维甲酸（RA）信号异常通路可导致神经管畸形（NTDs）发生，胚胎中枢神经系统RA水平和分布受其降解酶CYP26的精确控制。人CYP26B1基因的纯合点突变和杂合缺失可引起颅面部畸形，我们前期大样本高通量测序发现CYP26B1基因变异富集于NTDs样本（病例 vs. 对照 9∶0），其中一个变异位于剪接区, 这些变异是否引起NTDs，机制如何？为探索该基因变异是否通过RA信号通路异常导致NTDs发生，本课题拟采用人NTDs脑组织样本和CYP26B1错义突变转染的小鼠神经干细胞，检测分析CYP26B1基因表达、RA代谢水平及RA受体表达；通过ChIP-Seq、RNA-Seq方法，在构建的突变体中筛选被RA异常调控的与神经管发育直接相关的靶基因，并在突变携带者中验证，以揭示CYP26B1基因变异导致NTDs的分子机制，为进一步阐明罕见变异导致NTDs发生提供实验依据。

Retinoic acid (RA) is a known teratogen of Neural tube defects (NTDs). Its distribution and levels in developing central nervous system are precisely controlled by the degradative enzymes of the cytochrome P450 subfamily (CYP 26). It has been reported that CYP26B1 gene haploinsufficiency or homozygous mutation in human cause lethality, craniofacial abnormalities. Our preliminary finding from high-though target sequencing indicates that single nuclide variant of CYP26B1 significantly attacked in NTDs compared with the matched controls (case vs. control: 9:0). To study whether NTDs pathogenesis induced by CYP26B1 mutations through RA dysregualtion, we will detect the expression level of CYP26B1, RA and its receptors by human brain tissues and mouse neural stem cells carrying missense mutation found in human cases. Furthermore, using ChIP-Seq, RNA-Seq et al. methods, the changes in RA receptors regulated candidate genes which are crucial for neural tube closing will be explored. Subsequently, the screening profile of changes will be validated in human samples. It is respected that the study will explain the pathogenic mechanism of rare genetic variant of CYP26B1 in the aspect of dysregualtion of RA pathways, further display the experimental evidence in heritable etiology of NTDs.