|Ahead of print publication
Association of MTHFR 677C>T polymorphism with breast cancer risk: A case–control study and meta-analysis
Harmesh Lal1, Bhavna Sharma1, Vasudha Sambyal1, Kamlesh Guleria1, Neeti Rajan Singh2, Manjit Singh Uppal2, Mridu Manjari3, Meena Sudan4
1 Department of Human Genetics, Human Cytogenetics Laboratory, Guru Nanak Dev University, Amritsar, Punjab, India
2 Department of Surgery, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
3 Department of Pathology, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
4 Department of Radiotherapy, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
|Date of Submission||28-Jul-2020|
|Date of Decision||15-Sep-2020|
|Date of Acceptance||25-Dec-2020|
|Date of Web Publication||23-Oct-2021|
Department of Human Genetics, Human Cytogenetics Laboratory, Guru Nanak Dev University, Amritsar, Punjab
Source of Support: None, Conflict of Interest: None
Background and Objectives: Breast cancer is a complex, multifactorial disease that arises as a result of interactions between multiple genes and environmental factors. Methylenetetrahydrofolate reductase (MTHFR) is a low susceptibility gene, involved in folate metabolism. It assists in conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate which further leads to DNA methylation. 5,10-methylenetetrahydrofolate assists in conversion of uracil to thymine and purine synthesis for DNA synthesis. MTHFR 677C>T polymorphism alters the activity of MTHFR enzyme potentially effecting DNA repair and synthesis, hence a potential risk for cancer like breast cancer. Hence, the present study was conducted to evaluate association of MTHFR 677C>T polymorphism and breast cancer in Punjabi population. Moreover, a meta-analysis was conducted to address the same.
Materials and Methods: A total of 247 breast cancer patients and 247 controls were selected from Punjabi population for analysis using PCR-RFLP method. For meta-analysis, 67 studies were selected, and allele contrast, homozygous, heterozygous, dominant, and recessive models were used to evaluate the association between MTHFR 677C>T and breast cancer.
Results: The frequencies of CC, CT, and TT genotype were 68.4% versus 74.5%, 28.7% versus 23.5%, and 2.9% versus 2.0% in patients and controls, respectively. There was no significant difference found. In meta-analysis, significant association was found in overall and Asian population while no significant association was found in Caucasians.
Interpretation and Conclusions: MTHFR 677C>T polymorphism is not a risk factor for breast cancer in Punjabi population. Inconsistency with the meta-analysis can be due to ethnic diversity.
Keywords: Breast cancer, meta-analysis, methylenetetrahydrofolate reductase, polymorphism
|How to cite this URL:|
Lal H, Sharma B, Sambyal V, Guleria K, Singh NR, Uppal MS, Manjari M, Sudan M. Association of MTHFR 677C>T polymorphism with breast cancer risk: A case–control study and meta-analysis. J Can Res Ther [Epub ahead of print] [cited 2022 Jun 25]. Available from: https://www.cancerjournal.net/preprintarticle.asp?id=329051
| > Introduction|| |
Breast cancer, with a worldwide incidence rate of 2.1 million in 2018, is the most frequent cancer and the leading cause of cancer death among women. It is also the leading cause of disability-adjusted life years among women worldwide.
Breast cancer is a complex and multifactorial disease that arises as a result of interaction between environmental and genetic risk factors and is highly heterogeneous in nature., Age at menarche and menopause, reproduction history, high level of estrogen, age, body mass index (BMI), alcohol consumption, cigarette smoking, ionizing radiation exposure, family history of the disease, and genetic background are risk factors of this cancer.
Low susceptibility genes in interaction with environmental factors are the important cause of the development of cancer. Methylenetetrahydrofolate reductase (MTHFR) is a low susceptibility gene mapped to chromosome 1p36.3 which encodes MTHFR enzyme involved in the folate metabolism pathway. It leads to irreversible conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate which is the primary form of circulatory folate. 5-methyltetrahydrofolate is involved in remethylation of homocysteine to methionine. Methionine is a precursor for the synthesis of “S-adenosylmethionine” which is involved in the methylation of DNA. 5,10-methylenetetrahydrofolate is involved in purine synthesis and conversion of uracil to thymine for DNA synthesis. Folate is required for DNA methylation, DNA synthesis, and repair; therefore, its deficiency has been related to the development of various cancers, including breast cancer.
Polymorphisms in the genes involved in folate metabolism pathway have potential to influence the pathway. MTHFR 677C>T polymorphism is a polymorphism that causes substitution of alanine to valine at 222 amino acid position that leads to thermolabile enzyme with reduced activity. Homozygous mutant (TT) has 30% activity while heterozygous (CT) has 65% activity compared to wild-type homozygous. As this polymorphism can affect DNA repair and synthesis, hence, it is a potential candidate for cancer risk. There are several published studies that have investigated the association between MTHFR 677C>T polymorphism and breast cancer susceptibility but have given contradictory results.
In India, breast cancer is the most frequent and leading cause of cancer death among women. The total number of new breast cancer cases diagnosed in India comprises 15.46% of all cancer cases in both sexes and 27.7% of all cancer cases in females. In Punjab, in North India, increased incidence of cancer has been reported and the age-adjusted rate of breast cancer incidence ranges from 17.3 to 37.3 per 100,000. Besides this, Punjabi women have been reported to be anemic which can be due to folate deficiency. Therefore, this case–control study was carried to investigate the association between MTHFR 677C >T and breast cancer susceptibility in Punjab region.
