Study on Maternal SNPs of MTHFR Gene and HCY Level Related to Congenital Heart Diseases

Parental genetic effects on the offspring's phenotype without transmission of the gene itself-pathophysiology and clinical evidence

Parental genes can influence the phenotype of their offspring through genomic-epigenomic interactions even without the direct inheritance of specific parental genotypes. Maternal genetic variations can affect the ovarian and intrauterine environments and potentially alter lactation behaviors, impacting offspring nutrition and health outcomes independently of the fetal genome. Similarly, paternal genetic changes can affect the endocrine system and vascular functions in the testes, influencing sperm quality and seminal fluid composition. These changes can initiate early epigenetic modifications in sperm, including alterations in microRNAs, tRNA-derived small RNAs (tsRNAs), and DNA methylation patterns. These epigenetic modifications might induce further changes in target organs of the offspring, leading to modified gene expression and phenotypic outcomes without transmitting the original parental genetic alterations. This review presents clinical evidence supporting this hypothesis and discusses the potential underlying molecular mechanisms. Parental gene-offspring epigenome-offspring phenotype interactions have been observed in neurocognitive disorders and cardio-renal diseases.

Association between MTHFR C677T variant and risk for congenital heart defects in Egyptian children: a case–control study including meta-analysis based on 147 cases and 143 controls

Background

Stratification analysis studies showed that ethnicity has a significant association regarding MTHFR C677T variant and congenital heart diseases (CHDs) risk, and many published studies have controversial conclusions toward this association.

Methods

In this study, the association between the MTHFR C677T variant and the risk for CHDs was evaluated in 91 children with CHD and 95 healthy controls, as new cases, by using restriction fragment length polymorphism (RFLP) technique. Besides that, 2 case–control studies in the Egyptian population published before 2021 were included in this meta-analysis. The association was assessed by the odds ratio (OR) with a 95% confidence interval (CI) based on 294 alleles in CHD cases and 286 alleles in controls.

Results

The overall meta-analysis showed a significant association between MTHFR C677T variant and CHDs risk in Egyptian children with heterogeneity (Heterogeneity = 0.001) in all the genetic models with the highly significant association in T versus C allele (pooled OR 1.89, 95% CI 1.31–2.74; p value < 0.0004). The consistency of the genotypes was detected by Hardy–Weinberg equilibrium (HWE).

Conclusions

Our results support the MTHFR -677T allele as a susceptibility factor for CHDs in the Egyptian pediatric patients.

Association of MTHFR C667T Polymorphism, Homocysteine, and B Vitamins with Senile Cataract

Senile cataract has become the leading cause of visual impairment and even blindness in the world, but there are few reports on its relationship with methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms. This study is aimed to investigate the correlation between MTHFR gene polymorphisms or its enzyme metabolites and senile cataract. From January 2019 to June 2020, 663 patients with senile cataract at the Mianyang Central Hospital were enrolled as the observation group, and 646 healthy subjects were randomly selected as the control group. MTHFR gene polymorphisms (i.e., CC, CT, or TT genotypes) and serum homocysteine (HCY), folic acid (FOL), vitamin B12 (VitB12), and vitamin B6 (VitB6) levels were detected. The mutation rate of MTHFR C677T and HCY levels in the observation group were significantly higher than those in the control group, whereas FOL, VitB12, and VitB6 were significantly lower. With an increase in the MTHFR C677T mutation, HCY showed an upward trend, whereas FOL and VitB12 showed a decreasing trend in both the observation and control groups. Multiple logistic regression analysis showed that HCY and FOL were associated with senile cataract and MTHFR mutations; VitB12 was only associated with senile cataract. Compared to that with the CC genotype, CT and TT genotypes were associated with an increased senile cataract risk. Monitoring MTHFR gene polymorphisms and changes in serum HCY, FOL, and VitB12 levels could provide references in predicting senile cataract.

Study of variants associated with ventricular septal defects (VSDs) highlights the unique genetic structure of the Pakistani population

Background

Ventricular septal defects (VSDs) are one of the leading causes of death due to cardiac anomalies during the first months of life. The prevalence of VSD in neonates is reported up to 4%. Despite the remarkable progress in medication, treatment and surgical procedure for VSDs, the genetic etiology of VSDs is still in infancy because of the complex genetic and environmental interactions.

