Distribution of Methionine Synthase Reductase (MTRR) Gene A66G Polymorphism in Indian Population


Methionine synthase reductase (MTRR) is an important enzyme of the folate/homocysteine pathway. It is responsible for regulation of methionine enzyme by reductive methylation. A common variant A66G is reported in the FMN-binding domain of the MTRR gene, which leads to substitution of isoleucine by methionine (I22M) in MTRR enzyme with reduced activity. Reduced catalytic activity of enzyme leads to high homocysteine concentration in blood and increases risk for numerous diseases. The frequency of A66G polymorphism varies in different ethnic groups. The present study has been designed to evaluate the frequency of MTRR A66G gene polymorphism in the Eastern UP population by PCR–RFLP method. Along with this we also performed a meta-analysis to evaluate the global prevalence of this polymorphism. Databases were screened to identified the eligible studies. The prevalence of the G allele and GG genotype was determined by the use of prevalence proportion with 95% CI. Open meta-analyst software was used for the meta-analysis. Total 1000 blood samples were analyzed, the frequencies of A and G alleles were 0.35 and 0.65 respectively. Meta-analysis results revealed that the prevalence of G allele and GG genotype were 49.4% (95% CI 40.6–58.1, p ≤ 0.001) and 24.3% (95% CI 17.8–30.9, p ≤ 0.001) respectively. In sub-group meta-analysis, the lowest frequency of G allele was found in South America (32.7%; 95% CI 14.1–51.3, p ≤ 0.001), and highest in Asia (56.4%; 95% CI 39.5–73.3, p ≤ 0.001). The results of the meta-analysis showed that the Asian population has the highest frequency of G allele and highest frequency of the GG genotype was found in the European population.

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Methionine synthase reductase


  1. 1.

    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 USA. 1997;94:3290–5.

    CAS  PubMed  Google Scholar 

  2. 2.

    James SJ, Pogribny IP, Pogribna M, Miller BJ, Jernigan S, Melnyk S. Mechanisms of DNA damage, DNA hypomethylation, and tumor progression in the folate/methyl-deficient rat model of hepatocarcinogenesis. J Nutr. 2003;133(11Suppl.1):3740S–7S.

    CAS  PubMed  Google Scholar 

  3. 3.

    Pogribny IP, James SJ, Jernigan S, Pogribna M. Genomic hypomethylation is specific for preneoplastic liver in folate/methyl deficient rats and does not occur in non-target tissues. Mutat Res. 2004;548(1–2):53–9.

    CAS  PubMed  Google Scholar 

  4. 4.

    Duthie SJ, Narayanan S, Brand GM, Pirie L, Grant G. Impact of folate deficiency on DNA stability. J Nutr. 2002;132(8 Suppl.):2444S–9S.

    CAS  PubMed  Google Scholar 

  5. 5.

    Zijno A, Andreoli C, Leopardi P, Marcon F, Rossi S, Caiola S, et al. Folate status, metabolic genotype, and biomarkers of genotoxicity in healthy subjects. Carcinogenesis. 2003;24:1097–103.

    CAS  PubMed  Google Scholar 

  6. 6.

    Parry JM, Al-Obaidly A, Al-Walhaib M, Kayani M, Nabeel T, Strefford J, et al. Spontaneous and induced aneuploidy, considerations which may influence chromosome malsegregation. Mutat Res. 2002;504(1–2):119–29.

    CAS  PubMed  Google Scholar 

  7. 7.

    Rosenquist TH, Ratashak SA, Selhub J. Homocysteine induces congenital defects of the heart and neural tube: effect of folic acid. Proc Natl Acad Sci USA. 1996;93:15227–32.

    CAS  PubMed  Google Scholar 

  8. 8.

    Leclerc D, Wilson A, Dumas R, Gafuik C, Song D, Watkins D, et al. Cloning and mapping of a cDNA for methionine synthase reductase, a flavoprotein defective in patients with homocystinuria. Proc Natl Acad Sci USA. 1998;95:3059–64.

    CAS  PubMed  Google Scholar 

  9. 9.

    Wilson A, Platt R, Wu Q, Leclerc D, Christensen B, Yang H, et al. A common variant in methionine synthase reductase combined with low cobalamin (vitamin B12) increases risk for spina bifida. Mol Genet Metab. 1999;67(4):317–23.