In previous studies from India, four studies showed significant association of T allele with increased breast cancer,,,, one showed significant association of the minor “T” allele with decreased breast cancer, three studies showed nonsignificant association.,, There is no published study yet which investigates the association of MTHFR 677C>T with breast cancer from Punjab. Meta-analysis, being a robust tool to examine inconsistencies in the results due to multiple factors, was conducted in all eligible studies to address the same.
| > Materials and Methods|| |
The present study involved 247 confirmed breast cancer patients diagnosed at tertiary care hospital and 247 age-, gender-, and habitat-matched volunteers as control for analysis. Control group consists of unrelated healthy individuals with no family history of any cancer in at least three generations and no history of any other chronic disease. All subjects were from Punjabi population. Predesigned questionnaire was used to collect information regarding personal history, family history, disease history, etc., Informed consent was obtained from all the participants, and the study was carried out under the guidelines of institutional ethical committee, as per the Declaration of Helsinki.
Analysis of MTHFR 677C>T polymorphism
Five milliliters of venous blood from each subject was collected in 0.5 M EDTA vial and stored at − 20°C until further analysis. DNA was extracted from blood by standard phenol-chloroform method. Analysis of polymorphism was done by PCR-RFLP method. Amplification of genomic DNA sequence was achieved by specific set of primers which generate 203 bp long PCR product. The PCR products were digested with Hinf I (NEB) restriction digestion enzyme. C to T substitution created a site for Hinf I enzyme which produced 173 bp and 30 bp long fragments on digestion [Figure 1].
|Figure 1: Photograph of 2% EtBr stained agarose gel electrophoresis showing HinfI digested products. (lane 1, 4, 5 = CC; lane 2 = TT; lane 3, 6 = CT; M = 100 bp molecular marker)|
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Genotypic and allelic frequencies were calculated, and Chi-square goodness-of-fit test was used to test whether the distribution of control sample was in accordance with the Hardy–Weinberg equilibrium (HWE). Odds ratio of allelic and genotypic distribution along with 95% of confidence interval was used to assess the association between polymorphism and breast cancer risk. Comparison of genotypic data of cases and controls was done by Chi-square test. P < 0.05 was considered statistically significant.
Eligible studies analyzing the association between MTHFR 677C>T and breast cancer were retrieved by searching PubMed, Google Scholar, Scopus, and Web of Science databases. The keywords used for retrieval were “breast cancer,” “breast carcinoma,” “breast neoplasms” in combination with “MTHFR,” “methylenetetrahydrofolatereductase,” “C677T,” “Ala222Val,” “rs1801133.” The references of retrieved studies were also searched to identify relevant studies.
Inclusion and exclusion criteria
The inclusion criteria for eligible studies were as follows: (1) case–control studies published in peer-reviewed journal, (2) investigating the association of MTHFR C677T polymorphism with breast cancer, (3) genotype data of cases and controls were complete, (4) genotype distribution of control must comply with the HWE, and (5) studies published only in English. The exclusion criteria were as follows: (1) studies with overlapped data, (2) no detailed information of genotype data, (3) meta-analysis and reviews, and (4) genotypic data not in HWE.
First author's name, year of publication, country, ethnicity, sample size, and genotypic and allelic frequencies were extracted from each study. Different ethnicities were categorized as Asians, Caucasians, and Africans. Studies with multiple ethnicities were categorized as mixed.
Chi-square test between observed and expected genotypic distribution was used to check the Hardy–Weinberg distribution in control samples only. Odds ratios with 95% confidence interval were used to evaluate association between MTHFR 677C>T and breast cancer risk. P ≤ 0.05 was considered statistically significant. Five genetic models: homozygote model (TT vs. CC), heterozygote model (CT vs. CC), dominant model (CT + TT vs. CC), recessive model (TT vs. CT + CC), and allele model (T vs. C) were used to evaluate association between MTHFR 677C>T polymorphism and breast cancer in overall and subgroup analysis. Subgroup analysis was conducted on the basis of ethnicity and source of controls. Cochran's Chi-square–based Q-statistic was used to assess the heterogeneity among studies, and quantification of heterogeneity was assessed by I2 test (I2 ranges from 0% to 100%, with higher value representing the higher heterogeneity). Random effect model was used, to incorporate the between studies' heterogeneity in calculation, if P < 0.05 or I2 >50%; otherwise, fixed effect model was used for meta-analysis., Estimation of potential publication bias was carried out by funnel plot, Begg's, and Egger's test., The Package “Meta: An R package of meta-analysis” in R Studio version 1.1.463, RStudio PBC, 250 Northern Ave, Boston, MA 02210, USA was used to conduct meta-analysis of all related studies.
| > Results|| |
In case–control study, 247 breast cancer patients (243 females, 4 males) and 247 age-, gender-, and habitat-matched healthy controls were screened. 60 (24.3%) subjects belonged to urban area and 184 (74.5%) belonged to rural area while 3 (1.2%) subjects were from suburban area in both cases and controls. Mean age (in years) of the cases and controls was 46.79 ± 11.54 and 46.39 ± 13.23, respectively. For cases and controls, the mean BMI (kg/m2) was 25.71 ± 5.33 and 26.41 ± 4.57 while the mean Waist Hip Ratio (WHR) was 0.96 ± 0.07 and 0.96 ± 0.06, respectively. In cases, 139 subjects were vegetarian and 104 were nonvegetarian, while in controls, 142 subjects were vegetarian and 101 were nonvegetarian. There was no significant difference in age, BMI, WHR, and diet between cases and controls.
The genotypic and allelic frequencies of cases and controls are presented in [Table 1]. Distribution of genotypic frequency in controls was in accordance with HWE (P = 0.86). The frequency of CC genotype was lower in cases (68.4%) as compared to controls (74.5%). The CT and TT genotypes were higher in cases than that in the controls, but difference was statistically nonsignificant.
|Table 1: Distribution of MTHFR 677C>T allelic and genotypic frequencies among breast cancer cases and controls|
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Following the inclusion and exclusion criteria, 67 case–control studies including the present study were included in this meta-analysis [Supplementary Table 1].,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, At first, 119 studies, without including the present study, were selected by searching different databases. Out of these studies, 24 studies were excluded because these were not case–control studies, 7 studies were excluded due to incomplete data, 12 studies were not in HWE, 4 studies reported duplicated data, 1 study was retracted, 2 studies was removed due to publication bias, and 2 studies were removed because they reported ambiguous data. The total number of cases and controls included in this meta-analysis was 23,440 and 27,880, respectively. Of these 67 studies, 27 were carried out among Asian, 29 were Caucasian, and 11 were among mixed population. In 28 studies, controls were recruited from general population, 29 studies were hospital-based studies, while there were no data on source of controls in 10 studies.
