Translate this page into:
Methylene Tetrahydrofolate Reductase Gene Polymorphism in Pre-Eclampsia
, Odeyinka Olufunsho Odewusi1, Adeola Olanrewaju Oluboyo1, Emmanuel Akokhamen Omon1, Olusola Peter Aduloju2, Blessing Nene Oshobugie1
*Corresponding author: Obongama Okokon Edet, Department of Medical Laboratory Science, College of Medicine and Health Sciences, Afe Babalola University, AdoEkiti, Ekiti State, Nigeria. edetoo@abuad.edu.ng
-
Received: ,
Accepted: ,
How to cite this article: Edet OO, Odewusi OO, Oluboyo AO, Omon EA, Aduloju OP, Oshobugie BN. Methylene Tetrahydrofolate Reductase Gene Polymorphism in Pre-eclampsia. Indian J Cardiovasc Dis Women. 2026;11:17-23. doi: 10.25259/IJCDW_37_2025
Abstract
Objectives:
Pre-eclampsia is a hypertensive disease linked to pregnant women with severe maternal and perinatal consequences. The etiopathogenesis of pre-eclampsia is not clear and still controversial with investigations still ongoing. This study therefore aimed to determine the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism in women with pre-eclampsia in Ekiti State, South West, Nigeria.
Materials and Methods:
This was a case–control non-interventional study and 165 pregnant women with preeclampsia (subjects) and 135 normotensive healthy pregnant women (control) were studied. Demographic and anthropometric data were determined utilizing questionnaires and tools as appropriate, following standard operating procedures. Genomic DNA was extracted from blood samples that had been stored at −20°C, and genotypes of MTHFR C677T were analyzed using polymerase chain reaction and suitable restriction enzymes and were subsequently subjected to electrophoresis to determine the band size of alleles as per routine protocols.
Results:
There was no significant difference in the demographic characteristics between subjects and controls as per age and location (P = 0.456; P = 0.102). Anthropometric characteristics (systolic blood pressure, diastolic blood pressure, weight, body mass index, waist circumference, and hip circumference) were statistically significant (P = 0.000; P = 0.000; P = 0.012; P = 0.001; P = 0.043; P = 0.031), respectively. Those with mild pre-eclampsia were higher than those with severe pre-eclampsia (64.2% vs. 35.8%). Significant proteinuria was observed between subjects and controls (P = 0.011). Fetal death had the highest complication rate of 14.0%. The frequency of homozygous MTHFR C677T gene mutation in pre-eclampsia was significantly higher in subjects than in controls (P = 0.045).
Conclusion:
There was a statistically significant difference between subjects and controls in the MTHFR C677T gene polymorphism. In pregnant women with pre-eclampsia in Ekiti State, South West Nigeria, the MTHFR C677T gene polymorphism may play a role in the development and progression of pre-eclampsia. This study provides valuable corroboration of what has been previously noted in other population groups.
Keywords
Ekiti state
Gene polymorphism
Methylene tetrahydrofolate reductase
Pre-eclampsia
ABSTRACT IMAGE
INTRODUCTION
Pre-eclampsia is a hypertensive disease linked to pregnant women with severe maternal and perinatal consequences.[1] It is influenced by factors that include race, genes, parity status, and environmental factors with metabolic and immunologic influences contributing to its etiopathogenesis.[2,3] At present, a consensus has not been reached on its etiopathogenesis but there are considerations by various research scientists that its etiopathogenesis is not similar but could vary from one population to another.[4] In both biological and physiological presentations, it is basically a placental disturbance linked to dysfunction of the placenta with severe and varied obstetrics and gynecological outcomes.[5] Systematic reviews documented by Burton et al.[5] Rana et al.[6] show that risk factors are varied and include chronic hypertension, chronic kidney disease with physical, obstetrical, and educational-related concerns. Biological elements that enter the woman’s circulatory system due to defective placenta produce inflammatory and widespread vascular concerns.[7] About 8% of pregnancies are affected by pre-eclampsia in relation to the people and area being considered given the description for pre-eclampsia.[1] It is a major driver of the deaths of mothers and newborns in Africa inclusive of Nigeria.[2] In sub-Saharan Africa, the overall pooled incidence of pre-eclampsia was 13% with a 95% confidence interval (CI) of 0.12–0.14.[8] In Nigeria, the occurrence rate is 2–16% with high number of deaths yearly.[9] In Ado-Ekiti, South West Nigeria, the occurrence is 12.3% as stated.[10] Maternal complication or severe outcome was not observed in the majority of women in northern Nigeria.