    CAS  PubMed  Google Scholar 

  10. 10.

    Hobbs CA, Sherman SL, Yi P, Hopkins SE, Torfs CP, Hine RJ, et al. Polymorphisms in genes involved in folate metabolism as maternal risk factors for Down syndrome. Am J Hum Genet. 2000;67:623–30.

    CAS  PubMed  PubMed Central  Google Scholar 

  11. 11.

    Brown CA, McKinney KQ, Kaufman JS, Gravel RA, Rozen R. A common polymorphism in methionine synthase reductase increases risk of premature coronary artery disease. J Cardiovasc Risk. 2000;7(3):197–200.

    CAS  PubMed  Google Scholar 

  12. 12.

    Fang Y, Zhang R, Zhi X, Zhao L, Cao L, Wang Y, et al. Association of main folate metabolic pathway gene polymorphisms with neural tube defects in Han population of Northern China. Childs Nerv Syst. 2018;34(4):725–9.

    PubMed  Google Scholar 

  13. 13.

    Cai CQ, Fang YL, Shu JB, Zhao LS, Zhang RP, Cao LR, et al. Association of neural tube defects with maternal alterations and genetic polymorphisms in one-carbon metabolic pathway. Ital J Pediatr. 2019;45(1):37.

    PubMed  PubMed Central  Google Scholar 

  14. 14.

    Su J, Li Z. Analysis of MTR and MTRR gene polymorphisms in Chinese patients with ventricular septal defect. Appl Immunohistochem Mol Morphol. 2018;26(10):769–74.

    CAS  PubMed  PubMed Central  Google Scholar 

  15. 15.

    McCaddon A, Davies G, Hudson P, Tandy S, Cattell H. Total serum homocysteine in senile dementia of Alzheimer type. Int J Geriatr Psychiatry. 1998;13(4):235–9.

    CAS  PubMed  Google Scholar 

  16. 16.

    Applebaum J, Shimon H, Sela BA, Belmaker RH, Levine J. Homocysteine levels in newly admitted schizophrenic patients. J Psychiatr Res. 2004;38:413–6.

    PubMed  Google Scholar 

  17. 17.

    Kim YR, Hong SH. Associations of MTRR and TSER polymorphisms related to folate metabolism with susceptibility to metabolic syndrome. Genes Genom. 2019;41(8):983–91.

    CAS  Google Scholar 

  18. 18.

    Murthy J, Gurramkonda VB, Lakkakula BVKS. Genetic variant in MTRR A66G, but not MTR A2756G, is associated with risk of non-syndromic cleft lip and palate in Indian population. J Oral Maxillofac Surg Med Pathol. 2015;27:782–5.

    Google Scholar 

  19. 19.

    Bartlett JMS, White A. Extraction of DNA from whole blood. In: Bartlett JMS, Stirling D, editors. Methods in molecular biology: PCR protocols, vol. 226. 2nd ed. Totowa: Humana Press Inc; 2003. p. 29–31.

    Google Scholar 

  20. 20.

    Abramson JH. WINPEPI updated: computer programs for epidemiologists, and their teaching potential. Epidemiol Perspect Innov. 2011;8:1.

    PubMed  PubMed Central  Google Scholar 

  21. 21.

    Mantel N, Haenszel W. Statistical aspects of the analysis of data from retrospective studies of disease. J Natl Cancer Inst. 1959;22(4):719–48.

    CAS  PubMed  PubMed Central  Google Scholar 

  22. 22.

    DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials. 1986;7:177–88.

    CAS  PubMed  PubMed Central  Google Scholar 

  23. 23.

    Whitehead A. Meta-analysis of controlled clinical trials. West Sussex: Wiley; 2002.

    Google Scholar 

  24. 24.

    Wallace BC, Dahabreh IJ, Trikalinos TA, Lau J, Trow P, Schmid CH. Closing the gap between methodologists and end-users: R as a computational back-end. J Stat Softw. 2013;49:1–15.

    Google Scholar 

  25. 25.

    StatPlanet software. http://www.statsilk.com/software/statplanet.

  26. 26.

    Rady PL, Szucs S, Grady J, Hudnall SD, Kellner LH, Nitowsky H, et al. Genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) in ethnic populations in Texas; a report of a novel MTHFR polymorphic site, G1793A. Am J Med Genet. 2002;107:162–8.

