本课题组收集一个常染色体显性非综合征遗传性耳聋大家系SH，已将该家系致聋基因定位在常染色体18p11.3区域（最大LOD值4.93），候选区域位于rs4797697与rs11080868之间，约1.4Mb大小,该区域不包含已知耳聋基因；全基因组外显子测序联合连锁定位，发现了一个耳聋新致病基因及其突变位点:THOC1（NM_005131),c.C547G,p.L183V; 后续经直接测序证实该突变位点在SH家系中共分离；前期功能实验已证实THOC1蛋白表达于小鼠内耳的外毛细胞和内毛细胞；同时发现THOC1在斑马鱼神经丘的毛细胞中特异性的表达。接着我们建立了THOC1敲除与敲低的斑马鱼模型，发现THOC1缺失可以导致斑马鱼毛细胞的个数显著减少，促进斑马鱼神经丘中毛细胞异常的凋亡。我们拟构建THOC1p.L183V基因敲入小鼠模型，对THOC1及其突变进行深入的听觉功能研究，探索其具体发病机制。

In a dominant family segregated with late-onset, progressive, non-syndromic hearing impairment, linkage analysis revealed a 1.4Mb candidate region on chromosome 18p11.3 that contains THOC1. Whole-exome sequencing identified a heterozygous p.L183V variant of THOC1 as the only candidate mutation segregating with the hearing loss within the family. Antibody immunostaining analysis showed THOC1 was highly expressed in mouse hair cells. Consistently, we observed that thoc1 was specifically expressed in the zebrafish developing neuromasts, particularly enriched in the hair cells. In the thoc1 mutants and morphants, the hair cell number in each neuromast and in the whole embryo is dramatically decreased. In addition, both human THOC1 mRNA and zebrafish thoc1 mRNA significantly rescued the hair cell defects caused by loss of Thoc1. While the mutated THOC1 (p.L183V) mRNAs showed remarkable less capacity to restore the hair cell defects. Furthermore we demonstrated that thoc1 deficiency induced hair cell apoptosis. In this study, knock-in mouse will be generated for functional studies of the causative gene THOC1 of nonsyndromic deafness. In addition, several type of technologies, including: biochemical analysis, molecular biological analysis, electrophysiological analysis, live imaging, etc., will be employed to elucidate the complex mechanism of the novel deafness THOC1caused by identified gene mutations. The studies in this project will increase our knowledge of the molecular bases of nonsyndromic hereditary hearing loss, and provide new opportunities for the diagnosis and treatment of this disease in the hearing loss population.