A narrative review on the role of folate-mediated one-carbon metabolism and its associated gene polymorphisms in posing risk to preeclampsia

Polymorphism of Folate Metabolism Genes among Ethnic Kazakh Women with Preeclampsia in Kazakhstan: A Descriptive Study

INTRODUCTION

Preeclampsia is a severe multifactorial complication of pregnancy. Studies found associations between folate metabolism genes' polymorphisms and preeclampsia. However, investigations in this field are limited among Asian populations. Thus, the study's aim was to evaluate the prevalence of methionine synthase (MTR), methionine synthase reductase (MTRR), and methylenetetrahydrofolate reductase (MTHFR) genes' polymorphisms among ethnic Kazakh women with preeclampsia.

METHODS

This was a retrospective study involving 4246 patients' data for the period of 2018-2022. Identification of MTR, MTRR, and MTHFR genes' polymorphism was performed via PR-PCR. Peripheral blood samples were obtained for the analyses. In total, 4246 patients' data of Kazakh ethnicity with preeclampsia at >20 weeks gestational age who had undergone an investigation to identify polymorphisms of the folate metabolism pathway genes for the period of 5 years were included in this study.

RESULTS

The most common and prevalent mutation was the MTRR A66G polymorphism: 24.5% of all tested patients with preeclampsia had the MTRR A66G polymorphism. It was highest among the 35-39 age group participants. The second most prevalent was the MTHFR C677T polymorphism: 9% of women with preeclampsia had the MTHFR C677T mutation. It was highest among women aged 30-34. There was a rare association of the MTR A2756G mutation with preeclampsia among the study participants.

CONCLUSIONS

The identified levels of MTRR A66G and MTHFR C677T polymorphisms among the study participants suggest the importance of evaluating MTRR and MTHFR polymorphisms in women with preeclampsia. The role of the MTR A2756G polymorphism in the development of preeclampsia needs to be further investigated.

The prevalence and linkage disequilibrium of 21 genetic variations related to thrombophilia, folate cycle, and hypertension in reproductive age women of Rostov region (Russia)

Several maternal genetic variations are known to play an important role during pregnancy since they can affect mother health and/or fetal growth. The frequency of these variants is variable among different populations. This study aimed to investigate thrombophilia, folate metabolism and hypertension genetic variants in reproductive age women of Rostov region (Russia) and then assess their linkage disequilibrium (LD) and heterogeneity among populations. A total of 3108 reproductive age women were included (33.75 ± 5.13 years). Twenty-one genetic variants were detected with RT-PCR. LD was tested according to (D') coefficient and p value. The highest frequency of mutant allele in studied population was as follows: PAI-1 rs1799768, MTRR rs1801394, AGT rs699, and AGTR2 rs1403543. We showed a high possibility of coinheritance of MTHFR rs1801133 with rs1801131 and AGT rs699 with rs4762 (D'=0.992 and 0.999, respectively). In addition, comparative analysis showed F7 rs6046, FGB rs1800790, MTR rs1805087, and AGT rs699 significantly more frequent among Rostov females by 1.3-1.5 times than European. MTHFR rs1801133, ADD1 rs4961, AGTR2 rs1403543, NOS3 rs2070744, and rs1799983 were with higher frequencies in Europeans than those in the studied group. Our data could be used as a reference for further associative studies of targeted genetic variations in different pregnancy complications specifically in this population.

Assessment of blood one-carbon metabolism indexes during mid-to-late pregnancy in 397 Chinese pregnant women

Objectives

One-carbon metabolism (OCM) significantly influences fetal growth and neurodevelopment through transferring methyl group to biomolecules, during which folate, methionine, choline and betaine function as methyl donor nutrients, while vitamin B2, B6, B12 function as enzyme cofactors, and homocysteine (Hcy) and S-adenosyl methionine (SAM) are functional metabolites. This study aimed to assess blood OCM index levels and explore their relationships among Chinese pregnant women.

Methods

Data were obtained from the baseline of the Mother-Child Nutrition and Health Cohort Study. Pregnant women, voluntarily recruited from September 2020 to June 2022 during antenatal examinations in five Chinese cities at 24-32 gestational weeks, provided fasting venous blood samples. Measurements included RBC and serum folate, serum vitamin B2, B6, B12, choline, betaine, methionine, total Hcy (tHcy), and plasma SAM. Sociodemographic characteristics and pregnancy-related conditions were collected via a self-designed questionnaire.

