Association Of Metabolites And Gene Polymorphisms In The Folate Pathway With Neural Tube Defects

Objective Neural tube defects are a group of severe birth defect of central nervous system,resulting from the failure of neural tube closure in early embryogenesis.The etiology of NTDs are involved in environmental,metabolism,genetic,and epigenetic factors,and the mechanism is unclear.It's confirmed that the supplementation of folic acid in early pregnancy can reduced the rate of NTDs occurrence.Therefore,we conducted the study of the association of metabolite and gene polymorphism in the folate pathway with neural tube defects in Han population of Northern China,we aimed at understanding that:1.The association of metabolite(Hcy,SAM,SAH)in the folate pathway with NTDs in Han population of Northern China.2.The association of single nucleotide polymorphisms of key enzyme genes in the folate pathway with NTDs in Han population of Northern China.3.The correlation of gene-gene interaction of key enzyme with NTDs in Han population of Northern China.4.The relationship of gene haplotype in folate pathway with NTDs in Han population of Northern China.Methods1.A case-control was conducted in 152 NTDs child patients(61 of them were nuclear families,namely,trios)and 169 healthy children(61 of them were trios.)2.Several biomarkers of folate metabolism were detected and compared between the two groups(122 nuclear families).The best diagnostic values of maternal biomarkers were analyzed by ROC curve.3.The SNPs sites of key genes(BHMT,MTHFD1,MTHFR,MTR,MTRR,RFC1,SHMT1 and TYMS)were retrieved and selected from Hap Map Database using Haploview software.4.Fifty-two SNPs sites were genotyped using sequenom Mass ARRAY system.5.SPSS 19.0 software was used to evaluate the correlation analysis.SHEsis software was used to evaluate the haplotype analysis.PLINK software was used to analyze gene-gene interaction.SIFT and Polyphen were used to predict the influence of mutations on protein function.Results1.The level of maternal folate,SAM and SAM/SAH were lower compared to controls.However,the level of Hcy and SAH were higher than controls,the differences of these markers expect for Hcy were statistically significant(P<0.05).2.The differences of folate biomarkers between the two groups of children were significance,expect for folate(P<0.05).3.The differences of paternal biomarkers expect for Hcy between the case and control group were not significant statistically(P>0.05).4.ROC curve analysis indicated that the area under the curve of SAM/SAH was the biggest(0.98),so was the Youden index(0.64);Then,it followed by SAH,folate,SAM,the above biomarkers were statistical significance.The area under the curve and Youden index of Hcy were the smallest(0.578,0.21)and showed no significance.The best boundary to detect folate,SAM,SAH and SAM/SAH was8.55,51.25,1.45,4.65,respectively.5.The case-control study of 52 SNPs in 8 genes was analyzed.In children,we found that BHMT gene rs3733890,MTHFD1 gene rs2236224/rs2236225,MTHFR gene rs1801133,MTR gene rs1805087,MTRR gene rs10380/rs162036/rs1801394/rs 9332,RFC1 gene rs1051266/rs3788200 and TYMS gene rs502396 were related to the occurrence of NTDs.6.In mother,we found that MTHFD1 rs2236225,MTHFR gene rs1801133,MTRR gene rs1801394,RFC1 gene rs1051266 were related to the occurrence of NTDs in offspring.7.Paternal MTHFR gene rs1801133 and MTRR gene rs1801394 were correlated with NTDs occurrence in offspring.8.Haplotype analysis of NTDs children showed that BHMT gene haplotype C-A-A-A,MTHFD1 gene block1 haplotype A-A/block2 T-A,MTHFR gene haplotype A-G-G-C-T,RFC1 gene haplotype G-G-G-T might be related to the increased risk of NTDs;BHMT gene haplotype C-G-A-A,MTHFD1 gene haplotype C-A in block2,MTR gene haplotype G-G-C-A might be related to the decreased risk of NTDs occurrence.9.Interaction analysis showed the gene-gene interaction between BHMT,MTHFD1,MTHFR,MTR,MTRR,RFC1 and TYMS might be related to the risk of NTDs.Conclusions1.The reduction of folate,SAM,SAM/SAH(DNA methylation index)and the increase of Hcy,SAH may increase the risk of NTDs in maternal and children's maker level in Han population of Northern China.2.Maternal SAM/SAH(DNA methylation index)was valuable on the diagnosis.Followed by the further study with more samples,it could be considered to screen and evaluate the biomarkers of NTDs.3.The polymorphisms of BHMT gene rs3733890,MTHFD1 gene rs2236224/rs2236225,MTHFR gene rs1801133,MTR gene rs1805087,MTRR gene rs10380/rs162036/rs1801394/rs9332,RFC1 gene rs1051266/rs3788200 and TYMS gene rs502396 increased the risk of NTDs in Chinese Han population children;The polymorphisms of maternal MTHFD1 gene rs2236225,MTHFR gene rs1801133,MTRR gene rs1801394,RFC1 gene rs1051266 increased the risk of NTDs in offspring in Han population of Northern China;The polymorphisms of paternal MTHFR gene rs1801133,MTRR gene rs1801394 increased the risk of NTDs in offspring in Han population of Northern China.4.In Han population of Northern China,gene-gene interaction of BHMT,MTHFD1,MTHFR,MTR,MTRR,RFC1 and TYMS could increase the risk of NTDs.5.In Han population of Northern China,BHMT gene haplotype C-A-A-A,MTHFD1 gene haplotype block1 A-A/block2 T-A,MTHFR gene haplotype A-G-G-C-T,RFC1 gene haplotype G-G-G-T could increase the risk of NTDs;However,BHMT gene haplotype C-G-A-A,MTHFD1 gene haplotype block2C-A,MTR gene haplotype G-G-C-A could decrease the risk of NTDs.