遗传性黄斑营养不良致病基因的筛查定位及功能研究

Hereditary macular dystropies (HMDs) consist of a number of severe central retinal degenerative diseases with significant genetic and clinical heterogeneities, which can lead to severe central visual impairments or even blindness. However, the phenotypic overlaps and variability in HMDs often make clinical diagnosis uncertain and complicated. Therefore, a specific molecular diagnosis of HMDs to help clinical diagnosis is imminent. Moreover, the eugenic diagnosis based on the screening of genetic mutation is the most effective preventive measures to reduce the incidence of HMDs and to provide target site for gene therapy. However, identified HMD-causing genes can explain about 40% of patients with HMDs. It severely limits widespread use of genetic diagnosis as a routine clinical testing project due to potentially many unidentified genes. Based on the local rich genetic resources, this study is to identify the novel disease-causing genes in the families with a variety of HMDs by the exome sequencing for extending the disease-causing gene spectrum of HMDs. The protein structure and function of the novel disease-causing gene mutations are evaluated by the optimized bioinformatics analyses system to predict the possible pathogenicity. Meanwhile, the cell and animal models are made for investigating the function and molecular genetics mechanism of the novel gene mutations. Furthermore the relationship of genotype and phenotype is analyzed to improve the level and efficiency of genetic diagnosis. On this basis, we will promote the clinical application of genetic diagnosis and eugenics program as a routine testing project in patients with HMDs.

遗传性黄斑营养不良（HMDs）是一组具有高度遗传和临床异质性的常见致盲性眼病。复杂多样的临床表型及不同HMDs表型之间的相似性和交叉性，给临床诊断带来极大的困惑和不确定性,迫切需要通过基因诊断来提高HMDs的临床诊断水平。而且基于基因突变检测的优生诊断是降低HMDs群体发病率最有效措施及基因治疗前提。然而已知致病基因仅可解释40%左右HMDs的发病，仍有大量的患者致病基因不明，严重制约基因检测在临床常规应用。本课题拟对采用目标序列捕获测序未检测到致病基因突变的HMDs家系，应用全基因组外显子测序筛查新的致病基因，利用蛋白结构和功能分析系统预测其致病性，丰富HMDs致病基因图谱。并制作相应的细胞和动物模型研究新致病基因功能，探讨HMDs的分子遗传学机制。分析HMDs患者的临床特征和基因型的对应关系，提高基因诊断的针对性和可靠性。推进HMDs基因诊断和优生诊断作为常规检测项目在临床的推广应用。

遗传性黄斑营养不良（HMDs）是一组具有高度遗传和临床异质性的致盲性眼病。复杂多样的临床表型及不同HMDs表型之间的相似性和交叉性，给临床诊断带来极大困惑和不确定性，迫切需要通过基因诊断来提高诊断水平。基于基因检测的优生诊断是降低HMDs群体发病率最有效措施及基因治疗前提。然而已知致病基因仅可解释40%左右HMDs的发病，仍有大量患者致病基因不明，严重制约基因检测在临床常规应用。.本课题收集了89个HMDs家系（单纯型和综合征型），包括视锥细胞营养不良（COD）、锥视杆细胞营养不良（CORD）、Stargardt病、Best卵黄样黄斑营养不良（BVRD）、常染色体隐性遗传Best病（ARB）、 成人发病的卵黄样黄斑营养不良（AVRD）、中心性晕轮状脉络膜营养不良、青少年X连锁视网膜劈裂症、全色盲、黄斑缺损、回旋状脉络膜视网膜萎缩家系，Hermansky-Pudlak综合征、Alstrom 综合征、视网膜纤毛病等14类HMDs。采用全基因组外显子测序技术对43个HMD家系进行致病基因突变筛查:（1）在35个HMD家系检测到致病基因突变，涉及13个相关致病基因，检测出36个新的变异。对新发现的突变位点，利用相应的蛋白结构和功能分析系统评价基因突变对蛋白质结构和功能产生的影响。根据ACMG推荐指南进行致病性评估。对确定致病基因的家系成员提供遗传咨询及生育指导。（2）通过基因型和临床表型分析明确基因突变导致的疾病谱，例如ABCA4突变导致COD、CORD、Stargardt病及视网膜色素变性（RP）；CRB1突变导致COD、CORD及Leber先天性黑矇(LCA) ；PROM1突变导致COD、CORD及RP ；BEST1突变的临床表型为BVRD、AVRD，ARB。提高了此类疾病基因诊断的针对性和可靠性。（3）在1个综合征型纤毛病家系发现新致病基因IFT52纯合错义突变，该基因突变导致的眼部临床表型为LCA，既有视锥细胞严重受累的黄斑营养不良，也有视杆细胞受累的临床表现。本研究丰富了HMDs致病基因谱及基因突变导致的遗传性眼病疾病谱，推进了HMDs基因诊断和优生诊断作为常规检测项目在临床的推广应用。