Molecular characterization of congenital cataract

描述(申请人提供)：每10,000名新生儿中有1-15名患上儿童白内障。先天性白内障是最严重的一种，因为它干扰了正常的视觉发育，并有可能导致永久性失明。遗传学研究已经确定了与各种形式的白内障相关的许多基因的突变。这些已知基因在先天性/青少年白内障患者中的确切突变频率尚不清楚，许多病例仍在等待分子诊断。全外显子组测序(WES)是一种新的技术，可用于识别已知和新基因的致病突变，从而在分子水平上显著促进儿童白内障的特征/分类。在初步实验中，使用WES筛选了22个家族性遗传性先天性/幼年性白内障家系的先证者，并在45%(10/22)的家系中发现了已知的白内障基因和一个新的晶体蛋白基因的致病突变。在这项建议中，我们通过对家族性病例的分析，着重于识别与人类先天性/青少年白内障有关的新的遗传因素。第一个目标是确定与白内障相关的基因突变。 在先前确认的12个没有已知白内障基因突变的家系中，以及另外12个受影响的家系中。第一步将是对额外的先证者进行完整的外显子组测序/已知的白内障基因分析，这可能会在40%-50%的家系中识别致病突变。在没有突变的家族中发现新的遗传因素将首先通过评估在脊椎动物晶状体发育/功能中具有已知作用的基因或位于先前报道的白内障基因座上来实现。下一步，将对突变阴性家系中其他家庭成员的WES及其外显子变异进行联合分析，以识别新因子中的有害变异。第二个目的是通过对斑马鱼中新的候选白内障因素的功能分析，以及对更多患有白内障和相关眼部疾病的人类患者进行这些基因突变的检查，来验证新因素与先天性/青少年白内障的关系。识别与儿童白内障相关的基因/突变等位基因，并确定它们对疾病的具体贡献，将指导开发和利用基因测试，以准确诊断和预测表型严重程度和复发风险，从而为受影响的家庭提供更好的咨询。此外，了解白内障的遗传机制将提高我们对晶状体生物学的知识，并有助于更好地治疗和管理所有年龄段的晶状体混浊。

DESCRIPTION (provided by applicant): Pediatric cataracts are observed in 1-15 per 10,000 births. Congenital cataract represents the most severe end of the spectrum due to interference with normal visual development and the possibility of permanent blindness. Genetic studies have identified mutations in numerous genes associated with various forms of cataracts. The exact frequencies of mutations in these known genes in patients with congenital/juvenile cataract are not known and many cases are still awaiting molecular diagnosis. Whole exome sequencing (WES) is a novel technology that can be utilized for identification of causative mutations in both known and novel genes and thus could significantly facilitate characterization/classification of pediatric cataracts at a molecular level. In preliminary experiments, WES was used to screen probands from 22 pedigrees affected with familial dominant congenital/juvenile cataract and identified causative mutations in known cataract genes and one novel crystallin gene in 45% (10/22) of families. In this proposal, we focus on the identification of novel genetic factors involved in human congenital/juvenile cataract through analysis of familial cases. The first aim is to identify genetic mutations associated with cataract in the twelve previously identified families without mutations in known cataract genes and twelve additional affected pedigrees. The first step will be whole exome sequencing/known cataract gene analysis of the additional probands, which is likely to identify causative mutations in 40-50% of the families. Discovery of novel genetic factors in families without mutations will initiall be approached by evaluation of genes which have a known role in vertebrate lens development/function or are located within a previously reported cataract loci. Next, WES of additional family members in mutation-negative pedigrees and combined analysis of their exome variation will be undertaken to identify deleterious variants in novel factors. The second aim is to verify the involvement of novel factors in congenital/juvenile cataract by functional analysis of the new candidate cataract factors in zebrafish and examination of a larger group of human patients affected with cataract and related ocular conditions for mutations in these genes. Identification of the genes/mutant alleles associated with pediatric cataract and determination of their specific contributions to disease will guide development and utilization of genetic tests for accurate diagnosis and predictions of phenotypic severity and recurrence risks, thus offering superior counseling to affected families. In addition to this, understanding of the genetic mechanisms of cataracts will improve our knowledge about lens biology and lead to better treatment and management of lens opacities at all ages.