The A1298C Methylenetetrahydrofolate Reductase Gene Variant as a Susceptibility Gene for Non-Syndromic Conotruncal Heart Defects in an Indian Population

The Roles of Reduced Folate Carrier-1 (RFC1) A80G (rs1051266) Polymorphism in Congenital Heart Disease: A Meta-Analysis

Background

We performed the present study to better elucidate the correlation of reduced folate carrier-1 (RFC1) A80G (rs1051266) polymorphism with the risk of congenital heart disease (CHD).

Material/Methods

According to the designed search strategy, a systematic literature search was performed through the PubMed, Cochrane Library, Web of Science, EMBASE, CNKI, VIP, and Wan Fang databases to collect published case-control studies on the correlation between RFC1 A80G polymorphism and CHD. All relevant studies up to October 1, 2019 were identified. The odds ratio (OR) and 95% confidence interval (CI) of the genotype distribution were used as the effect indicators.

Results

A total of 6 eligible studies was finally included in our meta-analysis, including 724 children with CHD, 760 healthy children, 258 mothers of the children with CHD, and 334 mothers of healthy control children. The meta-analysis revealed that for fetal analysis, only in the heterozygous model (GA vs GG, OR=1.36, 95% CI [1.06, 1.75], P=0.02) was RFC1 A80G polymorphism associated with risk of CHD. In maternal analysis, 3 genetic models of RFC1 A80G polymorphism increased the risk of CHD: the allelic model (A vs G, OR=1.36, 95% CI [1.07, 1.71], P=0.01), the homozygote model (AA vs GG, OR=2.99, 95%CI [1.06, 8.41], P=0.04), and the dominance model (GA+AA vs GG, OR=1.53, 95%CI [1.08, 2.16], P=0.02).

Conclusions

The maternal RFC1 A80G polymorphism has a strong correlation with CHD. Compared with the G allele, the A allele increases the risk of CHD by 0.36-fold.

The roles of MTRR and MTHFR gene polymorphisms in congenital heart diseases: a meta-analysis

Background: We performed the present study to better elucidate the correlations of methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) gene polymorphisms with the risk of congenital heart diseases (CHD).

Methods: Eligible articles were searched in PubMed, Medline, Embase and CNKI. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to detect any potential associations of MTHFR and MTRR gene polymorphisms with CHD.

Results: A total of 47 eligible studies were finally included in our meta-analysis. Our overall analyses suggested that MTRR rs1801394, MTRR rs1532268, MTHFR rs1801131 and MTHFR rs1801133 polymorphisms were all significantly associated with the risk of CHD in certain genetic models. Further subgroup analyses according to ethnicity of study participants demonstrated that the MTRR rs1801394 polymorphism was significantly correlated with the risk of CHD only in Asians, whereas MTRR rs1532268, MTHFR rs1801133 and MTHFR rs1801131 polymorphisms were significantly correlated with the risk of CHD in both Asians and Caucasians.

Conclusions: Our findings indicated that MTRR rs1532268, MTHFR rs1801131 and MTHFR rs1801133 polymorphisms may affect the risk of CHD in Asians and Caucasians, while the MTRR rs1801394 polymorphism may only affect in risk of CHD in Asians.

Genetic variation in folate metabolism is associated with the risk of conotruncal heart defects in a Chinese population

Background

Conotruncal heart defects (CTDs) are a subgroup of congenital heart defects that are considered to be the most common type of birth defect worldwide. Genetic disturbances in folate metabolism may increase the risk of CTDs.

Methods

We evaluated five single-nucleotide polymorphisms (SNPs) in genes related to folic acid metabolism: methylenetetrahydrofolate reductase (MTHFR C677T and A1298C), solute carrier family 19, member 1 (SLC19A1 G80A), methionine synthase (MTR A2576G), and methionine synthase reductase (MTRR A66G), as risk factors for CTDs including various types of malformation, in a total of 193 mothers with CTD-affected offspring and 234 healthy controls in a Chinese population.

