SDHD截短突变R38X家族性副神经节瘤表型的影响因素及作用机制研究

Head and neck familial paraganglioma is originated in the neural crest cells ，which is an autosomal dominant genetic disease with high surgical morbidity . The SDHD mutation is the common virulence gene,and the year of symptom with a nonsense mutation SDHD is eight point five years earlier than that with a SDHD missense mutation; plateau mutation has severe symptoms;these same SDHD mutations have different clinical phenotypes，In our previous study of familial paraganglioma in China,the SDHD gene generated truncated body mutation (R38X) in the probands germline ,which induced mitochondrial SDH subunit D translation termination in advance.Analysised the characteristic of the early disease found、severe symptoms and high malignant rate in the highland area resident pedigree,we suggest that the influence factors of the disease phenotype include truncated mutation，which results in lower succinate dehydrogenase activity than missense mutation;The mutated cells produce reactive oxygen molecules, causing genomic instability,then inducing the phenotype diversity; hypoxic environment aggravates the clinical phenotype.To verify this hypothesis,analysising the function of SDHD mutantion from molecular biology level, using experiments in vivo and in vitro,to explore the effect of mutations、hypoxia environmental factors and their interactions in paraganglioma pathogenesis;following up dynamicly and analysising systemly the pedigree influence factors,to further explore the molecular regulatory mechanisms,provide a theoretical basis for the prevention and treatment of paraganglioma.

头颈部家族性副神经节瘤是原发于神经嵴细胞的常染色体显性遗传病，手术治疗致残率高。其常见致病基因SDHD无义突变比错义突变者平均早8.5年发病，且高原突变者症状更为严重；相同SDHD突变的临床表型多变，产生这些现象的机理不明。课题组前期研究了我国副神经节瘤家系，发现先证者种系细胞SDHD发生截短体突变（R38X），致线粒体琥珀酸脱氢酶亚单位D翻译提前终止；分析该家系高原区居民发病早、症状重和恶变率高的特点，推测影响该病表型因素包括：截短突变比错义突变导致更低的琥珀酸脱氢酶活性；突变后细胞内产生活性氧分子，引发基因组不稳定致临床表型多样性；低氧环境加重临床表型。为验证此假说，从分子生物学水平分析SDHD突变体功能，运用体内、外实验探讨突变基因、低氧环境因素及其交互作用在副神经节瘤发病中的作用；动态随访并系统分析家系表型的影响因素，进一步探讨SDHD分子调控机制，为副神经节瘤的防治提供理论依据。

项目背景：头颈部家族性副神经节瘤是原发于神经嵴细胞的常染色体显性遗传病，手术治疗致残率高。其常见致病基因SDHD 无义突变比错义突变者平均早8.5 年发病，且高原突变者症状更为严重；相同SDHD 突变的临床表型多变，产生这些现象的机理不明。课题组从分子生物学水平分析SDHD 突变体功能，运用体内、外实验探讨突变基因、低氧环境因素及其交互作用在副神经节瘤发病中的作用；动态随访并系统分析家系表型的影响因素，进一步探讨SDHD 分子调控机制，为副神经节瘤的防治提供理论依据。.研究内容：一是在体外细胞水平上对SDHD各突变体的功能开展研究。二是体内实验，运用肿瘤动物模型观察SDHD各突变体对细胞成瘤率和肿瘤生长速度影响。三是对患者的肿瘤相关基因的外显子进行测序，分析其他基因的突变。四是人群验证分析。.重要结果：3年期间经门诊收治的头颈部副神经节瘤患者，术后诊断为颈动脉体瘤患者约60位，其中多发性头颈部副神经节瘤患者21例。对其符合手术指征的患者行手术治疗，留取患者的血标本和组织标本，对其21例多发性副神经节瘤患者及其家属行相关副神经节瘤基因突变检测，突变常发生于SDHD，突变点有c.C242T、c.112C>T及c.188_198del等。发现2例新型突变，分别为位于RET基因的c.3247A>G和位于SDHD基因的c.387_393del7突变。课题组同时行SDHD基因的功能试验，通过病毒包装进行细胞感染等实验。.意义：通过临床与分子生物学相结合，全面认识头颈部副神经节瘤在发病机制、临床治疗等方面的相关内容，逐步制定头颈部多发性副神经节瘤的个体化诊疗方案，同时为探讨分析SDHD 突变体的功能奠定基础。