Abstract: With birth mortality decreasing significantly，birth defects have become more serious in China. Increasing evidences supported the polymorphisms of genes involved in the folate metabolic pathway impact the occurrence of birth defects. MTHFR 677C＞T polymorphism impacting the occurrence of neural tube defects had reached a consistent conclusion. However，the relationship between MTHFR 677C＞T, MTHFR 1298A＞C and cleft lip/palate，congenital heart disease，Down′s syndrome is still controversial. Researches seldom took further study on the correlation between MTR 2756A＞G，MTRR 66A＞G，RFC-1 80A＞G polymorphism and birth defects. In this summary，we outlined the origination of folate，metabolic pathway and the association between the polymorphisms of genes involved in the pathway and birth defects.

Key words: Folic acid, Polymorphism, single nucleotide, Congenital abnormalities