Results

Logistic regression analyses revealed that subjects carrying the TT genotype of MTHFR C677T, the C allele of MTHFR A1298C, and the AA genotype of SLC19A1 G80A had significant 2.47-fold (TT vs. CC, OR [95% CI] = 2.47 [1.42–4.32], p = 0.009), 2.05–2.20-fold (AC vs. AA, 2.05 [1.28–3.21], p = 0.0023; CC vs AA, 2.20 [1.38–3.58], p = 0.0011), and 1.68-fold (AA vs. GG, 1.68 [1.02–2.70], p = 0.0371) increased risk of CTDs, respectively. Subjects carrying both variant genotypes of MTHFR A1298C and SLC19A1 G80A had a higher (3.23 [1.71–6.02], p = 0.0002) increased risk for CTDs. Moreover, the MTHFR C677T, MTHFR A1298C, and MTRR A66G polymorphisms were found to be significantly associated with the risk of certain subtypes of CTD.

Conclusions

Our data suggest that maternal folate-related SNPs might be associated with the risk of CTDs in offspring.

MTHFR A1298C polymorphisms reduce the risk of congenital heart defects: a meta-analysis from 16 case-control studies

Background

Methylenetetrahydrofolate reductase (MTHFR) plays a crucial role in the hyperhomocysteinemia, which is a risk factor related to the occurrence of congenital heart defect (CHD). However, the association between MTHFR polymorphism and CHD has been inconclusive.

Methods

We conducted an updated meta-analysis to provide comprehensive evidence on the role of MTHFR A1298C polymorphism in CHD. Databases were searched and a total of 16 studies containing 2207 cases and 2364 controls were included.

Results

We detected that a significant association was found in the recessive model (CC vs. AA + AC: OR = 1.38, 95% CI: 1.10–1.73) for the overall population. Subgroup analysis showed that associations were found in patients without Down Syndrome in genetic models for CC vs. AA (OR = 1.47, 95% CI: 1.01–2.14), CC vs. AC (OR = 1.29, 95% CI: 1.00–1.66) and recessive model (OR = 1.44, 95% CI: 1.14–1.82). We conducted a meta-regression analysis, Galbraith plots and a sensitivity analysis to assess the sources of heterogeneity.

Conclusions

In summary, our present meta-analysis supports the MTHFR 1298C allele as a risk factor for CHD. However, further studies should be conducted to investigate the correlation of plasma homocysteine levels, enzyme activity, and periconceptional folic acid supplementation with the risk of CHD.

Electronic supplementary material

The online version of this article (10.1186/s13052-017-0425-1) contains supplementary material, which is available to authorized users.

HAND1 Loss-of-Function Mutation Causes Tetralogy of Fallot

As the most prevalent form of birth defect in humans worldwide, congenital heart disease (CHD) is responsible for substantial morbidity and is still the leading cause of birth defect-related demises. Increasing evidence demonstrates that genetic defects play an important role in the pathogenesis of CHD, and mutations in multiple genes, especially in those coding for cardiac core transcription factors, have been causally linked to various CHDs. Nevertheless, CHD is a genetically heterogeneous disease and the genetic determinants underpinning CHD in an overwhelming majority of patients remain elusive. In the current study, genomic DNA was extracted from venous blood samples of 165 unrelated patients with CHD, and the coding exons and splicing junction sites of the HAND1 gene, which encodes a basic helix-loop-helix transcription factor essential for cardiovascular development, were sequenced. As a result, a novel heterozygous mutation, p.R118C, was identified in a patient with tetralogy of Fallot (TOF). The missense mutation, which was absent in 600 referential chromosomes, altered the amino acid that was completely conserved evolutionarily. Biological assays with a dual-luciferase reporter assay system revealed that the R118C-mutant HAND1 protein had significantly reduced transcriptional activity when compared with its wild-type counterpart. Furthermore, the mutation significantly decreased the synergistic activation of a downstream target gene between HAND1 and GATA4, another cardiac core transcription factor associated with TOF. To our knowledge, this is the first report on the association of a HAND1 loss-of-function mutation with enhanced susceptibility to TOF in humans. The findings provide novel insight into the molecular etiology underlying TOF, suggesting potential implications for the improved prophylactic and therapeutic strategies for TOF.