Somatic Mutation in Intractable Focal Epilepsy

难治性局灶性癫痫的体细胞突变

• 批准号: 10888458
• 负责人: Peter B Crino
• 金额: $ 8.22万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-15 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10888458
• 关键词: Age; Alleles; Area; BRAF gene; Biological Markers; Biology; Biopsy; Biopsy Specimen; Brain; Brain imaging; Brain region; Caring; Cerebral cortex; Characteristics; Childhood; Clinical; Cortical Dysplasia; DNA Sequence Alteration; DNA sequencing; Detection; Development; Electroencephalography; Electrophysiology (science); Epilepsy; Evaluation; Excision; Exhibits; FRAP1 gene; Focal Seizure; Frequencies; Functional disorder; Gene Frequency; Genes; Genetic; Genetic Predisposition to Disease; Genotype; Histopathology; Image; Individual; Investigation; Lesion; Link; Magnetic Resonance Imaging; Medical; Mutation; Operative Surgical Procedures; Outcome; Partial Epilepsies; Pathogenicity; Pathologic; Pathology; Pattern; Phenotype; Positioning Attribute; Procedures; Recurrence; Resected; Resolution; Role; Sample Size; Sampling; Seizures; Signal Transduction; Site; Somatic Mutation; Source; Structure; Techniques; Time; Tissues; UDP-galactose transporter; Variant; brain tissue; clinical phenotype; cohort; exome sequencing; gene discovery; genetic variant; improved; malformation; novel; prospective; radiological imaging; structural imaging; success; surgery outcome

PROJECT SUMMARY Individuals with intractable focal epilepsy and normal structural imaging (non-lesional focal epilepsy, NLFE) pose treatment challenges. When no lesion is detected, localization of the seizure focus is difficult and surgical success elusive. It is unknown how focal seizures arise in cortex with radiographically normal structure, and whether pathology below the resolution of standard 3T MRI is a common culprit. We recently demonstrated that somatic mutations in SLC35A2, which encodes a UDP galactose transporter, account for some NLFE. Some radiographically normal cases exhibited FCD1a, demonstrating that somatic SLC35A2 mutations can account for seizure onset in structurally normal and abnormal cortex, and identifying SLC35A2 as the first gene underlying FCD1a and NLFE. We recently found somatic brain variants in PLXNB1 and BRAF in cases with normal imaging but FCD2a on pathology. PLXNB1 may represent the first non-mTOR gene in FCD2. We thereby demonstrated brain somatic variants can result in radiographic NLFE, some with abnormal pathology. As gene identification illuminates the biology of focal epilepsy and informs therapy, discoveries can have major clinical implications. We will further explore the somatic genetics of radiographic NLFE, including 1) replication of gene discoveries in new cases, additional gene identification, and deeper sequencing for lower-frequency pathogenic alleles; 2) clarifying phenotypes associated with specific somatic mutations, 3) development of imaging to detect subtle abnormalities; 4) correlation of variant allele frequency (VAF) with pathology and EEG from specific biopsy sites within resected brain and 5) association of regional pathology with EEG when mutations are absent. In Aim 1 We will define the somatic genetic landscape of NLFE. In surgical epilepsy samples, we will conduct ultra-high-depth whole exome sequencing of brain resected from the seizure focus from individuals with NLFE to identify additional somatic mutations in SLC35A2, PLXNB1, BRAF, and other genes. In Aim 2 we will define genotype-phenotype correlations in NLFE. We will determine phenotypes associated with somatic mutations in specific genes in a cohort of individuals with NLFE, focusing on age at onset of epilepsy, abnormalities on presurgical advanced 3T and 7T MRI with computational post-processing, and histopathologic analysis of resected tissue. In Aim 3 we will define the regional EEG, pathological, and allelic burden of pathogenic somatic variants within NLFE. During epilepsy surgery, we will perform 4-6 biopsies from tissue destined for resection using an MRI-localized, electrophysiology-guided procedure. We will characterize pathology and EEG firing pattern in each biopsy, distinguishing the EEG-designated seizure focus (core) vs. surround (penumbra). We will quantitatively genotype each biopsy for variants deemed pathogenic to establish per-biopsy VAF and when mutations are absent, correlate EEG pattern with histopathologic abnormalities. This will define associations among VAF, EEG firing pattern, and pathology.

项目摘要 具有顽固性局灶性癫痫和正常结构成像（非局灶性癫痫，NLFE）姿势的个体 治疗挑战。当未检测到病变时，癫痫发作的定位很困难和外科手术 成功难以捉摸。尚不清楚具有射线照相正常结构的皮层中的局灶性癫痫发作，并且 低于标准3T MRI分辨率的病理是否是常见的罪魁祸首。我们最近证明了 编码UDP半乳糖转运蛋白的SLC35A2中的体细胞突变占NLFE。一些 射线照相正常病例表现出FCD1A，表明体细胞SLC35A2突变可以考虑 对于结构正常和异常皮质的癫痫发作，并将SLC35A2鉴定为第一个基因 FCD1A和NLFE。我们最近在正常成像的情况下发现PLXNB1和BRAF中的体细胞变异 但是关于病理学的FCD2A。 PLXNB1可能代表FCD2中的第一个非MTOR基因。因此，我们证明了 脑体细胞变异可能会导致X线摄影NLFE，有些具有异常病理。作为基因鉴定 阐明了局灶性癫痫的生物学并告知治疗，发现可能具有重大的临床意义。 我们将进一步探索射线照相NLFE的躯体遗传学，包括1）复制基因发现 在新情况下，额外的基因鉴定和更深层次的测序，用于低频致病等位基因； 2） 澄清与特定体细胞突变相关的表型，3）成像的发展以检测微妙的 异常； 4）变异等位基因频率（VAF）与特定活检部位的病理和脑电图的相关性 在切除的大脑和5）缺乏突变时区域病理与脑电图的关联。 在AIM 1中，我们将定义NLFE的体细胞遗传景观。在手术癫痫样品中，我们将进行 从NLFE的个体癫痫发作的焦点切除的大脑的超高深度整个外显子组测序 确定SLC35A2，PLXNB1，BRAF和其他基因中的其他体细胞突变。在AIM 2中，我们将定义 NLFE中的基因型 - 表型相关性。我们将确定与躯体突变相关的表型 在具有NLFE的个体中的特定基因中，重点是癫痫发作时的年龄，异常 具有计算后处理的预性高级3T和7T MRI，以及组织病理学分析 切除的组织。在AIM 3中，我们将定义致病性的脑电图，病理和等位基因负担 NLFE内的体细胞变体。在癫痫手术期间，我们将从注定的组织中进行4-6次活检 使用MRI定位的电生理学指导程序切除。我们将表征病理学和脑电图 每个活检中的射击模式，区分脑电图指定的癫痫发作焦点（核心）与环绕（Penumbra）。 我们将定量基因型的每种活检，以供被认为是病原的变体，以建立人均VAF和 当突变不存在时，将脑电图模式与组织病理学异常相关。这将定义 VAF，脑电图射击模式和病理学之间的关联。