|Year : 2010 | Volume
| Issue : 5 | Page : 219-223
Methylenetetrahydrofolate reductase polymorphism (c677t) in muslim population of eastern uttar pradesh, India
Vandana Rai, Upendra Yadav, Pradeep Kumar, Sushil Kumar Yadav
Human Molecular Genetics Laboratory, Department of Biotechnology, VBS Purvanchal University, Jaunpur - 222 001, Uttar Pradesh, India
|Date of Web Publication||25-Jul-2012|
Human Molecular Genetics Laboratory, Department of Biotechnology, VBS Purvanchal University, Jaunpur - 222 001, Uttar Pradesh
Objective : The aim of the present study was to investigate the distribution of methylenetetrahydrofolate reductase (C677T) polymorphism in the Muslim population of eastern Uttar Pradesh. Materials and Methods: Total 56 subjects were analysed for MTHFR C677T polymorphism. C677T mutation analysis was done according to the PCR-RFLP (Polymerase chain reaction-Restriction fragment length polymorphism) method. Results : The frequencies of three genotypes CC, CT, and TT were 0.857, 0.125, and 0.07, respectively, and the frequency of mutated T allele was found to be 0.080. Conclusion : Genotypes and allele frequencies revealed the low prevalence of MTHFR C677T polymorphism in Indian Muslims. C677T mutation has been suggested to be positively associated with the risk of several congenital and multifactorial disorders. The low frequency of T/T genotype in the Muslim population may be due to malnutrition in pregnant women, because of insufficient intake of folate is considered to be a survival disadvantage for foetuses with T/T genotype.
Keywords: C677T, genotype, MTHFR, PCR-RFLP, polymorphism
|How to cite this article:|
Rai V, Yadav U, Kumar P, Yadav SK. Methylenetetrahydrofolate reductase polymorphism (c677t) in muslim population of eastern uttar pradesh, India. Indian J Med Sci 2010;64:219-23
|How to cite this URL:|
Rai V, Yadav U, Kumar P, Yadav SK. Methylenetetrahydrofolate reductase polymorphism (c677t) in muslim population of eastern uttar pradesh, India. Indian J Med Sci [serial online] 2010 [cited 2014 Sep 30];64:219-23. Available from: http://www.indianjmedsci.org/text.asp?2010/64/5/219/98949
| ¤ Introduction|| |
Methylenetetrahydrofolate reductase (MTHFR) is key enzyme of folate and methionine metabolic cycles. MTHFR catalyzes the conversion of 5, 10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, which donates the methyl group for the conversion of homocysteine to methionine. Two clinically important mutations C677T and A1298C in MTHFR gene is reported to be associated with various pathological conditions. The MTHFR C677T polymorphism converts alanine to valine residue. This mutation decreases the enzymatic activity leading to high homocysteine level, and related to various disorders like Down syndrome,  Neural tube defect, , cleft lip and palate,  cardiovascular disease, , and pregnancy loss.  The frequency of 677T allele varies substantially in different regions of the world and among different ethnic groups. ,, Ample data on the frequency of this variant in European, American, and African populations are available, but at the same time, the frequency distribution patterns of the MTHFR variant in Asian populations are poorly examined. Several studies reported the T-allele frequency from different part of the India, ,,, but the C677T polymorphism frequency is not reported from the UP population so far. The aim of the present study was to determine the frequency of MTHFR C677T mutations in the Muslim population of eastern Uttar Pradesh. The Muslim population of eastern UP is well suited for genetic studies because of genetic diversity, higher birth rate and neonatal mortality rate, marital stability, and consanguineous marriages.
| ¤ Materials and Methods|| |
Blood samples were collected from randomly selected 56 healthy unrelated individuals belonging to Muslim religion of both the sexes (28 samples were of males and 28 samples were from females). All subjects gave their informed written consent and the study was approved by the Institutional Ethics Committee, VBS Purvanchal University, Jaunpur, India. A questionnaire was used to collect demographic information, personal medical history and family history. Genomic DNA was extracted according to the method of Bartlett and White  and analysis of the MTHFR C677T mutation was done by PCR-RFLP according to the methods of Frosst et al.  A length of 198 base pairs on exon 4 of the MTHFR gene was amplified using 5-TGA AGG AGA AGG TGT CTG CGG GA-3 as the forward primer and 5-AGG ACG GTG CGG TGA GAG TG-3 as the reverse primer. PCR conditions were as described by Frosst et al.  The C to T polymorphism at codon 677 introduces a restriction site for Hinf I. Allele frequencies were calculated by the gene counting method. Chi-square test was performed to test hardy-Weinberg equilibrium.