Pooled data showed a moderately significant heterogeneity in all models. Meta-analysis in four genetic models, i.e., allele contrast, homozygote, dominant and recessive model, showed a mild but significant association of MTHFR 677C>T polymorphism with breast cancer risk. Forest plot has been drawn for the allele contrast model to estimate the association of MTHFR 677C>T polymorphism with the risk of breast cancer [Figure 2]. In cumulative meta-analysis with random effects model, the association of T allele with breast cancer risk became significant with addition of Gao et al.'s study and remained significant after this. [Table 2] summarizes the results for pooled analysis.
|Table 2: Summary for odds ratio with 95% confidence interval, P value for heterogeneity, I2, and P values for Begg's and Egger's test for publication bias in different genetic models|
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In Asians, significant association was found between increased breast cancer risk and MTHFR 677C>T polymorphism in all models, except in heterozygote and dominant models. In Caucasians, association was found to be nonsignificant. A significant heterogeneity was found in Asians subgroup. On stratification by the source of control group, population-based studies showed significant heterogeneity in allele contrast model, homozygote model, and recessive model. Association between MTHFR 677C>T polymorphism and breast cancer risk was nonsignificant in recessive model with random effects; otherwise, the association was found to be significant in all other model. In hospital-based studies, significant association was found in homozygote and recessive model. Hospital-based studies showed comparatively more heterogeneity than population-based studies.
In studies comprising Indian population, significant high heterogeneity between studies was found in allele contrast, heterozygote, and dominant model. Homozygote and recessive models showed lack of heterogeneity and high risk of breast cancer was found in these models although the association was still statistically nonsignificant. [Table 3] summarizes the results of subgroup analysis.
|Table 3: Summary for odds ratios with 95% confidence interval, P value for heterogeneity, and I2 value in subgroup analysis|
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Publication bias and sensitivity analysis
Funnel plot [Figure 3], Begg's, and Egger's tests were used to carry out the estimation of publication bias in all genetic model. Sensitivity analysis was performed to analyze the stability of result by omitting one study at a time and excluding the studies with less than 100 subjects in one of the groups. No change was materially observed, indicating the stability of result.
| > Discussion|| |
Folate metabolism pathway is involved in the biosynthesis of purines, thymidylates for repair, and synthesis of DNA. Hence, folate deficiency can compromise nucleotide synthesis and lead to uracil misincorporation and chromosome breakage. Folate metabolism pathway is also involved in the synthesis of S-adenosylmethionine, the universal methyl donor for DNA methylation. Compromising the synthesis of S-adenosylmethionine can lead to hypomethylation, potentially influence the gene expression, and facilitate carcinogenesis., Generally, folate prevents the development of tumors before established preneoplastic lesions, but it would improve tumorigenesis after the establishment of lesions.
MTHFR is a low susceptibility gene in the folate metabolism pathway, and MTHFR 677C>T polymorphism is a common polymorphism which leads to thermolabile enzyme with reduced activity. Therefore, this polymorphism has potential to influence the pathway, hence various cancers including breast cancer. Previously, many studies were conducted to evaluate the association between MTHFR 677C>T polymorphism and breast cancer in the past, but the results were inconclusive. For instance, CT genotype was found to be associated with 1.5-fold increase in breast cancer risk in population from England, but European multicenter study reported nonsignificant association. Similarly, for TT genotype, Ergul et al. reported correlation with increased breast cancer risk, but Cam et al. reported no association with risk in Turkish population.
Furthermore, association of this polymorphism with breast cancer can be modified by folate intake and other nutrients intake., As women in Punjab have been reported to be anemic which can be because of folate deficiency, 247 cases and 247 controls from the Punjab region were analyzed for MTHFR 677C>T polymorphism in the present study, and we found no significant association of MTHFR 677C>T polymorphism with breast cancer risk. In previous studies from the Indian population, two studies reported nonsignificant association of polymorphism with breast cancer., Another study from South India reported higher frequencies of CT genotype and T allele in controls than cases but nonsignificant association. Hence, the present study is in agreement with these previous studies.
On the other side, CT genotype and T allele have been reported to be associated with increased breast cancer risk from Uttar Pradesh and Jammu and Kashmir region, in North India., In another study, TT genotype was found to be associated with increased breast cancer risk in the South Indian population. The authors suggest that relation with high risk could be due to thermolabile enzyme which has tendency to lose its active dimer form with loss in the FAD-binding capacity and decreased specific activity. In another study from Jammu and Kashmir, T allele reported to be associated with protection, although the sample size for study was small.
Inconsistency in the results of the different studies can be due to different lifestyle, dietary pattern, source of subjects, environmental factors, and ethnicity. Meta-analysis is a robust tool to examine these inconsistencies. Several meta-analyses have been published for the purpose of investigating the role of MTHFR 677C>T polymorphism and breast cancer risk whose details are given in [Supplementary Table 2].
First meta-analysis was published in 2006 which showed no association of MTHFR 677C>T polymorphism with breast cancer risk. Similar results were observed in two other meta-analyses., In a meta-analysis comprises 39 studies, T allele and TT genotype were significantly correlated with increased breast cancer risk, but here some studies were missing from analysis. Besides this, meta-analysis included an overlapped study. Zhang et al., Qi et al., Yu and Chen, Li et al., Zhong et al., and Yan et al. pooled 37, 41, 51, 57, 59, and 23 studies, respectively, and suggested a significant correlation of TT genotype with increased breast cancer susceptibility.,,,,, Kumar et al. in their meta-analysis of 75 studies also reported the increased breast cancer risk associated with T allele and TT genotype in overall population. Xie et al., Gonzales et al., Zhang et al., and Mo et al. pooled 68, 83, 82, and 85 studies, respectively, and suggested a significant association of MTHFR 677C>T with breast cancer risk.,,, However, these meta-analyses involved many studies that deviated from HWE.
