TET1 and neural tube defect: In the B6-Tet1tm1Koh strain, we observed a 25% failure in rostral neuropore closure without developmental delay or other gross abnormalities among Tet1−/− (knockout, KO) embryos, indicating a specific impact on cranial NTC, while no NTD was observed in Tet1+/+ (wild type, WT) and Tet1+/− (heterozygous, HET) littermates (Fig. 1A).