(25) The Role of Maternal Folic Acid in Offspring Congenital Heart Defects

Background: Congenital heart defects (CHDs) are the most common birth defects and a leading cause of infant mortality. Although folic acid (FA) supplementation is well established in preventing neural tube defects, its role in CHDs remains poorly understood, and findings from epidemiologic studies have been inconsistent.

Objectives: We hypothesized that maternal FA intake influences embryonic heart development.

Design/Methods: To investigate this, we employed a comprehensive multi-omics approach—integrating methylomics, transcriptomics, proteomics, and phosphoproteomics—on embryonic mouse hearts exposed to high (10 ppm) or low (2 ppm) maternal FA diets. To further elucidate the impact of maternal FA on cardiac development, we examined its effects in a genetic model of CHD and performed neural crest lineage tracing to assess how FA levels influence the contribution of these cells to heart formation.

Results: Methyl-Seq identified 2,488 differentially methylated regions, particularly in regulatory elements such as promoters, with gene ontology analysis linking these to cardiac morphogenesis, cytoskeletal organization, and chromatin remodeling. RNA-Seq revealed 377 differentially expressed genes, including key cardiac regulators, with enrichment in pathways such as heart morphogenesis and ventricular septum development. Proteomic analysis identified 281 differentially expressed proteins, implicating EIF2 and mTOR signaling, while phosphoproteomic profiling highlighted changes in mRNA splicing, cytoskeletal dynamics, and RhoA GTPase signaling. Cross-omics integration revealed 68 overlapping genes/proteins and there were 80 overlapping pathways between methylomics and transcriptomics, 27 overlapping between methylomics and proteomics, 56 overlapping between transcriptomics and proteomics and 16 pathways were implicated in all three analyses. Prominent pathways include organ developmental process and anatomical structure morphogenesis. Using a Shroom3 gene defect mouse model, we demonstrated that low maternal FA intake increased the incidence of ventricular septal defects in genetically susceptible embryos. Notably, these effects were amplified into the second generation, suggesting transgenerational epigenetic inheritance that may have led to previous heterogeneity in epidemiologic studies.

Conclusions: Our findings provide mechanistic insight into how maternal FA influences cardiac development and CHD risk. These results support the use of integrated multi-omics approaches to unravel complex gene-environment interactions in CHD.