Liang et al. suggested association of T allele and TT genotype with increased breast cancer susceptibility in the Chinese population; however, this meta-analysis based on 22 studies had multiple issues which were further resolved by another meta-analysis, although the results remained the same. On the other hand, significant protection was found in Chinese Han population with high significant heterogeneity in dominant model. T allele and TT genotype were also associated with increased breast cancer risk in Turkish and Latino population., On the other hand, pooled analysis of 61 studies reported nonsignificant association of MTHFR 677C>T polymorphism with breast cancer susceptibility which was contradictory to previous meta-analyses.
Present meta-analysis pooling 67 studies, excluded the studies which deviated from HWE for the purpose of stringent inclusion criteria, were undertaken which indicated the significant association of MTHFR 677C>T polymorphism with breast cancer susceptibility. In subgroup analysis, MTHFR 677C>T was found to be significantly associated with breast cancer risk in Asians. In another published meta-analysis, T allele and TT genotype were found to be associated with the mild increase in breast cancer risk in Asians and authors suggested that MTHFR 677C>T polymorphism contributes to overall risk of breast cancer. Compared to the present meta-analysis, previously published meta-analyses either had included fewer studies or studies which deviated from HWE. As Asian studies showed significant between studies' heterogeneity and mainly consist of studies on the Chinese population, a pooled analysis based on studies on the Indian population was conducted. In this analysis, the association was found to be nonsignificant which was in agreement with the present case–control study.
As inconsistency can arise due to the source of controls, subgroup analysis based on the source of control was conducted to achieve more accurate results. The present study suggests that hospital-based studies contribute more heterogeneity than population-based studies. Furthermore, sensitivity analysis of excluding studies with less than 100 subjects in either of the group and excluding one study at a time to identify the study affecting the results had been performed to increase the robustness of the results.
The present meta-analysis is the updated meta-analysis till the date which investigates the association of MTHFR 677C>T polymorphism with breast cancer risk. However, present meta-analysis and case–control study had some limitations: (1) gene–gene and gene–environment interaction had not been analyzed; (2) only single polymorphism of a gene is considered. Furthermore, other limitation for meta-analysis was that only studies published in English were included.
| > Conclusions|| |
The present case–control study suggested that MTHFR 677C>T polymorphism was not associated with breast cancer risk in the population of Punjab region. Although present meta-analysis indicated a positive correlation of polymorphism with breast cancer risk, it showed significant between studies' heterogeneity which indicated that association may differ between different populations.
We are highly thankful to all the subjects for their valuable participation. Financial assistance from UGC under UPE and CPEPA scheme sanctioned to Dr. Vasudha Sambyal and Dr. Kamlesh Guleria and DST-FIST, PURSE grant, and CSIR-SRF to Harmesh Lal is highly acknowledged.
Financial support and sponsorship
Financial assistant from UGC under UPE and CPEPA scheme, DST-FIST, PURSE grant, and CSIR supported the study.
Conflicts of interest
There are no conflicts of interest.
| > References|| |
Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 2018;68:394-424.
Global Burden of Disease Cancer Collaboration, Fitzmaurice C, Akinyemiju TF, Al Lami FH, Alam T, Alizadeh-Navaei R, et al
. Global, regional, and national cancer incidence, mortality, years of life lost, years lived with disability, and disability-adjusted life-years for 29 cancer groups, 1990 to 2016: A systematic analysis for the global burden of disease study. JAMA Oncol 2018;4:1553-68.
Ponder BA. Cancer genetics. Nature 2001;411:336-41.
Verma R, Bowen RL, Slater SE, Mihaimeed F, Jones JL. Pathological and epidemiological factors associated with advanced stage at diagnosis of breast cancer. Br Med Bull 2012;103:129-45.
Hankinson SE, Colditz GA, Willett WC. Towards an integrated model for breast cancer etiology: The lifelong interplay of genes, lifestyle, and hormones. Breast Cancer Res 2004;6:213-8.
Lichtenstein P, Holm NV, Verkasalo PK, Iliadou A, Kaprio J, Koskenvuo M, et al
. Environmental and heritable factors in the causation of cancer--Analyses of cohorts of twins from Sweden, Denmark, and Finland. N Engl J Med 2000;343:78-85.
Goyette P, Sumner JS, Milos R, Duncan AM, Rosenblatt DS, Matthews RG, et al
. Human methylenetetrahydrofolate reductase: Isolation of cDNA, mapping and mutation identification. Nat Genet 1994;7:195-200.
Frosst P, Blom HJ, Milos R, Goyette P, Sheppard CA, Matthews RG, et al
. A candidate genetic risk factor for vascular disease: A common mutation in methylenetetrahydrofolate reductase. Nat Genet 1995;10:111-3.
Matthews RG, Sheppard C, Goulding C. Methylenetetrahydrofolate reductase and methionine synthase: Biochemistry and molecular biology. Eur J Pediatr 1998;157 Suppl 2:S54-9.
Bailey LB, Gregory JF 3rd
. Folate metabolism and requirements. J Nutr 1999;129:779-82.
Kim YI. Folate and carcinogenesis: Evidence, mechanisms, and implications. J Nutr Biochem 1999;10:66-88.
Labani S, Asthana S, Sultan A. Cancer in Punjab: Evidence from cancer atlas. Indian J Community Health 2015;27:295-7.
Bhatia, M. Hunger and under-nutrition in green revolutionary state of Punjab. Int J Agri Food Sci Technol 2013;4:359-70.
Naushad SM, Pavani A, Digumarti RR, Gottumukkala SR, Kutala VK. Epistatic interactions between loci of one-carbon metabolism modulate susceptibility to breast cancer. Mol Biol Rep 2011;38:4893-901.
