基于核心家系的全外显子测序鉴定遗传性多发性骨软骨瘤新致病基因

One of the most common hereditary skeletal dysplasias, hereditary multiple exostoses (HME), is an autosomal dominant disorder characterized by the growth of cartilage-capped benign bone tumours around areas of active bone growth. A person with HME has an increased risk of developing a rare form of bone cancer called chondrosarcoma as an adult. In a previous study we developed a method to detect known pathogenic gene (EXT1、EXT2) mutations in HME, and successfully used this in clinical genetic testing. However, these mutations were not detected in approximately 9% (4/45) pedigrees with HME. The results suggested that unknown novel pathogenic gene(s) may be associated with HME. In this study, we will select HME pedigrees with negative EXT1 and EXT2 mutations. We intend to capture and sequence all the coding regions with Agilent SureSelect Human All Exon Kit and Illumina Hiseq sequencing platform. Sequencing data will be analyzed using NextGENe, GATK software and a variety of bioinformatic programs will be used to evaluate the functional significance of identified variants, followed by evaluation of clinical significance according to the phenotypes of family members. The potential list of novel HME genes will be further verified in the other family members and 200 controls, hoping to eventually identify true novel pathogenic gene(s) for HME. The finding of this project may lead to the discovery of new genetic biomarker(s) and help to further improve the genetic diagnosis of HME. These results will provide the experimental basis for molecular diagnosis and genetic counseling in HME, and establish the foundation for clarify the molecular pathogenesis of HME and the development of new therapeutic drugs.

遗传性多发性骨软骨瘤（HME）是一种常染色体显性遗传性骨骼发育异常疾病，属于良性骨肿瘤，但部分患者可恶变为软骨肉瘤。课题组前期建立了已知致病基因EXT1、EXT2的基因突变筛查方法，并成功应用于临床检测。但仍约有9%（4/45）的HME家系在已知致病基因中未找到病理性基因突变位点，提示可能存在新的致病基因。本项目拟以EXT1、EXT2基因突变筛查阴性的HME家系为研究对象，利用序列捕获技术将全基因组外显子区域DNA捕捉、富集后运用Illumina Hiseq测序平台进行高通量测序，并采用基于核心家系的生物信息学分析方法发掘和鉴定新致病基因。从而发现新的检测靶点，进一步完善HME的基因诊断方法。本研究将为HME的分子诊断和遗传咨询提供实验依据，并为进一步阐明分子发病机制及治疗药物的研发奠定基础。

遗传性多发性骨软骨瘤（HME）是一种常染色体显性遗传性骨骼发育异常疾病，属于良性骨肿瘤，但部分患者可恶变为软骨肉瘤。课题组前期建立了已知致病基因EXT1、EXT2的基因突变筛查方法，并成功应用于临床检测。但仍约有9%（4/45）的HME家系在已知致病基因中未找到病理性基因突变位点，提示可能存在新的致病基因。. 本研究项目以EXT1、EXT2基因突变筛查阴性的HME家系为研究对象，利用Agilent Sureselect ExomeV4序列捕获技术将全基因组外显子区域DNA捕捉、富集后运用Illumina Hiseq2500测序平台进行高通量测序，并采用基于核心家系的生物信息学分析方法发掘和鉴定新致病基因。. 我们的研究工作成功地利用全外显子组测序在3个EXT1/EXT2突变阴性的HME家系中鉴定了一个新的与HME相关的候选致病基因TBXAS1基因。TBXAS1基因在成骨细胞、破骨细胞及软骨细胞均有表达，其突变可抑制成熟破骨细胞的生成进而导致骨密度增加。体外功能实验结果表明在斑马鱼中下调Tbxas1基因表达后可导致其软骨细胞形态和排列异常，这些提示TBXAS1基因参与软骨的发育进程。. 本研究发现了HME新的检测靶点，并进一步完善HME的基因诊断方法。本研究结果为HME的分子诊断和遗传咨询提供了更充分的实验依据，并为进一步阐明分子发病机制及治疗药物的研发奠定基础。