Molecular Characterization of Pontocerebellar Hypoplasia

项目总结/摘要 脑桥小脑发育不全（PCH）是一个异质性组，大多数是隐性儿童脑 表现出神经发育受损和存在神经变性的特征的疾病。 PCH的特征是严重的年龄依赖性神经功能损害， 脑桥和小脑体积损失，脑干和小脑神经元损失。目前 在PCH中已知有32个基因突变，但仍有更多的基因有待发现， 机制知之甚少。一些基因涉及蛋白质合成的关键步骤， 基因组完整性，包括tRNA和mRNA剪接，表明破坏稳态细胞 功能，但仍存在许多问题：1）还有多少基因亚型有待发现？二、 为什么广泛表达基因的缺失会使神经元特异性地易感？3]是否存在收敛性 PCH的分子途径在过去的5年里，我们已经：1]发展了我们独特的PCH队伍 患者，包括248个家庭，其中132个仍然没有分子原因。2]应用了一系列 基因组学和转录组学方法来发现几个新基因的突变，包括 TOE 1、TBC 1D 23、PRP 17和PPIL 1导致特异性PCH亚型。3]发现RNA缺陷 剪接和基因组完整性作为根本原因。4]发现了第一个剪接体蛋白 突变。5]揭示了新的基因型表型相关性。在我们的初步数据中，我们有： 确保资源，以推进全基因组测序，以评估我们剩余的未解决的案件。 2]发现了另外10个新的基因作为PCH的原因。3]值得注意的是，发现六本小说 导致编码剪接体蛋白。4]发现R环积累是DNA损伤的原因 突变会导致基因毒性压力该应用程序的目标是：1]确定剩余的 PCH的“可替代”基因。2]在致病框架内功能性验证突变。三、 检验PCH基因缺失通过R环积累导致神经元细胞死亡的假设， DNA损伤和遗传毒性应激。这项工作将导致深入了解的原因和机制， 婴儿脑病重要原因，并揭示选择性神经元 脆弱性和儿童神经变性潜在的发育性脑疾病。

PROJECT SUMMARY/ABSTRACT Pontocerebellar hypoplasia (PCH) is a heterogeneous group of mostly recessive pediatric brain disorders that show features of both impaired neurodevelopment and presence of neurodegeneration. PCH is characterized by severe age-dependent neurological impairment, and notable radiographic volume loss of the pons and cerebellum with loss of brainstem and cerebellar neurons. Currently there are 32 genes known mutated in PCH, but still more genes await to be discovered, and molecular mechanisms are poorly understood. Some of the genes implicate key steps in protein synthesis and genomic integrity including tRNA and mRNA splicing, suggesting disruption to homeostatic cellular functions, but many questions remain: 1] How many genetic subtypes remain to be discovered? 2] Why do loss of broadly expressed genes predispose specifically to neurons? 3] Are there convergent molecular pathways for PCH? Over the past 5 years, we have: 1] Grown our unique cohort of PCH patients, containing 248 families including 132 still without a molecular cause. 2] Applied a range of genomics and transcriptomics methods to uncovered mutations in several novel genes including TOE1, TBC1D23, PRP17 and PPIL1 leading to specific PCH subtypes. 3] Revealed defects in RNA splicing and genome integrity as underlying causes. 4] Uncovered the first spliceosome protein mutations. 5] Revealed new genotype phenotype correlations. In our preliminary data we have: 1] Secured resources to advance whole genome sequencing to evaluate our remaining unsolved cases. 2] Identified a further ten new genes as causes for PCH. 3] Remarkably, found that six of the novel causes encode spliceosome proteins. 4] Uncovered R-loop accumulation as a cause of DNA damage by which mutations lead to genotoxic stress. The goal of this application is to: 1] Identify the remaining ‘discoverable’ genes for PCH. 2] Functionally validate mutations within a pathogenic framework. 3] Test the hypothesis that PCH gene loss leads to neurons cell death through R-loop accumulation, DNA damage and genotoxic stress. This work will lead to insight into causes and mechanisms of an important cause of infantile encephalopathy, and uncover mechanisms of selective neuronal vulnerability and pediatric neurodegeneration underlying developmental brain disease.