Mohammad NS, Yedluri R, Addepalli P, Gottumukkala SR, Digumarti RR, Kutala VK. Aberrations in one-carbon metabolism induce oxidative DNA damage in sporadic breast cancer. Mol Cell Biochem 2011;349:159-67.
Waseem M, Hussain SR, Kumar S, Serajuddin M, Mahdi F, Sonkar SK, et al
. Association of MTHFR
(C677T) gene polymorphism with breast cancer in North India. Biomark Cancer 2016;8:111-7.
Sharma R, Raina JK, Azad T, Kumar P, Panjaliya RK. Methylenetetrahydrofolate reductase (MTHFR) and angiotensin converting enzyme (ACE) gene variations in link with breast cancer in Jammu Region of Jammu and Kashmir state. Int J Hum Genet 2018;18:219-27.
Mir MM, Dar JA, Dar NA, Dar MS, Salam I, Lone MM, et al
. Combined impact of polymorphism of folate metabolism genes; glutamate carboxypeptidase, methylene tetrahydrofolate reductase and methionine synthase reductase on breast cancer susceptibility in kashmiri women. Int J Health Sci (Qassim) 2008;2:3-14.
Kalyankumar C, Jamil K. Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphism and breast cancer in South Indian Population. Int J Cancer Res 2006;2:143-51.
Prasad VV, Wilkhoo H. Association of the functional polymorphism C677T in the methylenetetrahydrofolate reductase gene with colorectal, thyroid, breast, ovarian, and cervical cancers. Onkologie 2011;34:422-6.
Pooja S, Carlus J, Sekhar D, Francis A, Gupta N, Konwar R, et al
. MTHFR 677C>T polymorphism and the risk of breast cancer: Evidence from an original study and pooled data for 28031 cases and 31880 controls. PLoS One 2015;10:e0120654.
Adeli K, Ogbonna G. Rapid purification of human DNA from whole blood for potential application in clinical chemistry laboratories. Clin Chem 1990;36:261-4.
Toffoli G, Russo A, Innocenti F, Corona G, Tumolo S, Sartor F, et al
. Effect of methylenetetrahydrofolate reductase 677C>T polymorphism on toxicity and homocysteine plasma level after chronic methotrexate treatment of ovarian cancer patients. Int J Cancer 2003;103:294-9.
DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials 1986;7:177-88.
Mantel N, Haenszel W. Statistical aspects of the analysis of data from retrospective studies of disease. J Natl Cancer Inst 1959;22:719-48.
Begg CB, Mazumdar M. Operating characteristics of a rank correlation test for publication bias. Biometrics 1994;50:1088-101.
Egger M, Davey Smith G, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ 1997;315:629-34.
Sharp L, Little J, Schofield AC, Pavlidou E, Cotton SC, Miedzybrodzka Z, et al
. Folate and breast cancer: The role of polymorphisms in methylenetetrahydrofolate reductase (MTHFR). Cancer Lett 2002;181:65-71.
Campbell IG, Baxter SW, Eccles DM, Choong DY. Methylenetetrahydrofolate reductase polymorphism and susceptibility to breast cancer. Breast Cancer Res 2002;4:R14.
Ergul E, Sazci A, Utkan Z, Canturk NZ. Polymorphisms in the MTHFR gene are associated with breast cancer. Tumour Biol 2003;24:286-90.
Semenza JC, Delfino RJ, Ziogas A, Anton-Culver H. Breast cancer risk and methylenetetrahydrofolate reductase polymorphism. Breast Cancer Res Treat 2003;77:217-23.
Langsenlehner U, Krippl P, Renner W, Yazdani-Biuki B, Wolf G, Wascher TC, et al
. The common 677C>T gene polymorphism of methylenetetrahydrofolate reductase gene is not associated with breast cancer risk. Breast Cancer Res Treat 2003;81:169-72.
Grieu F, Powell B, Beilby J, Iacopetta B. Methylenetetrahydrofolate reductase and thymidylate synthase polymorphisms are not associated with breast cancer risk or phenotype. Anticancer Res 2004;24:3215-9.
Försti A, Angelini S, Festa F, Sanyal S, Zhang Z, Grzybowska E, et al
. Single nucleotide polymorphisms in breast cancer. Oncol Rep 2004;11:917-22.
Lee SA, Kang D, Nishio H, Lee MJ, Kim DH, Han W, et al
. Methylenetetrahydrofolate reductase polymorphism, diet, and breast cancer in Korean women. Exp Mol Med 2004;36:116-21.
Lin WY, Chou YC, Wu MH, Huang HB, Jeng YL, Wu CC, et al
. The MTHFR C677T polymorphism, estrogen exposure and breast cancer risk: A nested case-control study in Taiwan. Anticancer Res 2004;24:3863-8.
Shrubsole MJ, Gao YT, Cai Q, Shu XO, Dai Q, Hébert JR, et al
. MTHFR polymorphisms, dietary folate intake, and breast cancer risk: Results from the Shanghai Breast Cancer Study. Cancer Epidemiol Biomarkers Prev 2004;13:190-6.
Justenhoven C, Hamann U, Pierl CB, Rabstein S, Pesch B, Harth V, et al
. One-carbon metabolism and breast cancer risk: No association of MTHFR, MTR, and TYMS polymorphisms in the GENICA study from Germany. Cancer Epidemiol Biomarkers Prev 2005;14:3015-8.
Kalemi TG, Lambropoulos AF, Gueorguiev M, Chrisafi S, Papazisis KT, Kotsis A. The association of p53 mutations and p53 codon 72, Her 2 codon 655 and MTHFR C677T polymorphisms with breast cancer in Northern Greece. Cancer Lett 2005;222:57-65.
