Somatic Mosaicism in the Brain of Tourette Syndrome

项目摘要 图雷特综合征（TS）是一种端脑发育障碍， 通过对血液样本的检查，尚未发现致病的遗传变异。在这 我们的建议是，研究体细胞突变是否可能部分地导致 ts.现有的证据表明，细胞在形成后积累体细胞突变。 受精卵，这意味着人体细胞没有相同的DNA序列。除了 单核苷酸变异（SNV）和小插入/缺失（InDel），细胞可以积累 拷贝数变异（CNV，即，重复和缺失），插入转座 元素、倒位和易位，所有这些都涉及几百到几百万个元素。 个核苷酸脑细胞中出现的体细胞嵌合现象可以解释为什么没有发现 在神经精神疾病如TS中存在一致的、可复制的遗传风险因素， 至少部分是血液基因型和总体表型之间经常观察到的变异性。 无论是在正常发育还是在疾病中，都没有体细胞嵌合现象的估计。测试 假设体细胞突变可能是TS出现的基础，在这个建议中，我们 将发现并量化TS和正常对照大脑中的体细胞基因组变异， 探索这种变化的潜在功能后果。在目标1中，我们将 使用先进的测序技术，全面发现谱系特异性和 区域特异性体细胞基因组变异：SNV，InDel，CNV，反转录转座子插入， 倒位和易位。分析将涉及20个TS脑和匹配的20个正常脑 控制大脑马赛克变体将在前额叶皮层（PFC）中被发现和验证， 运动前皮质（PMC）和纹状体（STR），这三个区域与TS密切相关， 从这些区域分离的特定细胞谱系，包括锥体神经元、中型棘状神经元、 神经元、中间神经元和小胶质细胞。在目标2中，我们将选择10个基因组变体， 使用CRISPR技术将其工程化为iPSC和转基因小鼠，并表征 它们对分子、组织和行为水平的影响。这些具体目标将共同 提供脑中体细胞基因组变异（数量、类型、频率）的第一个估计值， TS和将产生关于它们对大脑发育的重要性的假设。

Project Summary Tourette Syndrome (TS) is a disorder of the developing telencephalon for which no significant causative genetic variant has yet emerged through the examination of blood samples. In this proposal we investigate whether somatic mutations might underlie in part the pathogenesis of TS. Existing evidence suggests that cells accumulate somatic mutations after the formation of the zygote, implying that cells of the human body do not have identical DNA sequence. Besides single nucleotide variation (SNV) and small insertion/deletions (InDels), cells can accumulate copy number variations (CNVs, i.e., duplications and deletions), insertions of transposable elements, inversions and translocations, all involving from few hundreds to several millions of nucleotides. Somatic mosaicism arising in brain cells could explain the failure to discover consistent, replicable genetic risk factors in neuropsychiatric disorders like TS, and underlie at least in part the frequently observed variability between blood genotype and overall phenotype. There is no estimate of somatic mosaicism in either normal development or in disease. To test the hypothesis that somatic mutations might underlie the emergence of TS, in this proposal we will discover and quantify somatic genome variation in TS and normal control brains, followed by exploration of potential functional consequences of this variation. In Aim 1, we will perform using advanced sequencing techniques comprehensive discovery of lineage-specific and region-specific somatic genomic variations: SNVs, InDels, CNVs, retrotransposon insertions, inversion and translocations. The analysis will involve 20 TS brains and matched 20 normal control brains. Mosaic variants will be discovered and validated in prefrontal cortex (PFC), premotor cortex (PMC) and striatum (STR), three regions strongly implicated in TS, as well as in specific cell lineages isolated from these regions, including pyramidal neurons, medium spiny neurons, interneurons and microglial cells. In Aim 2, we will select 10 genomic variants, engineer them into iPSCs and in transgenic mice using CRISPR technologies, and characterize their impact on the molecular, tissue and behavior level. Together, these specific aims will provide the first estimate of somatic genomic variation (number, type, frequency) in the brain of TS and will yield hypotheses about their significance for brain development.