Molecular Genetics of high Myopia

描述（由申请人提供）： 摘要近视或近视是一种视觉疾病，其极端形式使个体易患致盲疾病，如视网膜脱离、青光眼、早发性白内障和退行性黄斑病变。近视的发病机制尚未被精确定义，也没有一致有效的治疗方法。最近的研究确定了罕见的遗传性非综合征型高度近视的致病基因，包括我们自己的研究，至少有3个基因发生了相关突变，每一个发现都阐明了眼睛过度生长的分子机制。为了建立在这条富有成效的调查路线上，我们已经确定并仔细描述了230个家族性极高度近视家庭。该提案的目的是利用这一宝贵而独特的家族资源，系统地鉴定这些家族中一个子集的家族性高度近视的致病基因，将其余家族用作病例或对照，并在全球范围内使用其他协作队列资源进行复制。目前传统的连锁和定位克隆方法的局限性包括它们需要大的、多重的家族。此外，在传统连锁分析中缩小候选区域可能是困难的，这是由于缺乏重组事件的大区域，因此这些区域需要繁琐且漫长的致病突变筛选。强大的新遗传工具可以促进这一筛选过程，并改善较小家庭的变异发现。特别是，高效的全外显子组测序，蛋白质编码基因序列的靶向捕获，在我们的研究中应该特别有用，因为大多数孟德尔疾病是由影响靶基因外显子组的突变引起的。通过将全基因组连锁分析和全外显子组测序相结合，我们正在最大限度地发挥我们家族数据的影响，并加速新的近视突变鉴定。在最近发表的研究中，我们发现了与近视高度相关或引起近视的新基因。在本申请中，我们建议从杜克近视数据集中完成致病基因座的鉴定，然后将我们的表征集中在那些功能未知的基因上。通过添加到近视相关基因的网络中，然后将功能分配给那些未知的基因，我们为了解这种疾病的潜在联系和途径提供了必要的信息。我们的目标是：1）使用靶向测序和/或全外显子组测序与连锁作图来鉴定与家族性高度近视相关的遗传变异，并确定这些新的致病突变在杜克和其他近视数据集中的患病率; 2）表征斑马鱼模型中候选致病突变的功能后果，并进行斑马鱼眼组织与诱导眼生长的人和小鼠模型中眼组织的比较表达研究;和3）对通过屈光不正全基因组关联研究，全外显子组测序，和表达研究，以发展可能影响正视化过程（正常屈光发育）的机制的综合观点。这些努力将显著提高我们对正常眼睛生长信号以及近视和以近视为主要特征的相关疾病的发病机制的理解。此外，我们的发现将揭示为极端和常见近视表型开发定制疗法的新机会。

DESCRIPTION (provided by applicant): ABSTRACT Myopia, or nearsightedness, is a visual condition that predisposes individuals in its extreme forms to blinding disorders such as retinal detachments, glaucoma, premature cataracts, and degenerative maculopathy. Myopia pathogenesis has not been precisely defined and there are no consistent effective treatments. Recent studies identifying causal genes in rare, inherited non-syndromic high-grade myopia, including our own study, have associated mutations in at least 3 genes, and each discovery has clarified molecular mechanisms of exaggerated eye growth. To build on this productive line of inquiry, we have ascertained and carefully characterized 230 families with familial extreme high-grade myopia. The objective of this proposal is to use this valuable and unique family resource to systematically identify causal genes for familial high-grade myopia in a subset of these families, using the remainder as cases or controls as well as using other collaborative cohort resources globally for replication purposes. Limitations of current conventional linkage and positional cloning approaches include their requirement for large, multiplex families. In addition, narrowing candidate areas in traditional linkage analysis can be difficult due to large regions that lack recombination events and hence these regions have required cumbersome and lengthy screening for causative mutations. Powerful new genetic tools can facilitate this screening process and improve variant discovery in smaller families. In particular, efficient whole-exome sequencing, the targeted capture of protein- coding gene sequences, should be particularly useful in our studies, as most Mendelian disorders are caused by mutations affecting exomes of the target gene. By combining genome-wide linkage analysis and whole- exome sequencing, we are maximizing the impact of our family data and accelerating novel myopia mutation identification. In recently published studies, we have identified novel genes highly associated with or causative of myopia. In this application, we propose to complete identification of causative loci from the Duke myopia dataset and then focus our characterization on those genes with unknown functions. By adding to the network of myopia-associated genes, and then assigning functions to those which are unknown, we provide essential information for understanding potential connections and pathways involved in this disease. We aim to: 1) Use targeted sequencing and/or whole-exome sequencing with linkage mapping to identify genetic variants associated with familial high-grade myopia, with prevalence determination in the Duke and other myopia datasets of these new causative mutations; 2) Characterize functional consequences of candidate causative mutations in zebrafish models, and perform comparative expression studies of ocular tissues in zebrafish to that in humans and mouse models of induced eye growth; and 3) Perform convergent gene list enrichment analyses and biological pathway analyses of sets of genes determined by refractive error genome wide association studies, whole exome sequencing, and expression studies to develop an integrated view of the mechanisms that might influence the process of emmetropization (normal refractive development). These efforts will significantly improve our understanding of normal eye growth signals and of the pathogenesis of myopia and related disorders with myopia as a cardinal feature. Moreover, our discoveries will reveal new opportunities to develop customized therapies for extreme and common myopia phenotypes.