In conclusion, our meta-analysis suggested that the MTRR c.66A>G (rs1801394) polymorphism and MTHFD1 c.1958G>A (rs2236225) were associated with increased maternal risk for DS.
The role of methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) G1958A and betaine-homocysteine methyltransferase (BHMT) G742A polymorphisms in DS risk was investigated.