Deligezer U, Akisik EE, Dalay N. Homozygosity at the C677T of the MTHFR gene is associated with increased breast cancer risk in the Turkish population. In Vivo
Chen J, Gammon MD, Chan W, Palomeque C, Wetmur JG, Kabat GC, et al
. One-carbon metabolism, MTHFR polymorphisms, and risk of breast cancer. Cancer Res 2005;65:1606-14.
Chou YC, Wu MH, Yu JC, Lee MS, Yang T, Shih HL, et al
. Genetic polymorphisms of the methylenetetrahydrofolate reductase gene, plasma folate levels and breast cancer susceptibility: A case-control study in Taiwan. Carcinogenesis 2006;27:2295-300.
Reljic A, Simundic AM, Topic E, Nikolac N, Justinic D, Stefanovic M. The methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and cancer risk: The Croatian case-control study. Clin Biochem 2007;40:981-5.
Hekim N, Ergen A, Yaylim I, Yilmaz H, Zeybek U, Oztürk O, et al
. No association between methylenetetrahydrofolate reductase C677T polymorphism and breast cancer. Cell Biochem Funct 2007;25:115-7.
Macis D, Maisonneuve P, Johansson H, Bonanni B, Botteri E, Iodice S, et al
. Methylenetetrahydrofolate reductase (MTHFR) and breast cancer risk: A nested-case-control study and a pooled meta-analysis. Breast Cancer Res Treat 2007;106:263-71.
Yu CP, Wu MH, Chou YC, Yang T, You SL, Chen CJ, et al
. Breast cancer risk associated with multigenotypic polymorphisms in folate-metabolizing genes: A nested case-control study in Taiwan. Anticancer Res 2007;27:1727-32.
Kotsopoulos J, Zhang WW, Zhang S, McCready D, Trudeau M, Zhang P, et al
. Polymorphisms in folate metabolizing enzymes and transport proteins and the risk of breast cancer. Breast Cancer Res Treat 2008;112:585-93.
Cheng CW, Yu JC, Huang CS, Shieh JC, Fu YP, Wang HW, et al
. Polymorphism of cytosolic serine hydroxymethyltransferase, estrogen and breast cancer risk among Chinese women in Taiwan. Breast Cancer Res Treat 2008;111:145-55.
Inoue M, Robien K, Wang R, Van Den Berg DJ, Koh WP, Yu MC. Green tea intake, MTHFR/TYMS genotype and breast cancer risk: The Singapore Chinese Health Study. Carcinogenesis 2008;29:1967-72.
Suzuki T, Matsuo K, Hirose K, Hiraki A, Kawase T, Watanabe M, et al
. One-carbon metabolism-related gene polymorphisms and risk of breast cancer. Carcinogenesis 2008;29:356-62.
Cam R, Eroglu A, Egin Y, Akar N. Dihydrofolate reductase (DHRF) 19-bp intron-1 deletion and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms in breast cancer. Breast Cancer Res Treat 2009;115:431-2.
Henríquez-Hernández LA, Murias-Rosales A, Hernández González A, Cabrera De León A, Díaz-Chico BN, Mori De Santiago M, et al
. Gene polymorphisms in TYMS, MTHFR, p53 and MDR1 as risk factors for breast cancer: A case-control study. Oncol Rep 2009;22:1425-33.
Platek ME, Shields PG, Marian C, McCann SE, Bonner MR, Nie J, et al
. Alcohol consumption and genetic variation in methylenetetrahydrofolate reductase and 5-methyltetrahydrofolate-homocysteine methyltransferase in relation to breast cancer risk. Cancer Epidemiol Biomarkers Prev 2009;18:2453-9.
Ericson U, Sonestedt E, Ivarsson MI, Gullberg B, Carlson J, Olsson H, et al
. Folate intake, methylenetetrahydrofolate reductase polymorphisms, and breast cancer risk in women from the Malmö Diet and Cancer cohort. Cancer Epidemiol Biomarkers Prev 2009;18:1101-10.
Maruti SS, Ulrich CM, Jupe ER, White E. MTHFR C677T and postmenopausal breast cancer risk by intakes of one-carbon metabolism nutrients: A nested case-control study. Breast Cancer Res 2009;11:R91.
Ma E, Iwasaki M, Junko I, Hamada GS, Nishimoto IN, Carvalho SM, et al
. Dietary intake of folate, vitamin B 6, and vitamin B 12, genetic polymorphism of related enzymes, and risk of breast cancer: A case-control study in Brazilian women. BMC Cancer 2009;9:122.
Ma E, Iwasaki M, Kobayashi M, Kasuga Y, Yokoyama S, Onuma H, et al
. Dietary intake of folate, Vitamin B2, Vitamin B6, Vitamin B12, genetic polymorphism of related enzymes, and risk of breast cancer: A case-control study in Japan. Nutr Cancer 2009;61:447-56.
Jin Z, Lu Q, Ge D, Zong M, Zhu Q. Effect of the methylenetetrahydrofolate reductase gene C677T polymorphism on C-erbB-2 methylation status and its association with cancer. Mol Med Rep 2009;2:283-9.
Gao CM, Tang JH, Cao HX, Ding JH, Wu JZ, Wang J, et al
. MTHFR polymorphisms, dietary folate intake and breast cancer risk in Chinese women. J Hum Genet 2009;54:414-8.
Bentley AR, Raiszadeh F, Stover PJ, Hunter DJ, Hankinson SE, Cassano PA. No association between cSHMT genotypes and the risk of breast cancer in the Nurses' Health Study. Eur J Clin Nutr 2010;64:108-10.
Weiner AS, Boyarskih UA, Voronina EN, Selezneva IA, Sinkina TV, Lazarev AF, et al
. Polymorphic variants of folate metabolizing genes (C677T and A1298C MTHFR and C1420T SHMT1 and G1958A MTHFD) are not associated with the risk of breast cancer in the West Siberian Region of Russia. Mol Biol 2010;44:720-7.
Sangrajrang S, Sato Y, Sakamoto H, Ohnami S, Khuhaprema T, Yoshida T. Genetic polymorphisms in folate and alcohol metabolism and breast cancer risk: A case-control study in Thai women. Breast Cancer Res Treat 2010;123:885-93.