[11] Pre-eclampsia has important genetic elements and is associated with various and certain genes polymorphism. This is due to variants at specific sites with individual and collective vulnerability.[1,12] A study in Lagos by earlier authors[3] has identified that methylenetetrahydrofolate reductase (MTHFR) and methionine synthase mutations have been identified. Furthermore, another study by earlier authors[2] investigated mutations in exon 2 of the angiotensin gene in pre-eclamptic women in Calabar, South South, Nigeria, observed a deletion of guanine at position 26 in all pre-eclamptic women and also 5 transversion mutations of varying degrees using multiple sequence alignment. Another study in Tunisian pregnant women showed an interconnection between MTHFR gene mutation and raised threat of pre-eclampsia and mixed outcomes were seen in diverse tribal regions.[13] MTHFR translates 5–10-methylenetetrahydrofolate to 5-methyltetrahydrofolate and is related to homocysteine and folate conversion which is associated with DNA methylation. Various and established polymorphisms seen in the MTHFR gene locus are C677T (rs1801133) and A1298C (rs1801131) and reflect an inadequacy of specific bio-catalyst. The mutation can downregulate MTHFR action, alter the levels of homocysteine in blood, and bring about unusual worries about cognitive, circulatory, and nervous system impairments.[14,15] Raised plasma concentrations of homocysteine are linked to placental vascular disturbances and elevated fetal loss.[16] MTHFR gene has been identified in the chromosomal region 1P36.3 with fourteen usual or atypical single-nucleotide polymorphisms associated with enzyme alterations deformities with C677T and A1298C as regular genotypes. C677T variant is of medical value and is positioned at exon 4. C677T variant comes about as a result of the replacement of cytosine by thymine, progressing to the translation of valine to alanine at codon number 222 in the N-terminal catalytic domain. The homozygous MTHFR 677TT mutant genotype has been linked to a reduction in MTHFR enzyme up to 30% in vitro as compared to the wild type.[4] This study has not been previously done in Ekiti State, South West Nigeria and it becomes necessary to find and evaluate genetic polymorphism associated with C677T locus of the methylene tetrahydrofolate reductase gene in preeclamptic women as a genetic biomarker to further enhance early recognition and identification of pregnant women with threats associated with pre-eclampsia.
MATERIALS AND METHODS
Study subjects and area
This was a non-interventional case–control study carried out in various healthcare facilities in Ekiti State, South West, Nigeria. Ekiti State is situated entirely within the tropics with a population of 3.3 million persons (2016 est). The study recruited 165 pregnant women as subjects. The women were of comparable age and gestation with 135 healthy normotensive pregnant women and this served as the control group.
Inclusion and exclusion criteria
The inclusion criteria were pregnant women within the reproductive age at the time of the study and identified as preeclamptic between 13 and 27 weeks of pregnancy confirmed by laboratory and clinical data. Those who voluntarily agreed to participate in the study and also signed an informed consent document. This served as the subject.
The exclusion criteria were pregnant women with chronic hypertension and those with other clinical diseases such as diabetes, malaria, urinary tract infection, human immunodeficiency viral infection, and hepatitis B viral infection. Those who agreed to participate in the study but did not sign the informed consent document. Non-preeclamptic pregnant women and those without chronic hypertension served as control subjects.
Ethical consideration and approval
Ethical clearance was obtained from the College of Medicine and Health Sciences of the Afe Babalola University, AdoEkiti, Ekiti State Health Research Ethics Committee (ABUADHREC/26/04/2024/383) before proceeding for sample collection and informed consent was obtained from participants in this study. Study was carried out according to the Helsinki Declaration on Human Research.
Data, sample collection and analysis
Valuable demographic and anthropometric data, including other relevant history, were collected from participants. 5 mL of venous blood samples of subjects were collected into ethylenediaminetetraacetic acid bottles aseptically from the antecubital vein of the cubital fossa for molecular studies and then stored at −20°C before analysis. Urine samples were also collected from participants for evaluation of urine protein levels. DNA extraction, polymerase chain reaction, gel electrophoresis, purification of amplified product, and endonuclease digestion were done as per routine protocols. Primer sequence and restriction enzyme used in this study are F: TGAAGGAGAAGGTGTCTG CGGGA; R: AGGACGGTGCGGTGAGAG TG[4,17] and HinfI, respectively.
