Indian Journal of Human Genetics
Home Current Issue Archives Guidelines Subscriptions e-Alerts Login 
Users online: 17
Print this page  Email this page Small font sizeDefault font sizeIncrease font size

            Table of Contents  
Year : 2013  |  Volume : 19  |  Issue : 4  |  Page : 412-414

Prevalence of methylenetetrahydrofolate reductase 677 C-T polymorphism among mothers of Down syndrome children

Department of Human Genetics, Guru Nanak Dev University, Amritsar, Punjab, India

Date of Web Publication4-Jan-2014

Correspondence Address:
Anupam Kaur
Department of Human Genetics, Guru Nanak Dev University, Amritsar, Punjab
Login to access the Email id

Source of Support: University Grants Commission, New Delhi, India grant number F.37.190/2009 (SR), Conflict of Interest: None

DOI: 10.4103/0971-6866.124368

Get Permissions



Introduction: The relationship between chromosomal non-disjunction leading to aneuploidy and folate metabolism has drawn attention in the recent years. In this study, we examined the polymorphism in the gene encoding the folate metabolizing enzyme methylenetetrahydrofolate reductase (MTHFR), namely, 677 C-T in women having Down syndrome (DS) children.
Materials and Methods: The prevalence of these variant genotypes (MTHFR 677 C-T polymorphism) in women having DS children (case mothers) (n = 110) was compared with controls (n = 111) from Punjab. Genotyping was done using the polymerase chain reaction method followed by restriction fragment length polymorphism.
Results: In the present study, 1.8% of case mothers had TT genotype while none of the control mothers showed this genotype. T allele frequency among cases was 0.13 and 0.11 in controls. The Chi-square value showed a non-significant difference between cases and controls.
Conclusion: No association has been observed between 677 C-T polymorphism and risk of non-disjunction in case mothers. Detection of polymorphisms in more genes of folate pathway is required to find out the exact cause of non-disjunction.

Keywords: Down syndrome, methylenetetrahydrofolate reductase, polymorphism

How to cite this article:
Kaur A, Kaur A. Prevalence of methylenetetrahydrofolate reductase 677 C-T polymorphism among mothers of Down syndrome children. Indian J Hum Genet 2013;19:412-4

How to cite this URL:
Kaur A, Kaur A. Prevalence of methylenetetrahydrofolate reductase 677 C-T polymorphism among mothers of Down syndrome children. Indian J Hum Genet [serial online] 2013 [cited 2016 May 24];19:412-4. Available from:

   Introduction Top

The higher birth frequency of Down syndrome (DS) has been a subject of interest to clinicians and researchers due to its phenotypic expression. In addition to the advanced maternal age, studies have linked the increased frequency of polymorphism of methylenetetrahydrofolate reductase (MTHFR), 677 C-T in mothers with DS child. Abnormal folate and methyl metabolism can lead to deoxyribonucleic acid (DNA) hypomethylation and abnormal chromosomal segregation; researchers have observed that mothers with mutations in MTHFR and other genes in this pathway have elevated levels of plasma homocysteine. An increase in plasma homocysteine was found to be a risk factor for DS in several of the studies. There seems to be a geographic variation in MTHFR gene polymorphism. It appears that DS is attributable not only to meiotic non-disjunction in mothers, but also to the gene, nutritional and environmental factors.

The gene for MTHFR is located on chromosome 1 at the position 1p36.3 having 11 exons. The most common polymorphism associated with the risk of DS, neural tube defect, mental retardation, congenital malformations is 677 C-T in the exon 4. This missense mutation leads to the substitution of valine instead of alanine residue thus creating a new restriction site for Hinf I resulting in 677 C-T polymorphism. In individuals with CT genotype, enzyme activity is reduced to 35% while with TT genotype it is reduced to 70%. Reduced MTHFR activity results in increased requirement for folic acid to maintain homocysteine remethylation, which has been considered as the risk factor for non-disjunction. [1],[2] There is only one report on MTHFR polymorphism from North India, [3] whereas no data is available from Punjab. Thus, non-availability of data has prompted this first study on Punjabi population to establish the role of MTHFR polymorphism in women with DS children.

