Modifiers of Retinal Phenotypes in Ciliopathies

纤毛病视网膜表型的修饰因素

• 批准号: 8918623
• 负责人: Erica Ellen Davis
• 金额: $ 37.95万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8918623
• 关键词: Adult; Affect; Alleles; Animals; Architecture; Biogenesis; Biological Assay; Blindness; Cilia; Clinical; Collection; Computer Simulation; Cystic Kidney Diseases; DNA Resequencing; Data; Databases; Defect; Development; Diagnosis; Disease; Dissection; Electroretinography; Engineering; Frequencies; Functional disorder; Genes; Genetic; Genetic Epistasis; Genotype; Guanosine Triphosphate Phosphohydrolases; Hereditary Disease; Human; Human Genetics; In Vitro; Individual; Joubert syndrome; Knock-in Mouse; Lead; Leber' s amaurosis; Lesion; Link; Medical; Modeling; Modification; Mus; Mutate; Mutation; Nature; Neonatal; Organelles; Patients; Penetrance; Phenotype; Photoreceptors; Play; Population; Proteins; Proteome; Reporter; Retina; Retinal; Retinal Degeneration; Retinitis Pigmentosa; Role; Sensitivity and Specificity; Severities; Signal Transduction; Site; Structure; Syndrome; System; Testing; Therapeutic; Variant; base; ciliopathy; cohort; early onset; empowered; genetic information; improved; in vitro Assay; in vivo; interdisciplinary approach; mouse model; mutant; novel; outcome forecast; photoreceptor degeneration; pleiotropism; protein transport; tool

Genetic lesions affecting ciliary structure and function give rise to a broad collection of genetically heterogeneous and clinically overlapping disorders, known collectively as the ciliopathies, which are characterized by both phenotypic overlap and variable penetrance and expressivity. In the retina, a modified cilium plays an integral role in protein transport across the photoreceptor and is critical for retinal architecture and function, as evidenced by the fact that progressive photoreceptor degeneration is a hallmark of numerous ciliopathies. Accumulating evidence suggests that genes mutated in some ciliopathies can contribute both causal and modifying alleles across the ciliopathy spectrum, giving rise to the idea that both cis and trans acting alleles can contribute to the mutational load of ciliopathy patients and offer the possibility that understanding the genetic architecture of ciliopathies might inform the mechanisms that underlie phenotypic variability in human genetic disorders. To explore this notion, we have previously conducted unbiased medical resequencing of genes known/expected to be important to ciliary biogenesis and function in a large, clinically diverse cohort of patients that span the spectrum of severity. In RPGRIP1L, a gene known to cause neonatal lethal Meckel-Gruber Syndrome (MKS) and moderately severe Joubert Syndrome (JBTS), we identified a highly-conserved A229T change which was present at intermediate population frequency, and was significantly enriched in patients with retinal degeneration. Using an interdisciplinary approach, we went on to show that the Thr229 allele is a non-neutral change that disrupts the direct interaction between RPGRIP1L and RPGR, the most frequent genetic cause of X-linked Retinitis Pigmentosa (XLRP). These data offer us the opportunity explore the genetic mechanism(s) of second-site modification in retinal phenotypes in ciliopathies, and to develop models that can be used to probe such phenomena further. We propose two aims. First, motivated by the opportunity to develop a robust model to study epistasis, we will model the A229T change by introducing it into a mouse model and subsequently crossing the Thr229 allele into lines with sensitized ciliary function to determine if this allele will either induce or exacerbate retinal phenotypes. Second, because our preliminary data suggest that RPGRIP1L might also contribute epistatic alleles to non-syndromic retinal degeneration, we will expand the mutational analysis of RPGRIP1L to an extended cohort of non-syndromic patients and matched controls. Using our previously established in vivo complementation strategy, we will then test the pathogenic potential of newly discovered alleles, and, empowered with functional data, we will determine the overall enrichment of RPGRIP1L alleles in retinal degeneration. The completion of our studies will identify candidate modifier alleles in patients with retinal degeneration, generate new models to study such phenomena and has the potential to inform the genetic basis of phenotypic variability, which in turn will contribute to the better diagnosis and long-term management of patients.

影响纤毛结构和功能的遗传病变导致广泛的遗传 异质性和临床重叠的疾病，统称为纤毛病， 其特征是表型重叠以及可变的外显率和表达率。在视网膜中，经过修饰的 纤毛在跨光感受器的蛋白质运输中发挥着不可或缺的作用，并且对于视网膜结构至关重要 进行性感光细胞退化是许多疾病的一个标志，这一事实证明了这一点 纤毛病。越来越多的证据表明，某些纤毛病中的基因突变可能导致这两种疾病 整个纤毛病谱中的因果和修饰等位基因，产生了顺式和反式的想法 作用等位基因可能会增加纤毛病患者的突变负荷，并提供以下可能性： 了解纤毛病的遗传结构可能会揭示表型背后的机制 人类遗传疾病的变异性。为了探索这个概念，我们之前进行了公正的医学研究 对大型临床中已知/预期对纤毛生物发生和功能重要的基因进行重新测序 不同严重程度的患者群体。在 RPGRIP1L 中，一种已知会导致新生儿 致命的梅克尔-格鲁伯综合症 (MKS) 和中度严重的朱伯特综合症 (JBTS)，我们确定了 高度保守的 A229T 变化以中等群体频率存在，并且显着 视网膜变性患者中含量丰富。使用跨学科的方法，我们继续证明 Thr229 等位基因是一个非中性变化，破坏了 RPGRIP1L 和 RPGR 之间的直接相互作用， X 连锁色素性视网膜炎 (XLRP) 的最常见遗传原因。这些数据为我们提供了机会 探索纤毛病视网膜表型第二位点修饰的遗传机制，并 开发可用于进一步探讨此类现象的模型。我们提出两个目标。首先，动机是 有机会开发一个强大的模型来研究上位性，我们将通过引入它来模拟 A229T 的变化 进入小鼠模型，随后将 Thr229 等位基因杂交到具有敏化纤毛功能的品系中，以 确定该等位基因是否会诱导或加剧视网膜表型。其次，因为我们的初步 数据表明 RPGRIP1L 也可能导致非综合征性视网膜变性的上位等位基因，我们 将把 RPGRIP1L 的突变分析扩展到非综合征患者的扩展队列中， 匹配的控件。使用我们之前建立的体内互补策略，我们将测试 新发现的等位基因的致病潜力，并且借助功能数据，我们将确定 视网膜变性中 RPGRIP1L 等位基因的整体富集。完成我们的研究将确定 视网膜变性患者的候选修饰等位基因，生成新模型来研究此类 现象并有可能揭示表型变异的遗传基础，这反过来又将 有助于更好地诊断和患者的长期管理。