MTHFD1 and ventricular septal defect: Additionally, the genetic polymorphisms of maternal MTHFD1 gene at rs2236222 were significantly associated with a higher risk of VSD in offspring (GG vs. AA: aOR = 2.75, 95%CI: 1.57–4.83; the dominant model: aOR = 1.44, 95%CI: 1.09–1.90; the recessive model: aOR = 2.52, 95%CI: 1.45–4.38; the additive model: aOR = 1.46, 95%CI: 1.17–1.82).