ABSTRACT
Objective To investigate the relationship between the methylation level of transcription starts site (TSS) upper stream of homeobox gene and the neural tube defects (NTDs). Methods A case-control study of two stages was designed. In the first stage,10 cases and 8 controls were extracted,in whom Illumina Infinium Human Methylation 450 k genome-wide beadchip was used for the quantification of DNA methylation levels of brain and spinal tissue. In the second stage,differentially methylated region within HOXA5 gene was detected with a larger numbers of samples (52 cases and 23 controls). DNA of brain or spinal tissue was extracted,and Matrix-assisted laser desorption ionization time-of-flight mass spectrometry technique of MassARRAY platform was employed for the validation of differentially methylated region of HOXA5 gene. Results In the first stage,27 CpG sites within TSS region of HOXA5 gene were found to be significantly hyper-methylated in case group compared to control group (P<0.05). In the second stage,a total of 10 CpG sites were analyzable within the differentially methylated region in the first stage. In the NTD case group,spinal bifida subgroup,and anencephaly subgroup,there were 7,6,and 2 sites with significantly higher methylation levels than that of control group (P<0.05). The average methylation level of TSS upper stream region within HOXA5 gene was higher in case group than control group [case group:(31.3±13.9)%,control group:(21.4±9.7)%],and the odds ratio after adjusting gender of fetus and pregnant week was 1.09 (1.03-1.16). Conclusion Hypermethylation within TSS upper stream region of HOXA5 gene in fetus is associated with a higher risk of NTDs.