Modifiers of Retinal Phenotypes in Ciliopathies

纤毛病视网膜表型的修饰因素

• 批准号: 8163608
• 负责人: Erica Ellen Davis
• 金额: $ 36.73万
• 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 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8163608
• 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; improved; in vitro Assay; in vivo; interdisciplinary approach; mouse model; mutant; novel; outcome forecast; photoreceptor degeneration; pleiotropism; protein transport; tool

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: Retinal degeneration caused by dysfunction of ciliary proteins represents a frequent cause of both early onset and adult blindness, and the observed clinical variability among affected individuals poses a significant challenge in terms of prognosis and treatment. However, recent characterization of the ciliary proteome and the development of in vivo tools pose a unique opportunity to identify and model modifiers of both penetrance and expressivity in these disorders which in turn, has the potential of enhancing the predictive power of the genotype.

描述（由申请人提供）：影响睫状结构和功能的遗传病变产生了广泛的遗传异质性和临床重叠疾病，统称为纤毛病，这是由表型重叠和可变的渗透性和可变的渗透率和可变性和表现力所表现出来的。在视网膜中，修饰的纤毛在跨光感受器的蛋白质转运中起着不可或缺的作用，对于视网膜结构和功能至关重要，这证明了渐进的光感受器退化是众多纤毛病的标志。积累的证据表明，某些纤毛病中突变的基因可以促进纤毛病谱的因果和修改等位基因，从而产生了这样一个观念，即顺式和跨性别等位基因都可以导致纤毛病患者的突变，并提供理解ciilioppatione的可能性的可能性。疾病。为了探讨这一概念，我们以前已经对已知/期望对睫状生物发生和功能重要的基因进行公正的医学重新取证，在跨越严重程度范围的大型临床群体中，在临床上多样化的患者中。在RPGRIP1L中，一种已知引起新生儿致死性梅克尔 - 梅克尔梅克尔综合征（MK）和中度严重的乔伯特综合征（JBT）的基因，我们鉴定出在中间种群频率下存在高度保存的A229T变化，并且在视网膜退化的患者中显着富集。使用跨学科的方法，我们继续表明THR229等位基因是一种非中性变化，它破坏了RPGRIP1L和RPGR之间的直接相互作用，RPGRIP1L和RPGR是X连锁视网膜炎的色素炎（XLRP）的最常见遗传原因。这些数据为我们提供了机会，探讨了纤毛病变视网膜表型中第二站点修饰的遗传机制，并开发可用于进一步探究这种现象的模型。我们提出了两个目标。首先，以开发出强大模型来研究上毒的机会的动机，我们将通过将其引入小鼠模型并随后将THR229等位基因带入具有灵敏的纤毛函数的线条来确定该等位基因是否会诱导或诱发视网膜表型。其次，由于我们的初步数据表明RPGRIP1L也可能为非同伴视网膜变性造成上皮等位基因，因此我们将将RPGRIP1L的突变分析扩展到扩展的非同伴患者和匹配的对照组。然后，我们将使用先前建立的体内互补策略，然后测试新发现的等位基因的致病潜力，并通过功能数据授权，我们将确定视网膜变性中RPGRIP1L等位基因的总体富集。我们的研究的完成将确定视网膜变性患者的候选修饰剂等位基因，生成新的模型来研究这种现象，并有可能告知表型变异性的遗传基础，这反过来又有助于对患者进行更好的诊断和长期治疗。 公共卫生相关性：由睫状蛋白功能障碍引起的视网膜变性代表了早期发作和成人失明的常​​见原因，并且观察到的受影响个体的临床变异性在预后和治疗方面构成了重大挑战。然而，睫状蛋白质组的最新表征和体内工具的开发构成了独特的机会，可以在这些疾病中识别和建模具有渗透性和表现力的修饰符，这反过来又具有增强基因型的预测能力。