    PubMed  Google Scholar 

  27. 27.

    Vaughn JD, Bailey LB, Shelnutt KP, Dunwoody KM, Maneval DR, Davis SR, et al. Methionine synthase reductase 66A → G polymorphism is associated with increased plasma homocysteine concentration when combined with the homozygous methylenetetrahydrofolate reductase 677C → T variant. J Nutr. 2004;134:2985–90.

    CAS  PubMed  Google Scholar 

  28. 28.

    Tsai MY, Loria CM, Cao J, Kim Y, Siscovick DS, Schreiner PJ, et al. Polygenic association with total homocysteine in the post-folic acid fortification era: the CARDIA study. Mol Genet Metab. 2009;98:181–6.

    CAS  PubMed  PubMed Central  Google Scholar 

  29. 29.

    Gaughan DJ, Kluijtmans LA, Barbaux S, McMaster D, Young IS, Yarnell JW, et al. The methionine synthase reductase (MTRR) A66G polymorphism is a novel genetic determinant of plasma homocysteine concentrations. Atherosclerosis. 2001;157(2):451–6.

    CAS  PubMed  Google Scholar 

  30. 30.

    Gra O, Mityaeva O, Berdichevets I, Kozhekbaeva Z, Fesenko D, Kurbatova O, et al. Microarray-based detection of CYP1A1, CYP2C9, CYP2C19, CYP2D6, GSTT1, GSTM1, MTHFR, MTRR, NQO1, NAT2, HLA-DQA1, and AB0 allele frequencies in native Russians. Genet Test Mol Biomark. 2010;14:329–42.

    CAS  Google Scholar 

  31. 31.

    Rai PS, Murali TS, Vasudevan TG, Prasada SK, Bhagavath AK, Pai P, et al. Genetic variation in genes involved in folate and drug metabolism in a south Indian population. Indian J Hum Genet. 2011;17(Suppl 1):S48–53.

    CAS  PubMed  PubMed Central  Google Scholar 

  32. 32.

    Ghodke Y, Chopra A, Shintre P, Puranik A, Joshi K, Patwardhan B. Profiling single nucleotide polymorphisms (SNPs) across intracellular folate metabolic pathway in healthy Indians. Indian J Med Res. 2011;133:274–9.

    CAS  PubMed  PubMed Central  Google Scholar 

  33. 33.

    Rai V, Yadav U, Kumar P, Gupta S. Methionine synthase reductase A66G polymorphism in rural population of Uttar Pradesh (India). Biotechnology. 2011;10(2):220–3.

    CAS  Google Scholar 

  34. 34.

    Rai V, Yadav U, Kumar P. MTRR A66G polymorphism among two caste groups of Uttar Pradesh (India). Indian J Med Sci. 2012;66(5):136–40.

    PubMed  Google Scholar 

  35. 35.

    Rai V, Yadav U, Kumar P, Yadav SK. Analysis of methionine synthase reductase polymorphism (A66G) in Indian Muslim population. Indian J Hum Genet. 2013;19(2):183–7.

    CAS  PubMed  PubMed Central  Google Scholar 

  36. 36.

    Yang B, Liu Y, Li Y, Fan S, Zhi X, Lu X, et al. Geographical distribution of MTHFR C677T, A1298C and MTRR A66G gene polymorphisms in China: findings from 15357 adults of Han nationality. PLoS ONE. 2013;8:e57917.

    CAS  PubMed  PubMed Central  Google Scholar 

  37. 37.

    Ni J, Liu Y, Zhou T, Wu X, Wang X. Single nucleotide polymorphisms in key one-carbon metabolism genes and their association with blood folate and homocysteine levels in a Chinese population in Yunnan. Genet Test Mol Biomark. 2018;22(3):193–8.

    CAS  Google Scholar 

  38. 38.

    Barbosa PR, Stabler SP, Machado AL, Braga RC, Hirata RD, Hirata MH, et al. Association between decreased vitamin levels and MTHFR, MTR and MTRR gene polymorphisms as determinants for elevated total homocysteine concentrations in pregnant women. Eur J Clin Nutr. 2008;62:1010–21.

    CAS  PubMed  Google Scholar 

  39. 39.