   Materials and Methods Top

Blood samples of 110 mothers having DS children and 111 mothers having normal children were collected. Mothers of DS children were selected after confirming trisomy in children by cytogenetic analysis. The control mothers had normal children and did not have any abortion. Informed consent and approval of institutional ethical committee was obtained before all the investigation. Detailed family history and pedigree analysis was done. Total genomic DNA was isolated from 2 ml peripheral blood lymphocyte by phenol extraction method, [4] with modifications. Polymerase chain reaction (PCR) was carried out for 677 C-T polymorphism using specific primers [5] and conditions as follows:



For 35 cycles at 95°C for 45 sec, 62°C for 30 s and 72°C for 45 s. The 198 bp fragment was obtained as PCR product and was subjected to the restriction digestion by the enzyme Hinf I (4U/reaction) at 37°C overnight. Restriction digestion products were then electrophoresed in 2.5% agarose gel followed by ethidium bromide staining. Heterozygotes (CT) produced 198 bp, 175 bp and 23 bp fragments, homozygous mutant (TT) produced 175 bp and 23 bp fragments, while homozygous (CC) wild produced only 198 bp fragment.

Genotypic and allelic frequencies were calculated under the assumption of Hardy's Weinberg Equilibrium. To compare cases and controls mothers, Pearson's Chi-square test was employed and to estimate relative risk for DS, odds ratio at 95% confidence interval was calculated. Analyses were performed using software (Statistical Package for the Social Sciences Inc. 10, Chicago, IL, USA).

   Results Top

A total of 110 cases and 111 controls mothers for 677 C-T genotyping were enrolled in the present study. The mean maternal age at the time of birth of DS child was 27.5 years, while it was 29.8 years in control mothers. In our study, 78.2% of DS mothers had CC genotype, 20% CT and 1.8% TT while 80.2% and 19.8% of control mothers had CC and CT genotype, respectively. None of the control mothers had TT genotype. The T allele frequencies among cases and controls were 0.13 and 0.11, respectively. The Chi-square (χ² - 2.064) showed a non-significant difference between cases and controls [Table 1]. No relative risk was observed between genotypes [Table 2].
Table 1: Allele and genotype distributions of 677 C-T polymorphism

Click here to view
Table 2: MTHFR 677 C-T odds ratio among cases and controls

Click here to view

   Discussion Top

The aim of the present study was to estimate T allele frequency among mothers of DS children from Punjab and to establish a link between the presence of T allele and risk of having DS children. The data for T allele frequency revealed a non-significant difference between cases and controls. The frequency of homozygous wild genotype (CC) was much higher in both cases (78.2%) and (χ² - 2.064) showed that 677 C-T polymorphism was not associated with DS. The results from our study were consistent with various studies. [2],[6],[7],[8],[9],[10],[11],[12],[13] Several reports have suggested that higher frequency of T allele is associated with risk of non-disjunction. [1],[2],[14],[15] Meguid et al. [15] reported higher genotypic frequencies (CT and TT) among cases as compared to controls with odds ratio of 2.34 and 2.75, respectively and similarly, Ruxandra et al. [16] observed a higher heterozygous and homozygous mutant genotypic frequencies among control mothers (45.7% and 15.2%) than cases (38.5% and 7.7%). According to van der Put et al. [17] single polymorphism (677 C-T) is not sufficient to increase the risk of DS but its association with other polymorphisms in folate metabolizing genes such as 1298 A-C may lead to increased risk of non-disjunction. It is further indicated by Devi et al. [18] and van der Put et al. [17] that individuals with genotype 677 TT always had 1298 AA genotype or vice versa, thus two alleles are always in trans-configuration. Non-significant association in the present study may be due to single polymorphism study. Thus, to establish association, study with other polymorphisms in folate metabolizing genes and large sample size is required. Since very limited data has been reported from North Indian population, such studies will help in generating a base line data and to develop tools aimed at evaluating the risk for younger women having DS child.

   Acknowledgments Top

We gratefully acknowledge the cooperation of the parents of DS children and the financial support from the University Grants Commission, New Delhi, India grant number F.37-190/2009 (SR) awarded to Anupam Kaur.

