Somatic Mutation in Intractable Focal Epilepsy

难治性局灶性癫痫的体细胞突变

• 批准号: 10662245
• 负责人: Peter B Crino
• 金额: $ 61.65万
• 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/10662245
• 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.

项目总结 顽固性局灶性癫痫且结构成像正常(非狼疮性局灶性癫痫，NLFE)的个体 治疗挑战。当没有发现病变时，癫痫灶的定位是困难的，而且是外科手术。 成功难以捉摸。目前尚不清楚放射学结构正常的大脑皮质是如何发生局灶性癫痫的，以及 病理是否低于标准3T MRI的分辨率是常见的元凶。我们最近证明了 SLC35A2编码UDP半乳糖转运体，它的体细胞突变导致了一些NLFE。一些人 放射学正常病例显示FCD1a，表明体细胞SLC35A2突变可以解释 在结构正常和异常的皮质中起病，并确定SLC35A2是第一个潜在的基因 FCD1a和NLFE。我们最近在成像正常的病例中发现了PLXNB1和BRAF的体细胞脑变异 而病理上的FCD2a。PLXNB1可能是FCD2中第一个非mTOR基因。我们由此证明了 脑体细胞变异可导致放射学上的NLFE，其中一些具有异常的病理。AS基因鉴定 阐明局灶性癫痫的生物学并为治疗提供信息，这些发现可能具有重大的临床意义。 我们将进一步探索放射学NLFE的体细胞遗传学，包括1)基因发现的复制 在新病例中，进行额外的基因鉴定，并对较低频率的致病等位基因进行更深入的测序；2) 阐明与特定体细胞突变相关的表型，3)发展成像以检测细微的 异常；4)变异等位基因频率(VAF)与病理和特定活检部位脑电的相关性 5)当没有突变时，局部病理与脑电的关系。 在目标1中，我们将定义NLFE的体细胞遗传图谱。在外科癫痫样本中，我们将进行 NLFE患者癫痫灶脑组织的超高深度全外显子组测序 鉴定SLC35A2、PLXNB1、BRAF和其他基因的其他体细胞突变。在目标2中，我们将定义 NLFE的基因型-表型相关性。我们将确定与体细胞突变相关的表型 在一组NLFE患者的特定基因中，专注于癫痫发作的年龄，异常 术前先进的3T和7T MRI及其计算机后处理，并对其进行组织病理学分析 切除的组织。在目标3中，我们将定义致病的局部脑电、病理和等位基因负担 NLFE内的体细胞变异。在癫痫手术期间，我们将从组织中进行4-6次活组织检查 使用MRI定位、电生理引导的手术切除。我们将描述病理学和EEG的特征 每次活检的放电模式，区分脑电指定的癫痫灶(核心)和周围(半影区)。 我们将对每个活检组织进行定量分型，以确定被认为致病的变异，以建立每个活检组织的VAF和 当没有突变时，将脑电模式与组织病理异常联系起来。这将定义 房颤、脑电放电模式和病理之间的关系。