    Steluti J, Carvalho AM, Carioca AAF, Miranda A, Gattás GJF, Fisberg RM, et al. Genetic variants involved in one-carbon metabolism: polymorphism frequencies and differences in homocysteine concentrations in the folic acid fortification era. Nutrients. 2017;9(6):E539.

    PubMed  Google Scholar 

  40. 40.

    Rai V. Polymorphism in folate metabolic pathway gene as maternal risk factor for Down syndrome. Int J Biol Med Res. 2011;2(4):1055–60.

    Google Scholar 

  41. 41.

    Amorim MR, Lima MA. MTRR 66A > G polymorphism as maternal risk factor for Down syndrome: a meta-analysis. Genet Test Mol Biomark. 2013;17(1):69–73.

    CAS  Google Scholar 

  42. 42.

    Yadav U, Kumar P, Yadav SK, Mishra OP, Rai V. Polymorphisms in folate metabolism genes as maternal risk factor for neural tube defects: an updated meta-analysis. Metab Brain Dis. 2015;30(1):7–24.

    CAS  PubMed  Google Scholar 

  43. 43.

    Kumar P, Yadav U, Rai V. Prevalence of glucose-6-phosphate dehydrogenase deficiency in India: an updated meta-analysis. Egypt J Med Hum Genet. 2016;17:295–302.

    Google Scholar 

  44. 44.

    Rai V. Genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) gene and susceptibility to depression in Asian population: a systematic meta-analysis. Cell Mol Biol. 2014;60(3):29–36.

    CAS  PubMed  Google Scholar 

  45. 45.

    Rai V. Strong association of C677T polymorphism of methylenetetrahydrofolate reductase gene with nosyndromic cleft lip/palate (nsCL/P). Ind J Clin Biochem. 2018;33(1):5–15.

    CAS  Google Scholar 

  46. 46.

    Rai V. Folate pathway gene methylenetetrahydrofolate reductase C677T polymorphism and Alzheimer disease risk in Asian population. Indian J Clin Biochem. 2016;31:245–52.

    CAS  PubMed  Google Scholar 

  47. 47.

    Rai V, Kumar P. Methylenetetrahydrofolate reductase C677T polymorphism and risk of male infertility in Asian population. Ind J Clin Biochem. 2017;32(3):253–60.

    CAS  Google Scholar 

  48. 48.

    Rai V. Methylenetetrahydrofolate reductase A1298C polymorphism and breast cancer risk: a meta-analysis of 33 studies. Ann Med Health Sci Res. 2014;4(6):841–51.

    CAS  PubMed  PubMed Central  Google Scholar 

  49. 49.

    Rai V, Yadav U, Kumar P. Impact of catechol-O-methyltransferase Val 158Met (rs4680) polymorphism on breast cancer susceptibility in Asian population. Asian Pac J Cancer Prev. 2017;18(5):1243–50.

    PubMed  PubMed Central  Google Scholar 

  50. 50.

    Rai V. Evaluation of the MTHFR C677T polymorphism as a risk factor for colorectal cancer in Asian populations. Asian Pac J Cancer Prev. 2016;16(18):8093–100.

    Google Scholar 

  51. 51.

    Kumar P, Rai V. MTHFR C677T polymorphism and risk of esophageal cancer: an updated meta-analysis. Egypt J Med Hum Genet. 2018;19:273–84.

    Google Scholar 

  52. 52.

    Yadav U, Kumar P, Rai V. Role of MTHFR A1298C gene polymorphism in the etiology of prostate cancer: a systematic review and updated meta-analysis. Egypt J Med Hum Genet. 2016;17(2):141–8.

    Google Scholar 

  53. 53.

    Yadav U, Kumar P, Rai V. NQO1 Gene C609T polymorphism (dbSNP: rs1800566) and digestive tract cancer risk: a meta-analysis. Nutr Cancer. 2018;70(4):557–68.

    CAS  PubMed  Google Scholar 

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Yadav, U., Kumar, P. & Rai, V. Distribution of Methionine Synthase Reductase (MTRR) Gene A66G Polymorphism in Indian Population. Ind J Clin Biochem 36, 23–32 (2021). https://doi.org/10.1007/s12291-019-00862-9

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  • Methionine synthase reductase
  • MTRR
  • A66G
  • Polymorphism
  • Genotyping