   References Top

1.James SJ, Pogribna M, Pogribny IP, Melnyk S, Hine RJ, Gibson JB, et al. Abnormal folate metabolism and mutation in the methylenetetrahydrofolate reductase gene may be maternal risk factors for Down syndrome. Am J Clin Nutr 1999;70:495-501.  Back to cited text no. 1
2.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.  Back to cited text no. 2
3.Kohli U, Arora S, Kabra M, Ramakrishnan L, Gulati S, Pandey RM. Prevalence of MTHFR C677T polymorphism in north Indian mothers having babies with Trisomy 21 Down syndrome. Downs Syndr Res Pract 2008;12:133-7.  Back to cited text no. 3
4.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.  Back to cited text no. 4
5.Cyril C, Rai P, Chandra N, Gopinath PM, Satyamoorthy K. MTHFR Gene variants C677T, A1298C and association with Down syndrome: A Case-control study from South India. Indian J Hum Genet 2009;15:60-4.  Back to cited text no. 5
[PUBMED]  Medknow Journal  
6.Stuppia L, Gatta V, Gaspari AR, Antonucci I, Morizio E, Calabrese G, et al. C677T mutation in the 5,10-MTHFR gene and risk of Down syndrome in Italy. Eur J Hum Genet 2002;10:388-90.  Back to cited text no. 6
7.O'Leary VB, Parle-McDermott A, Molloy AM, Kirke PN, Johnson Z, Conley M, et al. MTRR and MTHFR polymorphism: Link to Down syndrome? Am J Med Genet 2002;107:151-5.  Back to cited text no. 7
8.Boduroðlu K, Alanay Y, Koldan B, Tunçbilek E. Methylenetetrahydrofolate reductase enzyme polymorphisms as maternal risk for Down syndrome among Turkish women. Am J Med Genet A 2004;127A: 5-10.  Back to cited text no. 8
9.Chango A, Fillon-Emery N, Mircher C, Bléhaut H, Lambert D, Herbeth B, et al. No association between common polymorphisms in genes of folate and homocysteine metabolism and the risk of Down's syndrome among French mothers. Br J Nutr 2005;94:166-9.  Back to cited text no. 9
10.Mukhopadhyay K, Dutta S, Das Bhomik A. MTHFR gene polymorphisms analyzed in population from Kolkata, West Bengal. Indian J Hum Genet 2007;13:38.  Back to cited text no. 10
11.Dutta S, Das AB, Mukhopadhyay K. Risk of Down syndrome conferred by MTHFR C677T polymorphism: Ethnic variations. Indian J Hum Genet 2007;13:76-7.  Back to cited text no. 11
[PUBMED]  Medknow Journal  
12.Vranekoviæ J, Babiæ Bozoviæ I, Starceviæ Cizmareviæ N, Buretiæ-Tomljanoviæ A, Ristiæ S, Petroviæ O, et al . Functional inference of methylenetetrahydrofolate reductase gene polymorphisms on enzyme stability as a potential risk factor for Down syndrome in Croatia. Dis Markers 2010;28:293-8.  Back to cited text no. 12
13.Rai AK, Singh S, Mehta S, Kumar A, Pandey LK, Raman R. MTHFR C677T and A1298C polymorphisms are risk factors for Down's syndrome in Indian mothers. J Hum Genet 2006;51:278-83.  Back to cited text no. 13
14.Scala I, Granese B, Sellitto M, Salomè S, Sammartino A, Pepe A, et al. Analysis of seven maternal polymorphisms of genes involved in homocysteine/folate metabolism and risk of Down syndrome offspring. Genet Med 2006;8:409-16.  Back to cited text no. 14
15.Meguid NA, Dardir AA, Khass M, Hossieny LE, Ezzat A, El Awady MK. MTHFR genetic polymorphism as a risk factor in Egyptian mothers with Down syndrome children. Dis Markers 2008;24:19-26.  Back to cited text no. 15
16.Cretu R, Neagos D, Tutulan-Cunita A, Bohiltea LC, Stoian V. MTHFR gene poloymorphisms and prenatal risk of down syndrome. Alexandra Loan Guza, Genetics and Molecular Biology 2010;9:157-63.  Back to cited text no. 16
17.van der Put NM, Gabreëls F, Stevens EM, Smeitink JA, Trijbels FJ, Eskes TK, et al. A second common mutation in the methylenetetrahydrofolate reductase gene: An additional risk factor for neural-tube defects? Am J Hum Genet 1998;62:1044-51.  Back to cited text no. 17
18.Devi AR, Govindaiah V, Ramakrishna G, Naushad SM. Prevalence of methylenetetrahydrofolate reductase polymorphism in South Indian population. Curr Sci 2004;86:440-3.  Back to cited text no. 18


  [Table 1], [Table 2]


Print this article  Email this article


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Article in PDF (216 KB)
    Citation Manager
    Access Statistics
    Reader Comments
    Email Alert *
    Add to My List *
* Registration required (free)  

    Materials and Me...
    Article Tables

 Article Access Statistics
    PDF Downloaded53    
    Comments [Add]    

Recommend this journal