Maternal Vitamin C Deficiency and Genetic Risk Factors Contribute to Congenital Defects through Dysregulation of DNA Methylation.

Maternal dietary insufficiencies can reshape the fetal epigenome during gestation, contributing to birth defects and developmental disorders. Vitamin C (VitC) is a critical co-factor for Ten-Eleven-Translocation (TET) DNA demethylases, but the impact of its deficiency on embryonic development has gone largely unappreciated. Here, we show that maternal VitC deficiency in L-gulonolactone oxidase ()-deficient mice, which like humans are unable to synthesize VitC, can cause highly penetrant developmental delays and malformations in non-inbred embryos during the vulnerable period of gastrulation. DNA hypermethylation in embryonic neural tissues of susceptible strains increases with VitC dose reduction and with the severity of embryonic pathologies, coinciding with hallmarks of TET1 dysfunction. A moderate reduction in VitC status is sufficient to induce DNA hypermethylation and cause neural tube defects. Our results suggest that promoting timely VitC supplementation by at-risk pregnant mothers may prevent a range of birth defects and enhance health outcomes of future generations.