Methods

Three hundred fifty subjects (200 VSD children and 150 healthy controls) were recruited from different pediatric cardiac units. Pediatric clinical and demographic data were collected. A total of six variants, rs1017 (ISL1), rs7240256 (NFATc1), rs36208048 (VEGF), variant of HEY2, rs11067075 (TBX5) and rs1801133 (MTHFR) genes were genotyped by tetra-ARMS PCR and PCR–RFLP methods.

Results

The results showed that in cases, the rs1017 (g.16138A > T) variant in the ISL1 gene has an allele frequency of 0.42 and 0.58 respectively for the T and A alleles, and 0.75 and 0.25 respectively in the controls. The frequencies of the AA, TA and TT genotypes were, 52%, 11% and 37% in cases versus 21%, 8% and 71% respectively in the controls. For the NFATc1 variant rs7240256, minor allele frequency (MAF) was 0.43 in cases while 0.23 in controls. For the variant in the VEGF gene, genotype frequencies were 0% (A), 32% (CA) and 68% (CC) in cases and 0.0%, 33% and 67% respectively in controls. The allele frequency of C and A were 0.84 and 0.16 in cases and 0.83 and 0.17 respectively in controls. The TBX5 polymorphism rs11067075 (g.51682G > T) had an allelic frequency of 0.44 and 0.56 respectively for T and G alleles in cases, versus 0.26 and 0.74 in the controls. We did not detect the presence of the HEY2 gene variant (g.126117350A > C) in our pediatric cohort. For the rs1801133 (g.14783C > T) variant in the MTHFR gene, the genotype frequencies were 25% (CC), 62% (CT) and 13% (TT) in cases, versus 88%, 10% and 2% in controls. The ISL1, NFATc1, TBX5 and MTHFR variants were found to be in association with VSD in the Pakistani pediatric cohort whilst the VEGF and HEY2 variants were completely absent in our cohort.

Conclusion

We propose that a wider programme of genetic screening of the Pakistani population for genetic markers in heart development genes would be helpful in reducing the risk of VSDs.

Association of methylenetetrahydrofolate reductase gene polymorphisms and maternal folic acid use with the risk of congenital heart disease

BACKGROUND

To systematically evaluate the association of MTHFR genetic polymorphisms, maternal folic acid intake, and the time when folic acid intake was started with the risk of congenital heart disease (CHD) and investigated the role of their interaction on infant CHD risk in Chinese populations.

METHODS

A case-control study involving 592 CHD cases, 617 health controls, and their mothers was performed. The exposures of interest were single nucleotide polymorphisms (SNPs) of the MTHFR gene, maternal folic acid use, and the time when folic acid use was started. We applied the logistic regression model to explore the strength of association.

RESULTS

Our findings showed that mothers lacking folic acid intake had a significantly higher risk of CHD in offspring (aOR = 2.00; 95%CI: 1.34-2.98). Mothers who started to use folic acid from the first trimester of the fetation (aOR = 1.65; 95% CI: 1.22-2.23) or from the second trimester of the fetation (aOR = 7.77; 95% CI: 2.52-23.96), compared with those starting to use folic acid from 3 months previous to the conception, were at a significantly higher risk of CHD in offspring. Genetic variants at rs2066470 (AA vs. GG: aOR = 5.09, 95%CI: 1.99-13.03), rs1801133 (AA vs. GG: aOR = 2.49, 95%CI: 1.58-3.93), and rs1801131 (TG vs. TT: aOR = 1.84, 95%CI: 1.36-2.50; GG vs. TT: aOR = 3.58, 95%CI: 1.68-7.63) were significantly associated with the risk of CHD based on the multivariate analysis. Additionally, statistically significant interactions between maternal folic acid intake and genetic variants of the MTHFR gene at rs1801133 and rs1801131 were observed.

CONCLUSION

An association of maternal folic acid intake and the time when intake was started with the risk of CHD in offspring was found. What's more, maternal folic acid fortification may help counteract partial of the risks of CHD in offspring attributable to MTHFR genetic mutations.

REGISTRATION NUMBER

http://www.chictr.org.cn/edit.aspx?pid=28300&htm=4, identifier: ChiCTR1800016635.