CTCF and neural tube defect: The results revealed that the DNA methylation level of the CTCF-binding site in H19 DMR1 in the Watson strand was stable in cases and controls; however, a CpG site 33bp away was dramatically hypermethylated from 30.86±1.19% to 49.62±1.62% (P = 2.33e-07, Student's t-test; Fig. 3A), suggesting that H19 DMR1 is hypermethylated in NTD cases.