Statistics and analysis of data
All data were statistically summarized as mean and standard deviation and independent t-test. Subgroup correlations using Pearson correlation coefficient(r) were calculated to find the relationship between variables. One-way analysis of variance test was used to compare results between various groups (within groups and between groups) where appropriate. The Statistical Package for the Social Sciences statistical version 25 was used for the analysis and P < 0.05 was considered to be statistically significant.
RESULTS
165 pregnant women were included in the study group (subjects) while 135 pregnant women with healthy pregnancies were in the control group and results are as presented.
Demographic characteristics of the subjects and control
Table 1 shows the demographic characteristics of the subjects and the controls. Among the subjects, 54.5% belong to age group 20–30 years while 45.5% belong to age group 31–40 years. The subjects were more urban dwellers compared to rural dwellers at 148 (89.7%) and 99 (73.3%), respectively. There was no statistically significant difference between subjects and controls in age and location. However, a statistically significant difference (P = 0.011) was observed between subjects and controls for proteinuria.
| Parameters | Subjects (n=165) percentage | Control n=135 (%)percentage |
P-value |
|---|---|---|---|
| Age (years) | |||
| 20–30 | 90 (54.5) | 70 (51.9) | X2=1.356 |
| 31–40 | 75 (45.5) | 65 (48.1) | P=0.456 |
| Location | |||
| Urban | 148 (89.7) | 99 (73.3) | X2=1.669 |
| Rural | 17 (10.3) | 36 (26.7) | P=0.102 |
| Proteinuria | |||
| Positive | 69 (41.8) | 6 (4.4) | X2=6.687 |
| Negative | 96 (58.2) | 129 (95.6) | P=0.011* |
| Pestatus | |||
| Mild | 106 (64.2) | ||
| Severe | 59 (35.8) | ||
| Complications | |||
| Fetal death | 23 (14.0) | ||
| Acute kidney injury | 14 (8.5) | ||
| Blurred vision | 8 (4.8) | ||
| Miscarriage | 7 (4.2) | ||
| None | 113 (68.5) | ||
Anthropometric characteristics of the subjects and control
Figure 1 shows the descriptive/anthropometric characteristics of the subjects and controls. Systolic and diastolic blood pressure mean values were higher and significant between those with and without pre-eclampsia (P = 0.000). The result of the body mass index indicates that the subjects with preeclampsia were obese and significantly higher. Furthermore, the weight, waist circumference, and hip circumference of those with pre-eclampsia were significantly higher. (P = 0.012; 0.043; 0.031), respectively, while the waist–hip ratio was not statistically significant. No statistically significant difference was observed between age and height (P = 0.869; 0.432), respectively.
- Anthropometric characteristics of subjects and control. (SBP: systolic BP, DBP: diastolic BP, BMI: body mass index, WC: Waist circumference HPC: Hip circumference).
Genotype frequencies of the MTHFR C677T polymorphism among women with pre-eclampsia and control group.
Figure 2 shows genotype frequencies of the MTHFR C677T polymorphism among participants. There was a statistically significant difference between subjects and controls (P = 0.045) with an odd ratio of 6.83 (95% CI 0.84–25.29).
- Genotype frequencies of the methylene tetrahydrofolate reductase C677T polymorphism among women with pre-eclampsia and control group. (Y-Axis: cc: homozygous cytosine to cytosine; ct: heterozygous cytosine to thymine; tt: homozygous thymine to thymine.).
Frequency of genotypes in association with blood pressures of associated gene.
Table 2 shows the frequency of genotypes in association with blood pressures of associated gene among participants. Subjects with homozygous mutated Homozygous Thymine to thymine (TT) genotype were seen in the blood pressure range of 140–160 mmHg and 70–100 mmHg for systolic and diastolic blood pressures, respectively.
| BP | Subject n=165 (%) | Control n=135 (%) | OR (95%CI) | P-value | |
|---|---|---|---|---|---|
| 140–160 | >160 | 75–130 | |||
| BP systolic MTHFR | |||||
| C677T | |||||
| CC | 106 (64.2) | 51 (30.9) | 134 (99.3) | ||
| TT | 8 (4.8) | 0 (0.0) | 1 (0.7) | 6.83 (0.84–25.29) | 0.045 |
| CT | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||
| 70-100 | >100 | 40-90 | |||
| BP diastolic MTHFR | |||||
| C677T | |||||
| CC | 89 (53.9) | 68 (41.2) | 134 (99.3) | ||
| TT | 8 (4.8) | 0 (0.0) | 1 (0.7) | 6.83 (0.84–25.29) | 0.045 |
| CT | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||
BP: Blood pressure, MTHFR: Methylenetetrahydrofolate reductase, OR: Odds ratio, CI: Confidence interval. CC: Homozygous wild type (Cytosine). CC: Homozygous cytosine to cytosine; TT: Homozygous Thymine to thymine. The significance of the p value is p< 0.05 and the result in the text for p value =0.045 while the odds ratio (Confidence interval) is 6.83 (0.83 - 25.29)
Association between C677T in relation to the urine protein in subject and control group.