Cerne JZ, Stegel V, Gersak K. Novakovic S. Lack of association between methylenetetrahydrofolate reductase genetic polymorphisms and postmenopausal breast cancer risk. Mol Med Rep 2011;4:175-9.
Batschauer AP, Cruz NG, Oliveira VC, Coelho FF, Santos IR, Alves MT, et al
. HFE, MTHFR, and FGFR4 genes polymorphisms and breast cancer in Brazilian women. Mol Cell Biochem 2011;357:247-53.
Wu XY, Ni J, Xu WJ, Zhou T, Wang X. Interactions between MTHFR C677T-A1298C variants and folic acid deficiency affect breast cancer risk in a Chinese population. Asian Pac J Cancer Prev 2012;13:2199-206.
Akram M, Malik FA, Kayani MA. Mutational analysis of the MTHFR gene in breast cancer patients of Pakistani population. Asian Pac J Cancer Prev 2012;13:1599-603.
Lajin B, Alhaj Sakur A, Ghabreau L, Alachkar A. Association of polymorphisms in one-carbon metabolizing genes with breast cancer risk in Syrian women. Tumour Biol 2012;33:1133-9.
Diakite B, Tazzite A, Hamzi K, Jouhadi H, Nadifi S. Methylenetetrahydrofolate reductase C677T polymorphism and breast cancer risk in Moroccan women. Afr Health Sci 2012;12:204-9.
Carvalho Barbosa Rde C, Menezes DC, Freire TF, Sales DC, Alencar VH, Rabenhorst SH. Associations of polymorphisms of folate cycle enzymes and risk of breast cancer in a Brazilian population are age dependent. Mol Biol Rep 2012;39:4899-907.
Ozen F, Erdis E, Sik E, Silan F, Uludag A, Ozdemir O. Germ-line MTHFR C677T, FV H1299R and PAI-1 5G/4G variations in breast carcinoma. Asian Pac J Cancer Prev 2013;14:2903-8.
Akilzhanova A, Nurkina Z, Momynaliev K, Ramanculov E, Zhumadilov Z, Rakhypbekov T, et al
. Genetic profile and determinants of homocysteine levels in Kazakhstan patients with breast cancer. Anticancer Res 2013;33:4049-59.
Huang CY, Chang WS, Shui HA, Hsieh YH, Loh CH, Wang HC, et al
. Evaluation of the contribution of methylenetetrahydrofolate reductase genotypes to Taiwan breast cancer. Anticancer Res 2014;34:4109-15.
Xi J, Su Y, Beeghly Fadiel A, Lin Y, Su FX, Jia WH, et al
. Association of physical activity and polymorphisms in FGFR2 and DNA methylation related genes with breast cancer risk. Cancer Epidemiol 2014;38:708-14.
Awwad N, Yousef AM, Abuhaliema A, Abdalla I, Yousef M. Relationship between genetic polymorphisms in MTHFR (C677T, A1298C and their haplotypes) and the incidence of breast cancer among Jordanian females--Case-control study. Asian Pac J Cancer Prev 2015;16:5007-11.
Kakkoura MG, Demetriou CA, Loizidou MA, Loucaides G, Neophytou I, Marcou Y, et al
. Single-nucleotide polymorphisms in one-carbon metabolism genes, Mediterranean diet and breast cancer risk: A case-control study in the Greek-Cypriot female population. Genes Nutr 2015;10:453.
Lu Q, Jiang K, Li Q, Ji YJ, Chen WL, Xue XH. Polymorphisms in the MTHFR gene are associated with breast cancer risk and prognosis in a Chinese population. Tumour Biol 2015;36:3757-62.
Zhang XF, Liu T, Li Y. Li S. Association between MTHFR 677C/T and 1298A/C gene polymorphisms and breast cancer risk. Genet Mol Res 2015;14:16425-30.
Ramos-Silva A, Figuera LE, Soto-Quintana OM, Puebla-Pérez AM, Ramírez-Patiño R, Gutiérrez-Hurtado I, et al
. Association of the C677T polymorphism in the methylenetetrahydrofolate reductase gene with breast cancer in a Mexican population. Genet Mol Res 2015;14:4015-26.
Zara-Lopes T, Gimenez-Martins AP, Nascimento-Filho CH, Castanhole-Nunes MM, Galbiatti-Dias AL, Padovani-Júnior JA, et al
. Role of MTHFR C677T and MTR A2756G polymorphisms in thyroid and breast cancer development. Genet Mol Res 2016;15:Gmr8222.
Luo WP, Li B, Lin FY, Yan B, Du YF, Mo XF, et al
. Joint effects of folate intake and one-carbon-metabolizing genetic polymorphisms on breast cancer risk: A case-control study in China. Sci Rep 2016;6:29555.
Kaya EF, Karakus N, Ulusoy AN, Ázaslan C, Kara N. Association of the MTHFR gene C677T polymorphism with breast cancer in a Turkish population. Oncol Res Treat 2016;39:534-8.
Mohammadzadeh G, Karimi M, Bazyar M, Hosseini SM. Lack of association between MTHFR C677T polymorphism and breast cancer risk in Ahvaz, west south-Iran. Adv Biomed Res 2016;5:26.
] [Full text]
Matejcic M, de Batlle J, Ricci C, Biessy C, Perrier F, Huybrechts I, et al
. Biomarkers of folate and Vitamin B12 and breast cancer risk: Report from the EPIC cohort. Int J Cancer 2017;140:1246-59.
Rezende LM, Marson FAL, Lima CSP, Bertuzzo CS. Can MTHFR C677T and A1298C polymorphisms alter the risk and severity of sporadic breast cancer in Brazilian Women? Clin Breast Cancer 2017;17:e199-208.
