MTHFR and atrial septal defect: Subtype analysis showed a higher risk for ventricular septal defect (VSD) (OR = 5.67, 95%CI: 3.1-10.0 ), atrial septal defect (ASD) (OR = 9.51, 95%CI: 4.9-18.4), and patent ductus arteriosus (PDA) (OR=15.52, 95%CI: 7.1-33.7) for MTHFR c.677C>T, while MTRR c.66A>Gwas associated with ASD (OR = 8.67, 95%CI: 4.9-15.0) and PDA (OR = 18.54, 95%CI:9.3-36.9).