Table 3 shows the association between C677T in relation to the urine protein among participants. There was a reduced number of subjects with 2+ proteinuria compared with the homozygous wild type variant (P = 0.010) with a CI, 14.16 (95 CI: 0.81–47.56).
| MTHFR | Subject n=165 | Control n=135 | |||
|---|---|---|---|---|---|
| Proteinuria | n(%) | n(%) | |||
| C677T | + | ++ | Negative | + | Negative |
| Genotypes | |||||
| CC | 38 (23.0) | 23 (14.0) | 96 (58.2) | 6 (4.4) | 128 (94.8) |
| TT | 1 (0.6) | 7 (4.2) | 0 (0.0) | 0 (0.0) | 1 (0.74) |
| CT | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
MTHFR: Methylenetetrahydrofolate reductase, OR: Odds ratio, CI: Confidence interval. OR (95% Cl)=14.16 (0.81–47.56), P=0.010. +Mild, ++Moderate, CC: Homozygous wild type (Cytosine)
Figure 3 shows gel electrophoresis of the MTHFR mutation 198 bp (173bp, 25bp) fragment lengths.
- Methylene tetrahydrofolate reductase gel studies. (MTHFR: Methylene tetrahydrofolate reductase; PCR: Polymerase chain reaction; MK: Base pair marker; TT: Homozygous mutated thymine to thymine; CC: Homozygous cytosine to cytosine).
DISCUSSION
Pre-eclampsia is a complication of pregnancy. The data base for single nucleotide polymorphism (dbSNP) id of the variant rs1801133 (NM_005957.5:c.665C>T) was studied. The present study revealed the presence of homozygous mutated TT genotype of C677T. The homozygous mutated TT genotype of C677T and T allele polymorphism was higher in those with pre-eclampsia than control. In this regard, TT is deemed to be a risk genotype and a threat allele polymorphism linked to the disease progression. This result is not at variance with the study of Ibrahim et al.[16] Limited enzyme activity is found in persons with the TT genotype, leading to increased homocysteine and reduced folate levels.[18] Studies elsewhere in China found no statistical significant difference between subjects and control and inconsistent with our findings.[19] Moreso, the CC genotype of the C677T polymorphism and the C allele is determined to be a non-threat genotype and also a deficient risk allele polymorphism and could offer a protective effect linked to disease progression. This study also found that subjects had higher values of homozygous mutated TT genotype while those in the control group had higher values of the homozygous CC genotype for systolic and diastolic blood pressure. Urine protein levels of those with homozygous CC genotype were more in comparison to individuals with the homozygous mutated TT genotype. The result of the association between the frequency of homozygous mutated TT genotype and blood pressure is consistent with the findings of Kosmas et al.[20] It is therefore suggestive that the T allele may increase the possibility of systolic and diastolic blood pressure. In this study, the heterozygous CT mutant genotype was not seen. There is no immediate explanation for this but could be explained that this variant may not be present in the sample population being studied, perhaps also could be as a result of the sample size utilized for this study. This is similar to the study by Jansaka et al.,[21] which had an absence homozygous MM in their sample population in a study of angiotensinogen gene polymorphism and pre-eclampsia in Thai pregnant women. Varied frequency of MTHFR polymorphism in different ethnicities may contribute to the conflicting results of published studies on disease relationships of genetic MTHFR variants.[16]
CONCLUSION
This study is the first of its kind in this part of Nigeria given available data. There is a significant difference between subjects and controls in the MTHFR gene polymorphism. The study therefore concludes that MTHFR gene polymorphism may contribute to the development and progress of pre-eclampsia and could serve as a probable source of identifying women with pre-eclampsia from a population of women in Ekiti state, South West Nigeria. This study also provides valuable corroboration of what has been previously noted in other population groups. It is recommended that further studies should be done with a large sample size to further enhance the quality of study and to see if there are heterozygous mutant genotypes present in women from this part of Nigeria. The limitation of this study is that homocysteine and folate levels were not determined to explore gene–environment interactions which could further enhance the quality of the work.