Hardi H, Melki R, Boughaleb Z, El Harroudi T, Aissaoui S, Boukhatem N. Significant association between ERCC2 and MTHR polymorphisms and breast cancer susceptibility in Moroccan population: Genotype and haplotype analysis in a case-control study. BMC Cancer 2018;18:292.
Houghton SC, Eliassen AH, Zhang SM, Selhub J, Rosner BA, Willett WC, et al
. Plasma B-vitamins and one-carbon metabolites and the risk of breast cancer in younger women. Breast Cancer Res Treat 2019;176:191-203.
Floris M, Sanna D, Castiglia P, Putzu C, Sanna V, Pazzola A, et al
. MTHFR, XRCC1 and OGG1 genetic polymorphisms in breast cancer: A case-control study in a population from North Sardinia. BMC Cancer 2020;20:234.
Blount BC, Mack MM, Wehr CM, MacGregor JT, Hiatt RA, Wang G, et al
. Folate deficiency causes uracil misincorporation into human DNA and chromosome breakage: Implications for cancer and neuronal damage. Proc Natl Acad Sci U S A 1997;94:3290-5.
Balaghi M, Wagner C. DNA methylation in folate deficiency: Use of CpG methylase. Biochem Biophys Res Commun 1993;193:1184-90.
Luczak MW, Jagodziński PP. The role of DNA methylation in cancer development. Folia Histochem Cytobiol 2006;44:143-54.
Kim YI. Does a high folate intake increase the risk of breast cancer? Nutr Rev 2006;64:468-75.
Zintzaras E. Methylenetetrahydrofolate reductase gene and susceptibility to breast cancer: A meta-analysis. Clin Genet 2006;69:327-36.
Lissowska J, Gaudet MM, Brinton LA, Chanock SJ, Peplonska B, Welch R, et al
. Genetic polymorphisms in the one-carbon metabolism pathway and breast cancer risk: A population-based case–control study and meta-analyses. Int J Cancer 2007;120:2696-703.
He L, Shen Y. MTHFR C677T
polymorphism and breast, ovarian cancer risk: A meta-analysis of 19,260 patients and 26,364 controls. Onco Targets Ther 2017;10:227-38.
Zhang J, Qiu LX, Wang ZH, Wu XH, Liu XJ, Wang BY, et al
. MTHFR C677T polymorphism associated with breast cancer susceptibility: A meta-analysis involving 15,260 cases and 20,411 controls. Breast Cancer Res Treat 2010;123:549-55.
Qi X, Ma X, Yang X, Fan L, Zhang Y, Zhang F, et al
. Methylenetetrahydrofolate reductase polymorphisms and breast cancer risk: A meta-analysis from 41 studies with 16,480 cases and 22,388 controls. Breast Cancer Res Treat 2010;123:499-506.
Yu L, Chen J. Association of MHTFR Ala222Val (rs1801133) polymorphism and breast cancer susceptibility: An update meta-analysis based on 51 research studies. Diagn pathol 2012;7:171.
Li K, Li W, Dong X. Association of 677C>T (rs1801133) and 1298 A>C (rs1801131) polymorphisms in the MTHFR gene and breast cancer susceptibility: A meta-analysis based on 57 individual studies. PLoS One 2014;9:e71290.
Zhong S, Chen Z, Yu X, Li W, Tang J, Zhao J. A meta-analysis of genotypes and haplotypes of methylenetetrahydrofolate reductase gene polymorphisms in breast cancer. Mol Biol Rep 2014;41:5775-85.
Yan W, Zhang Y, Zhao E, Zhang S. Association between the MTHFR C677T polymorphism and breast cancer risk: A meta-analysis of 23 case–control studies. Breast J 2016;22:593-4.
Kumar P, Yadav U, Rai V. Methylenetetrahydrofolate reductase gene C677T polymorphism and breast cancer risk: Evidence for genetic susceptibility. Meta Gene 2015;6:72-84.
Xie SZ, Liu ZZ, Yu JH, Liu L, Wang W, Xie DL, et al
. Association between the MTHFR C677T polymorphism and risk of cancer: Evidence from 446 case-control studies. Tumour Biol 2015;36:8953-72.
Gonzales MC, Yu P, Shiao SP. MTHFR gene polymorphism-mutations and air pollution as risk factors for breast cancer: A metaprediction study. Nurs Res 2017;66:152-63.
Zhang Y, Jia H, Wang S, Jiang D. Cumulative review and meta-analyses on the association between MTHFR rs1801133 polymorphism and breast cancer risk: A pooled analysis of 83 studies with 74,019 participants. Minerva Med 2017;108:57-73.
Mo W, Ding Y, Zheng Y, Zou D, Ding X. Associations between folate metabolism enzyme polymorphisms and breast cancer: A meta-analysis. Breast J 2020;26:484-87.
Liang H, Yan Y, Li T, Li R, Li M, Li S, et al
. Methylenetetrahydrofolate reductase polymorphisms and breast cancer risk in Chinese population: A meta-analysis of 22 case-control studies. Tumour Biol 2014;35:1695-701.
Wang Y, Yang H, Gao H, Wang H. The association between methylenetetrahydrofolate reductase gene C677T polymorphisms and breast cancer risk in Chinese population. Tumour Biol 2015;36:9153-8.
Hao J, Zhao P. The association between methylenetetrahydrofolate reductase 677C>T polymorphisms and breast cancer susceptibility: A meta-analysis based on Chinese Han population. J Cancer Res Ther 2015;11 Suppl 1:C59-62.
Meneses-Sanchez P, Garcia-Hernandez SC, Porchia LM, Pérez-Fuentes R, Torres-Rasgado E, Del Angel Soto A, et al
. C677T and A1298C methylenetetrahydrofolate reductase polymorphisms and breast cancer susceptibility among Latinos: A meta-analysis. Breast Cancer 2019;26:602-11.
Rai V. The methylenetetrahydrofolate reductase C677T polymorphism and breast cancer risk in Asian populations. Asian Pac J Cancer Prev 2014;15:5853-60.
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]