Somatic Mutation in Intractable Focal Epilepsy

难治性局灶性癫痫的体细胞突变

• 批准号: 10063291
• 负责人: Peter B Crino
• 金额: $ 73.34万
• 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/10063291
• 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; Diagnostic radiologic examination; Disease; Electroencephalography; Electrophysiology (science); Epilepsy; Evaluation; Excision; Exhibits; FRAP1 gene; Focal Seizure; Frequencies; Functional disorder; Gene Frequency; Genes; Genetic; 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; deep sequencing; exome sequencing; gene discovery; genetic variant; improved; malformation; novel; prospective; 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.

项目概要 患有难治性局灶性癫痫且结构成像正常（非病变局灶性癫痫，NLFE）的个体 治疗挑战。当未检测到病变时，很难定位癫痫病灶，需要进行手术 成功难以捉摸。目前尚不清楚放射学结构正常的皮层如何发生局灶性癫痫发作，并且 低于标准 3T MRI 分辨率的病理学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 的体细胞突变是部分 NLFE 的原因。一些 影像学正常病例表现出 FCD1a，表明体细胞 SLC35A2 突变可以解释 用于结构正常和异常皮质中的癫痫发作，并将 SLC35A2 确定为第一个潜在基因 FCD1a 和 NLFE。我们最近在成像正常的病例中发现 PLXNB1 和 BRAF 的体细胞脑变异 但FCD2a在病理学上。 PLXNB1可能代表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影像学 NLFE，其中一些具有异常病理学。作为基因鉴定 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。 我们将进一步探索射线照相NLFE的体细胞遗传学，包括1）基因发现的复制 在新病例中，需要进行额外的基因鉴定，并对低频致病等位基因进行更深入的测序； 2） 澄清与特定体细胞突变相关的表型，3）开发成像技术来检测细微的突变 异常； 4) 变异等位基因频率 (VAF) 与特定活检部位的病理学和脑电图的相关性 在切除的大脑内，5）当突变不存在时，区域病理学与脑电图的关联。 在目标 1 中，我们将定义 NLFE 的体细胞遗传景观。在外科癫痫样本中，我们将进行 对 NLFE 患者癫痫病灶切除的大脑进行超深度全外显子组测序 鉴定 SLC35A2、PLXNB1、BRAF 和其他基因中的其他体细胞突变。在目标 2 中，我们将定义 NLFE 中的基因型-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 个体的特定基因中，重点关注癫痫发作时的年龄、 术前先进的 3T 和 7T MRI 以及计算后处理和组织病理学分析 切除的组织。在目标 3 中，我们将定义致病性的区域脑电图、病理和等位基因负担 NLFE 内的体细胞变异。在癫痫手术期间，我们将从用于治疗的组织中进行 4-6 次活检 使用 MRI 定位、电生理学引导的手术进行切除。我们将表征病理学和脑电图 每次活检中的放电模式，区分脑电图指定的癫痫焦点（核心）与周围（半影）。 我们将对每次活检中被认为致病的变异进行定量基因分型，以建立每次活检的 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联。这将定义 VAF、EEG 放电模式和病理学之间的关联。