MTHFR and Abnormal cardiac septum morphology: Moreover, our results revealed that the values of LINE-1 DNA methylation in DS-CHD+ mothers, as well as in the mothers of children with DS and septal defects, were clearly stratified according to the MTHFR C677T genotype/diet combination: the lowest values were observed in mothers with the CT+TT genotype and a low-folate diet, and the highest levels were observed in mothers with the CC genotype and a folate-rich diet.