内脏异位是胚胎左右不对称发育异常引起的多系统畸形，常合并复杂先心病，其发生机制远未阐明。本课题组前期对无已知致病性基因突变及拷贝数变异的内脏异位合并复杂先心病患儿进行全外显子测序发现CCDC141罕见变异显著多于正常对照，且表达于斑马鱼胚胎Kupffer's囊泡（KV），MO抑制其表达后出现心管环化和关键信号分子Nodal表达模式异常，推测CCDC141通过Nodal调控左右不对称发育，是内脏异位新的候选基因。为阐明其机制，本课题拟建立ccdc141敲除斑马鱼模型，观察表型、检测KV纤毛结构与功能、分析相关信号通路、研究互作蛋白明确其调控左右轴发育的机制；并分析患儿CCDC141突变体蛋白功能及其在疾病发生中的作用。本项目从分子、细胞、动物等水平阐述CCDC141的作用机制，将拓宽对左右不对称发育和内脏异位合并复杂先心病发生机制的认识，为内脏异位和相关先心病的早期诊断、遗传咨询提供基础。

Heterotaxy (HTX) syndrome, often complicated with complex congenital heart defects, is a serious multi-system malformation. It is caused by the failure to establish normal left-right asymmetry during embryogenesis, but the underlying pathogenesis of which is far from being elucidated..In HTX patients with complex congenital heart defects that cannot be explained by known causal gene mutation or pathogenic copy number variation, our previous research has revealed that the amount of rare variants of CCDC141 was significantly higher than that in the control group by Exome sequencing. We also found that ccdc141 was expressed in the Kupffer's vesicles (KV) of Zebrafish. Downregulation of ccdc141 by morpholino(MO) in zebrafish resulted in disruption of cardiac looping and abnormal expression of Nodal, the key signaling molecular of left-right patterning. Thus, we hypothesized that CCDC141 maybe a new HTX candidate gene that regulates the development of left-right asymmetry via Nodal signaling..This research aims to elucidate the underlying mechanisms of CCDC141 in left-right patterning. Ccdc141 knock-out Zebrafish model will be constructed and the following experiments will be performed: ① Observe the phenotypes related to left-right asymmetry in Zebrafish models; ② Detect the structure and function of cilia in KV; ③Analyze the signaling pathway; ④Identify the proteins that interact with ccdc141. Moreover，we will analyze the function of CCDC141 mutants of HTX patients and their roles in HTX patients with complex congenital heart defects..Our project will elucidate the mechanisms of CCDC141 on the molecular, cellular, and animal levels. This research will deepen our understandings of the mechanisms of the left-right asymmetry establishment and pathogenesis of HTX patients with complex congenital heart defects, and provide the basis for early diagnosis, genetic counseling, and treatment of HTX and congenital heart defects.