Ethical approval:
The research/study was approved by the Institutional Review Board at Afe Babalola University Health Research Ethics Committee (HREC), number ABUADHREC/26/04/2024/383, dated March 18, 2024.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
References
- Genetic markers for preeclampsia in peruvian women. Colomb Med (Cali). 2021;52:e2014437.
- [CrossRef] [PubMed] [Google Scholar]
- Human AGT Mutations in pre-eclamptic women in Calabar, Nigeria. Saudi J Biomed Res. 2019;4:62-7.
- [Google Scholar]
- Methylene tetrahydrofolate reductase and methionine synthase gene polymorphisms as genetic determinants of pre-eclampsia. Pregnancy Hypertens. 2020;20:7-13.
- [CrossRef] [PubMed] [Google Scholar]
- Genotypic and phenotypic markers of pre-eclampsia: A folate based algorithm in pregnancy. Niger Hosp Pract. 2022;29:42-9.
- [Google Scholar]
- Preeclampsia: Pathophysiology and clinical implications. BMJ. 2019;366:I2381.
- [CrossRef] [PubMed] [Google Scholar]
- Preeclampsia: Pathophysiology, challenges and perspectives. Circ Res. 2019;124:1094-112.
- [CrossRef] [PubMed] [Google Scholar]
- Incidence, trends and risk factors of preeclampsia in Sub-Saharan Africa: A systematic review and meta-analysis. PAMJ One Health. 2023;11:1.
- [CrossRef] [Google Scholar]
- Knowledge, perception and management of pre-eclampsia among health care providers in a maternity hospital. Int J MCH AIDS. 2019;8:80-8.
- [CrossRef] [PubMed] [Google Scholar]
- Choosing cesarean section over natural birth: Challenges of decision making among pregnant women with pre-eclampsia in ado-ekiti. Pregnancy hypertens. 2022;30:97-102.
- [CrossRef] [PubMed] [Google Scholar]
- Prevalence and materno-fetal outcomes of preeclampsia/eclampsia amongst pregnant women at a teaching hospital in North-Central Nigeria: A retrospective cross-sectional study. Clin Hypertens. 2021;27:20.
- [CrossRef] [PubMed] [Google Scholar]
- Association of MTHFR C677T and A1298C variants with preeclampsia risk and angiogenic imbalance in Tunisian women. Pregnancy Hypertens. 2025;39:101187.
- [CrossRef] [PubMed] [Google Scholar]
- Impacts of maternal preeclampsia exposure on offspring neuronal development: Recent insights and interventional approaches. Int J Mol Sci. 2024;25:11062.
- [CrossRef] [PubMed] [Google Scholar]
- Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism: Epidemiology, metabolism and the associated diseases. Eur J Med Genet. 2015;58:1-10.
- [CrossRef] [PubMed] [Google Scholar]
- Methylenetetrahydrofolate C677T polymorphism and pre-eclamptic Egyptian women. Middle East Fertil Soc J. 2012;17:105-10.
- [CrossRef] [Google Scholar]
- Correlation between C677T and A1298C mutations on the MTHFR gene with plasma homocysteine levels and venous thrombosis in pregnant women at risk of thrombosis. Zahedan J Res Med Sci. 2015;17:e5192.
- [CrossRef] [Google Scholar]
- Global and population-specific association of MTHFR polymorphisms with preterm birth risk: A consolidated analysis of 44 studies. BMC Pregnancy Childbirth. 2025;25:230.
- [CrossRef] [PubMed] [Google Scholar]
- Association of methylenetetrahydrofolate reductase C677T polymorphism with the pre-eclampsia risk in Hakka pregnant women in Southern China. Gynecol Endocrinol. 2020;36:322-6.
- [CrossRef] [PubMed] [Google Scholar]
- Association of C677T polymorphism in the methylenetetrahydrofolate reductase gene with hypertension in pregnancy and pre-eclampsia: A meta-analysis. J Hypertens. 2004;22:1655-62.
- [CrossRef] [PubMed] [Google Scholar]
- A study of the association between angiotensinogen (AGT) gene polymorphism (M235T) and preeclampsia in Thai pregnant women. J Obstet Gynaecol. 2021;41:1062-66.
- [CrossRef] [PubMed] [Google Scholar]