Temporal Lobe Epilepsy and Retrotransposons

 描述(由申请人提供)：特发性(隐源性)癫痫是一种常见的慢性脑部疾病，影响美国人口的1%-2%，由于相关的发病率和死亡率，造成了重大的公共卫生问题。这种复杂的脑部疾病的一个亚型--颞叶癫痫(TLE)--尤其繁重，因为相当一部分患者对抗惊厥药物没有反应。如果通过成像和/或EEG可以定位癫痫灶，TLE患者通常选择部分切除受影响的颞叶，因为他们每天都有癫痫发作，尽管有多种药物治疗方案。尽管遗传风险被认为在TLE中起作用，但识别常见的风险等位基因的成功有限。在过去的5年中，越来越多的数据表明，神经元胚胎的发生伴随着LINE1(L1)反转录转座子(RTPs)的异常激活，以至于发育中的神经元可能积累新的L1s插入。这导致了中枢神经系统神经元群体中的大量嵌合体。虽然大多数这些体细胞新生L1对神经元功能几乎没有影响(可能是因为它们出现在基因沙漠或大内含子中，或者出现在该细胞功能不需要的基因中)，但有些可能会干扰正常的神经元活动，因为它们插入了特定神经元正常功能所需的基因。如果一个或多个功能性从头L1出现在中枢神经系统发育的早期，来自该神经元前体的所有子代神经元也将携带L1插入，可能导致注定成为癫痫灶的神经元功能障碍。这项建议将利用来自顽固性TLE患者的中枢神经系统组织(在开颅手术中获得)，这些患者已经接受了一侧颞叶的治疗性部分切除。使用荧光辅助的颞叶神经元核细胞分选，然后高通量测序和与参考基因组的比对，将完成从头L1的检测。用Droplet数字聚合酶链式反应(Droplet Digital PCR)检测新基因L1的神经元DNA等位基因频率。通过这种方式，有望发现与特发性TLE有关的从头基因L1。

 DESCRIPTION (provided by applicant): Idiopathic (cryptogenic) epilepsy is a common, chronic group of brain disorders, affecting 1-2% of the US population, creating a significant public health problem because of the associated morbidity and mortality. One subtype of this complex group of brain disorders, temporal lobe epilepsy (TLE), is particularly burdensome, because a substantial fraction of patients do not respond to anticonvulsant medications. If the seizure focus can be localized by imaging and/or EEG, the TLE patient often elects to have a partial resection of the affected temporal lobe, because they have daily seizures, despite multiple pharmacotherapy regimens. Although genetic risk is thought to play a role in TLE, identification of common risk alleles has had limited success. In the past 5 years, data have accumulated to prove that neuronal embryogenesis is accompanied by activation of LINE1 (L1) retrotransposons (RTPs) to an unexpected degree, such that developing neurons may accumulate de novo L1s insertions. This results in a substantial mosaicism within populations of CNS neurons. While most of these somatic de novo L1s will have little effect on neuronal function (perhaps because they occur in gene deserts or in large introns or in genes not required for that cell's function), some may interfere with normal neuronal activity because they have inserted into a gene needed by that particular neuron for normal function. If one or more functional de novo L1s occur early in CNS development, all the daughter neurons that derive from that neuronal precursor will also carry the L1 insertion, perhaps leading to a dysfunctional population of neurons destined to become an epileptic focus. This proposal will leverage CNS tissue (obtained at craniotomy) from patients with intractable TLE, who have undergone a therapeutic partial resection of one temporal lobe. Using fluorescence-assisted cell sorting of temporal lobe neuronal nuclei, followed by high-throughput sequencing and alignment to the reference genome, detection of de novo L1s will be done. The allele frequencies in neuronal DNA of selected de novo intragenic L1s will be determined by droplet digital PCR. In this manner, it is expected that de novo intragenic L1s, contributing to idiopathic TLE, will be discovered.