Mosaicism in focal cortical dysplasias spectrum seen in neuropsychiatric disease

 描述（由申请人提供）：最近发现，CNV和点突变形式的新生合子突变对精神分裂症和自闭症等神经精神疾病有重要作用，这引出了关于新生合子后嵌合突变在多大程度上也对疾病有作用的问题。在这个模型中，合子后发生的突变可以在大脑中播种一定比例的细胞，并且足以导致神经元功能障碍和疾病。仅对非神经组织（如血液）进行测序的方法可能会削弱镶嵌现象的检测，因为突变可能仅限于神经组织。该提案汇集了一个高效协作的团队，其中每个成员都贡献了一个特殊的资源，使这项工作真正独特。Gleeson和Masters最近在发育中的大脑中发现了第一批新生体细胞突变，这种突变被称为“半侧巨脑畸形”（HME），这是一种与局灶性皮质紊乱（FCD）相关的灾难性神经精神疾病。通过比较患病大脑与血液中的DNA，我们鉴定了PIK 3CA，AKT 3和MTOR（mTOR通路的一部分）中的新生体细胞突变，仅占8%的脑细胞，导致整个大脑半球的扰动。Courchesne和Roy最近在大多数自闭症儿童（ASD）研究的脑样本中发现了额叶和颞叶皮质中异常层状细胞结构的局灶性斑块，我们认为类似于FCD的局灶性斑块可能具有类似的突变并导致疾病。本申请的目标是通过在单细胞水平上在DNA和RNA水平上对发育不良与相邻正常组织和/或血液进行测序，来扩展癫痫和自闭症患者中镶嵌现象的发现，其中神经组织病理学证据指向FCD。我们的目标是发现关键的基因组，其中特定的从头突变，在特定的位置，在特定的镶嵌水平，足以产生临床定义的疾病。我们将联合收割机将神经精神疾病患者FCD脑的下一代测序与先进的生物信息学、单细胞测序、完整的临床相关神经解剖学和小鼠建模相结合。我们将：1]在表现为自闭症或癫痫的FCD的回顾性和前瞻性队列中测试新生体细胞突变。2]将遗传疾病负担与临床、影像学、组织病理学和单细胞测序结果相关联。3]哺乳动物大脑皮层中未发现的从头突变改变祖细胞功能的机制。

 DESCRIPTION (provided by applicant): The recent discovery that de novo zygotic mutations in the form of CNVs and point mutations make major contributions to neuropsychiatric diseases such as schizophrenia and autism begs the question as to the degree to which de novo post-zygotic mosaic mutations also contribute to disease. In this model, a mutation that occurs post-zygotically can seed some percentage of cells in the brain, and is sufficient to lead to neuronal dysfunction and disease. The approach of sequencing only non-neural tissues such as blood may underpower the detection of mosaicism, because mutations may be restricted to neural tissue. This proposal brings together a highly productive and collaborative team, in which each member contributes a special resource to make this effort truly unique. Gleeson and Mathern recently identified among the first de novo somatic mutations in the developing brain in the condition known as `hemimegalencephaly' (HME), a catastrophic neuropsychiatric condition associated with focal cortical disorganization (FCD). By comparing DNA from diseased brain vs. blood, we identified de novo somatic mutations in PIK3CA, AKT3 and MTOR, part of the mTOR pathway, in as few as 8% of brain cells, resulting in perturbations in an entire cerebral hemisphere. Courchesne and Roy recently identified focal patches of abnormal laminar cytoarchitecture in frontal and temporal cortex in the majority of available brain samples of children studied with autism (ASD), and we suggest focal patches akin to FCD may have similar mutations and contribute to disease. The goal of this application is to extend the discovery of mosaicism in patients with epilepsy and autism in which neurohistopathological evidence points to FCD, by sequencing dysplasias compared with adjacent normal tissue and/or blood at the DNA and RNA level at the single-cell level. We aim to uncover key sets of genes, in which specific de novo mutations, in specific locations, at specific mosaicism levels, is sufficient to produce clinically defined disease. We will combine next-generation sequencing of FCD brain from patients with neuropsychiatric disease with advanced bioinformatics, single-cell sequencing, complete clinical correlated neuroanatomy and mouse modeling. We will: 1] Test for de novo somatic mutations in a retrospective and prospective cohort of FCD presenting with autism or epilepsy. 2] Correlate genetic disease burden with clinical, imaging, histopathological and single-cell sequencing findings. 3] Test mechanisms by which uncovered de novo mutations alter progenitor cell functions in mammalian cerebral cortex.