Results

Of 397 participants, 82.6% were in mid-pregnancy (24-27 gestational weeks) and 17.4% were in late-pregnancy (28-32 gestational weeks). Serum folate, vitamin B6, and B12 deficiencies were 2.5, 1.3, and 8.3%, respectively. Elevated tHcy (≥10 μmol/L) was observed in 1.8% of pregnant women. Elderly pregnant women (aged 35 and above) exhibited significantly lower serum methionine levels (p < 0.05), while multiparous women had lower RBC folate levels (p < 0.05), and lower serum methionine and vitamin B12 levels (p < 0.10, not statistically significant). Partial correlation analysis revealed positive associations between RBC folate and cofactor vitamin B12 (r = 0.244, p < 0.05) in the folate cycle, as well as significant correlations between two methyl donor paths [serum folate was significantly related to serum choline (r = 0.172) and betaine (r = 0.193)]. As functional biomarkers of OCM, serum tHcy exhibited negative associations with RBC folate (β = -0.330, p < 0.05) and vitamin B6 (β = -0.317, p < 0.05), and plasma SAM displayed a positive association with serum betaine (β = 0.610, p < 0.05), while negatively associated with serum vitamin B6 (β = -0.181, p < 0.05).

Conclusion

The blood OCM exhibited imbalances during mid-to-late pregnancy, characterized by lower levels of folate, vitamin B6, and B12, alongside elevated tHcy levels. Adequate folate and vitamin B6 emerged as significant predictors of lower tHcy levels. Additionally, serum betaine showed a positive correlation with plasma SAM. This suggests the importance of not only ensuring sufficient folate but also optimizing other OCM-related nutrients throughout pregnancy.

Interrelation among one-carbon metabolic (OCM) pathway-related indicators and its impact on the occurence of pregnancy-induced hypertension disease in pregnant women supplemented with folate and vitamin B12: Real-world data analysis

Background and objective

A considerable number of pregnant women who were supplemented with folate and vitamin B12 were selected as major participants in studying the one-carbon metabolic (OCM) pathway. Our study aimed to explore the effects of OCM-related indicators on pregnancy-induced hypertension (PIH) and preeclampsia (PE) in pregnant women with folate and vitamin B12 supplementation.

Subjects and methods

A total of 1,178 pregnant women who took multivitamin tablets containing 800 μg folate and 4 μg vitamin B12 daily from 3 months before pregnancy to 3 months after pregnancy were enrolled in this study. These pregnant women were classified into three groups: the normotensive group (n = 1,006), the PIH group (n = 131), and the PE group (n = 41). The information on age, weight, body mass index (BMI), number of embryos, gravidity, parity, and OCM-related indicators (serum level of homocysteine, folate, and vitamin B12; MTHFR C677T genotype) was collected.

Results

The accuracy of the prediction model based on the screened independent risk factors (hyperhomocysteine, OR = 1.170, 95% CI = 1.061-1.291; high folate status, OR = 1.018, 95% CI = 0.999-1.038; and high BMI, OR = 1.216, 95% CI = 1.140-1.297) for PIH in subjects with MTHFR CC genotype (AUC = 0.802) was obviously higher than that in subjects with MTHFR CT, TT genotype (AUC = 0.684,0.685, respectively) by receiver operating characteristic curve analysis. The homocysteine level of the PIH group was significantly higher than that of the normotensive group only in subjects with the MTHFR CC genotype (p = 0.005). A negative correlation between homocysteine and folate appeared in subjects with MTHFR CT + TT genotype (p = 0.005). A model including multiple embryos, nulliparas, and lower folate could predict the process from PIH to PE (AUC = 0.781, p < 0.0001).

Conclusion

The prediction model composed of homocysteine, folate, and BMI for PIH was suitable for subjects with MTHFR CC genotype in pregnant women with supplementation of folate and vitamin B12. Lower folate levels could be an independent risk factor in developing the process from PIH to PE.

One-carbon metabolism-related nutrients intake is associated with lower risk of preeclampsia in pregnant women: a matched case-control study

Many studies have suggested that folate plays a role in preeclampsia (PE) risks, but few studies have assessed folate-related 1-carbon metabolism (OCM)-related nutrients with the risk of PE. We hypothesized that OCM-related nutrients are associated with PE. A 1:1 matched case-control study was conducted to explore the association between dietary OCM-related nutrients intake and the risk of PE in pregnant Chinese women. Four hundred and forty pairs of pregnant women with PE and hospital-based, healthy pregnant women, matched according to gestational week (±1 week) and age (±3 years), were recruited. Dietary intake was assessed using a validated 78-item semiquantitative food frequency questionnaire. Multivariate conditional logistic regression was used to estimate odds ratios (ORs) and 95% CIs. Restricted cubic splines were plotted to evaluate the dose-response relationship between dietary OCM-related nutrient intake and the risk of PE. Intake of folate, vitamin B₆, vitamin B₁₂, methionine, and total choline were inversely related to the risk of PE after adjustment for covariates (all P trend < .05). Adjusted ORs (95% CIs) for quartile 4 versus quartile 1 were 0.71 (0.55-0.93) for folate, 0.66 (0.50-0.87) for vitamin B₆, 0.68 (0.52-0.88) for vitamin B₁₂, 0.77 (0.60-0.81) for methionine, and 0.67 (0.51-0.87) for total choline. This study suggests that dietary OCM-related nutrients intake is associated with lower odds of PE in pregnant Chinese women.