[A case-control study on the risk factors of neural tube defects in Shanxi province]

To explore the risk factors of neural tube defects (NTDs) in Shanxi province where the incidence of NTDs had been the highest in China.

1:1 matched case-control study was used. All the objects collected from hospitals were investigated in standardized questionnaires about susceptible risk factors for NTDs and were genotyped for methylenetetrahydrofolate reductase (MTHFR) C667T polymorphism by PCR-RFLP method. The risk factors of NTDs were analyzed by conditional logistic regression and by SPSS 11.5 statistical software. We also analyzed the univariable and multi-variables in order to independently investigate the MTHFR genotype and maternal periconceptional adverse factors influencing on NTDs.

Comparing MTHFR gene frequency between case group and control group, our results showed that three genotypes were found in MTHFR C677T. There was significant difference between two groups at 0.01 level (chi2 = 14.61, P = 0.001) about the three genotypes. The MTHFR T allele frequency of mother with NTDs (60.6%) was higher than that of the control (41.4%), and there was significant difference between them (chi2 = 14.59, P < 0.001). By univariate conditional logistic regression analysis, it was indicated that 15 factors were correlated with NTDs (P < 0.05) in the level alpha = 0.05. By multi-variables conditional logistic regression analysis, four factors were connected to NTDs: frequency of pregnancy (OR = 2.87, 95%CI: 1.28 - 6.44), contacting chemical combination in early pregnancy (OR = 16.18, 95%CI: 1.18 - 221.59), frequent taking of germinated potato (OR = 4.66, 95%CI: 1.78 - 12.17) and MTHFR C677T mutation (OR = 2.13, 95%CI: 1.08 - 4.21).

Factors as 'frequency of pregnancy', 'history of contacting chemicals', 'taking germinated potatoes in early pregnancy', as well as 'MTHFR C677T mutation' in mothers were important risk factors affecting the occurrence of NTDs in Shanxi province.