in these patients who carry an increased risk for the development of cardiovascular disease.     

DNA损伤修复基因XRCC1 Arg194Trp基因多态性与中国人群结直肠癌易感性的Meta分析

【摘要】 目的 探讨DNA损伤修复基因XRCC1 Arg194Trp基因多态性与中国人群结直肠癌易感性的关系。方法 按照制定的检索策略,通过计算机和手工检索相关数据库,收集有关XRCC1 Arg194Trp基因多态性与中国人群结直肠癌易感性的病例对照研究,按照纳入标准筛选文献、并从纳入文献中提取相关数据,以病例组和对照组基因型分布的比值比(OR)为效应指标,应用Stata12.0软件进行异质性检验,对各研究原始数据进行Meta合并,并行敏感性分析和发表偏倚的评估。结果〓本Meta分析共纳入11项病例对照研究,累积病例2710例,对照3567例。根据各研究间的异质性,采用不同的模型进行合并效应量。在等位基因比较(T vs C) [OR(95%CI)=1.18(1.01-1.39),P=0.036],纯合子比较模型(TT vs CC) [OR (95%CI)=1.39(1.02-1.90),P=0.038],显性模型(CT/TT vs CC) [OR(95%CI)=2.24(1.78-2.82),P<0.001] 以及隐性模型 (TT vs CT/CC) [OR(95%CI)=1.23(1.02-1.49),P=0.030]均存在显著的统计学差异。发表偏倚评估均未见明显偏倚。结论〓在中国人群中,携带突变等位基因T或突变纯合子TT的人群罹患CRC的风险有所升高,而在显性遗传模型中,携带有CT/TT基因型的人群其CRC的易感性明显升高。     

男性FASL-844基因多态性与特发性无精子症及严重少精子症发病风险的研究

目的:研究FASL-844位点基因多态性在中国南方汉族男性人群中的分布,探讨其与特发性无精子症及严重少精子症发病风险的关系。方法:采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)方法,分析184例特发性无精子症及严重少精子症患者与236例正常生育男性FASL-844位点的基因型及等位基因频率,分析该基因多态性与特发性无精子症及严重少精子症之间的关系。结果:不育组与正常生育组FASL-844CT和TT基因型分布差异有显著性(P=0.024;P=0.008)。携带FASL-844TT基因型个体罹患特发性无精子症或严重少精子症的风险是CC基因型个体的2.76倍(95%CI:1.20~6.35);将携带CC和CT基因型的个体合并,携带TT基因型的个体罹患特发性无精子症或严重少精子症的风险是(CC+CT)基因型个体的2.90倍(95%CI:1.28~6.58)。结论:FASL-844基因多态性可能是中国南方汉族男性特发性无精子症及严重少精子症的遗传易感因素之一。     

Polymorphism in methylenetetrahydrofolate reductase gene: its impact on plasma homocysteine levels and carotid atherosclerosis in ESRD patients receiving hemodialysis

The methylenetetrahydrofolate reductase (MTHFR) gene polymorphism has been shown to be associated with cardiovascular disease in healthy subjects as well as in patients with end-stage renal disease (ESRD). In this study, we examined the allelic frequency and genotype distribution of the MTHFR gene in 151 Chinese ESRD patients receiving hemodialysis and 135 healthy controls. In addition, we investigated the relationship between the MTHFR gene polymorphism and the plasma homocysteine (Hcy) level as well as the intima-media thickness of common carotid artery (CC-IMT) in these patients. The allelic frequency of the MTHFR gene with the C677T mutation in ESRD patients was 24.5% and that in healthy controls was 23%. Mean plasma Hcy level of the ESRD patients (23.1 +/- 7.4 micromol/l) was significantly higher than that of the controls (10.1 +/- 5.0 micromol/l), but did not correlate with vitamin B(6) and vitamin B(12) status. Moreover, the extent of hyperhomocysteinemia was genetically affected by the C677T mutation of the MTHFR gene. The plasma Hcy levels for the patients with the CC, CT and TT genotypes of the MTHFR gene were 22.3 +/- 6.8, 22.8 +/- 7.3, and 28.3 +/- 2.8 micromol/l, respectively. In addition, we found that the patients bearing the TT genotype had the highest CC-IMT (0.93 +/- 0.07 mm), whereas the lowest values (0.79 +/- 0.13 mm) were observed in those who had the CC genotype. One-way ANOVA showed that the CC-IMT in the patients with the TT genotype was significantly greater than that of the patients with the CC genotype (p < 0.05). Moreover, the mean CC-IMT of the patients carrying either TT or CT genotype of the MTHFR gene was significantly higher than that of the patients bearing the CC genotype (0.86 +/- 0.14 vs. 0.79 +/- 0.13 mm, p = 0.002). Multiple regression analysis, in which the change in CC-IMT was used as the dependent variables, identified age, smoking, the MTHFR genotype (CC = 0, CT = 1, TT = 2) and diabetes mellitus as the independent variables significantly associated with the increase of CC-IMT (p < 0.001). These risk factors jointly explained 43.9% of the CC-IMT variation and age explained most of the variation (R(2) = 0.34). We conclude that both the TT genotype and the T allele of the MTHFR gene are associated with the increase of CC-IMT in hemodialysis patients. The C677T mutation of the MTHFR gene may be an independent risk factor that predicts the development of carotid atherosclerosis in ESRD patients.     

精子Tektin-2基因单核苷酸多态性与特发性弱精子症的相关性研究

目的探讨Tektin-2基因的单核苷酸多态性(SNP)位点rs12043423与特发性弱精子症的相关性。方法采用病例对照法,随机选取特发性弱精子症患者192例作为弱精子症组,另募集同期208例精子活力正常的不育男性作为不育症组和213例精液正常的已生育男性作为正常对照组,所有研究对象均进行精液分析,对三组患者Tektin-2基因的SNP位点rs12043423进行基因分型,比较三组间的基因型和等位基因频率,并且进行与特发性弱精子症的关联分析。结果(1)弱精子症组Tektin-2基因的SNP位点rs12043423的CC基因型频率显著低于正常对照组及不育症组,TT基因型频率则显著增加(P<0.05),而CT基因型频率在三组间的分布频率无显著性差异(P>0.05)。弱精子症组C等位基因的分布频率显著低于正常对照组和不育症组,而T等位基因的频率显著高于正常对照组和不育症组(P<0.05)。不育症组和正常对照组比较,不同基因型的分布频率及等位基因的频率在两组间均无显著性差异(P>0.05)。(2)弱精子症组与正常对照组比较,Tektin-2基因突变(杂合子[CT]和纯合子[TT])的发生率为61.5%vs.50.2%,TT基因型与弱精子症的风险因素分析结果为[OR=1.968,95%CI(1.041,3.723),P=0.035];弱精子症与不育症组比较,Tektin-2基因突变(CT+TT)的发生率为61.5%vs.51.5%,TT基因型与弱精子症的风险因素分析结果为[OR=1.918,95%CI(1.014,3.630),P=0.043]。结论Tektin-2基因rs12043423的多态性位点TT基因型和T等位基因增加特发性弱精子症的易感性,在特发性弱精子症的发展中可能是危险因素。