Analysis on the correlation between MTHFR C677T polymorphisms,homocysteine level and fetal congenital heart disease

Objective To assess the relationship between the MTHFR 677 TT genotype, homocysteine (Hcy) level and the risk of fetal congenital heart disease (CHD).Methods From June 2013 to August 2016, 160 healthy pregnant women (single pregnancy) receiving regular prenatal examination in Henan Maternal and Child Health Care Hospital were selected and divided into case group (60 pregnant women with CHD fetuses) and control group (120 pregnant women with normal fetuses). Both the groups were asked about the folic acid supplementation before and during pregnancy. The genotype of folate metabolizing enzyme MTHFRC677 T in oral mucosa and the concentration of homocysteine in plasma were measured. The relationship between different genotypes of MTHFRC677 T and plasma homocysteine and fetal congenital heart disease was compared.Results MTHFRC677 T gene polymorphism was associated with fetal congenital heart disease. The genotype of MTHFRTT in CHD group was higher than that in control group (χ²= 9.4, P=0.002).The genotype of MTHFRCC in control group was higher than that in CHD group (χ²= 9.97, P=0.002). The frequency of T allele in CHD group was higher than that in control group (χ²= 15.7, P<0.05). Compared with homozygous CC genotype, the risk of CHD in homozygous CT genotype and in TT genotype were 2.541 times (95%CI: 1.113-5.803, P=0.024) and 5 times (OR=5.257, 95%CI: 2.133-12.960, P=0.000) higher than that in homozygous CC genotype (95%CI: 1.113-5.803, P=0.024); the risk of CHD in both CT and TT genotype was higher (OR=5.257, 95%CI: 1.542-7.206). The risk of T gene mutation associated with CHD is about 2.5 times higher than that of wild type allele C gene mutation associated with CHD. (OR=2.455, 95%CI: 1.567-3.847, P=0.000). In CT genotype and TT genotype group, the level of Hcy in blood was higher than that of CC genotype, and the difference was statistically significant. The blood Hcy level in the TT genotype group was higher than that in the CT genotype group, and the difference was statistically significant. The average blood Hcy7.12 + 1.47 umol/L in CHD group was higher than that in control group, and the difference was statistically significant (P<0.01).Conclusion MTHFR gene polymorphism, a key enzyme in folate metabolism, has an important effect on the occurrence of fetal congenital heart disease and is a genetic predisposing factor for the occurrence of fetal congenital heart disease, and Carrying mutation allele will increase blood Hcy level and increase the risk of fetal congenital heart disease.