| ¤ Results|| |
Allele frequencies and genotype distributions revealed in the present study are presented in [Table 1]. The prevalence of CC, CT, and TT genotypes determined in the target population were 48 (85.71%), 7 (12.5%) and 1 (1.79%), respectively. The genotype frequencies of CC, CT, and TT were 0.857, 0.125, and 0.07, respectively. The frequency of mutated T allele was 0.080 and this polymorphism was compatible with Hardy-Weinberg equilibrium (x2 = 1.332; df=2; P=0.248). [Figure 1] shows an agarose gel illustrating the different genotypes of the C677T mutation. The wild-type CC showed a single band of 198 bp. The heterozygote CT showed two bands, one at the 198 and other at 175 base pair (the third band of 23 bp could not be visualized on the agarose gel) and TT homozygote showed a single band of 175 bp.
|Table 1: Distribution of MTHFR genotypes and allele frequencies among muslims|
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| ¤ Discussion|| |
T-allele frequency in the Muslim population of eastern UP (0.08) established by the present study is lower (0.18) compared to South Indian  and higher (0.03) when compared to North Indian.  Limited data of MTHFR C677T polymorphism is available about the Asian population like Japanese,  Chinese,  and Sri Lankan.  Numerous literature data are available about the T-allele frequency in European, African, and American populations. The T-allele frequency ranges from 0.20 to 0.55 in Europeans, , 0.11 to 0.35 in Americans,  0.063 to 0.094 in Africans, , and from 0.04 to 0.38 in Asian population.  Our findings in UP Muslim subjects correspond to the previous publications ,,,, which also showed the lower frequency of TT homozygotes.
A possible explanation for the low prevalence of C677T mutation in Muslims is the higher rate of removal (negative selection) of the mutant allele than its introduction in the population gene pool. Individuals with the MTHFR T/T genotype are considered to have increased dietary folate requirements because they have lower red cell folate levels compared with those without this genetic variant  and are found to have higher homocysteine levels.  Homozygous T/T genotype is associated with a two- to three-fold increased risk of recurrent early pregnancy loss, probably because of hyperhomocysteinemia in the absence of folate supplementation. Hyperhomocysteinemia is known to be a risk factor in women with unexplained recurrent early pregnancy loss. , Increased levels of maternal plasma homocysteine may cause early damage of decidual or chorionic vessels, leading to spontaneous abortion.  Thus, insufficient intake of folate in the pregnant women is considered to be a survival disadvantage for foetuses homozygous for the T allele.  Consanguineous marriages are common in Muslims so that the lethal T allele may attain homozygosity in this population. Due to malnutrition and folate deficiency foetuses with homozygous T/T genotype are eliminated by prenatal mortality/recurrent pregnancy loss by the process of negative selection (removal).  The higher prevalence of the T allele in developed countries especially European may be influenced by the apparent higher folic acid content in the food. , A folate supplementation program during pregnancy in western countries protect foetuses homozygous for the T allele against pregnancy loss,  resulting in an increase of the frequency of the T/T genotype  which in the long turn is harmful. The result of our study on MTHFR C677T polymorphism in the Muslim population supplement the variability of this gene worldwide and can serve as a basis for further associative investigations on the role of MTHFR in susceptibility to different multifactorial diseases in the populations of different ethnic descent. Screening of populations for this clinically important gene polymorphism is needed for proper counselling strategies.
| ¤ Acknowledgments|| |
We are grateful to the subjects who participated in the present study without their cooperation; this study could not be completed. The financial support from University Grants Commission, New Delhi (grant No. 32-548/2006(SR)) to Vandana Rai is gratefully acknowledged.
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