Combined Approach to Genetic Modifiers of Inherited Epilepsy

描述(申请人提供)：电压门控钠通道突变与几种类型的人类癫痫有关，包括遗传性(全身性)癫痫伴发热性癫痫(GEFS+)和Drave氏综合征。在这些遗传性癫痫中，有不同的外显率和临床表型的表达，这表明了遗传修饰物的作用。我们已经建立了具有不同潜在机制的电压门控钠通道和癫痫相关表型突变的小鼠模型。Scn2aQ54转基因小鼠有一种功能获得突变，可导致自发性成人起病的部分运动性癫痫，并具有GEFS+的模型特征。杂合子Scn1a+/-空小鼠是Drave氏综合征的模型，Drave氏综合征是一种严重的婴儿癫痫，伴有进行性恶化并伴有精神运动退化。这些小鼠模型的一个共同特征是癫痫的严重程度取决于遗传菌株背景，这表明遗传修饰物影响表型。与易感(C57BL/6J x SJL/J)F1背景相比，C57BL/6J抗性背景上的Scn2aQ54小鼠发病延迟，严重程度降低，存活率提高。相反，在C57BL/6J背景下，Scn1a+/-小鼠的癫痫表型更为严重，而在129S6/SvEvTac背景下，Scn1a+/-小鼠的癫痫起病时间推迟，存活率提高。基于这些观察，我们假设多种基因修饰物作用于影响原发癫痫突变的外显率和表达能力。在此之前，我们定位了导致Scn2aQ54小鼠品系差异的两个修饰基因座：11号染色体上的Moe1(癫痫修饰基因1)和19号染色体上的Moe2。在之前的资助期间，我们对Moe1区域进行了精细定位和候选基因分析，鉴定了Moe2修饰基因，并确定了影响Scn2aQ54表型的其他修饰基因座。我们建议使用Scn2aQ54和Scn1a+/-小鼠模型继续我们对癫痫调节剂的分析。首先，我们将确定Scn2aQ54修饰基因座上的相关基因。接下来，我们将确定Moe2修饰剂效应的分子基础。最后，我们将在Scn1a+/-小鼠模型中定位遗传修饰基因座，并通过RNA-SEQ进行转录组分析，以加速识别候选基因。我们研究的主要目标是识别和表征影响癫痫易感性和严重程度的修饰基因。这些基因可能与常见的癫痫综合征有更复杂的遗传学联系。癫痫修饰基因的识别将为癫痫发生的基础生物学提供深入的认识，并可能为人类患者的治疗识别新的治疗靶点。 公共卫生相关性：这项建议的主要目标是确定影响遗传性癫痫外显性和严重性的修饰基因。癫痫修饰基因的识别和潜在机制的分析将为癫痫发生的分子事件提供洞察力。这将有助于理解具有更复杂遗传的癫痫的基础，并为改进人类患者的治疗提供新的治疗靶点。

DESCRIPTION (provided by applicant): Mutations in voltage-gated sodium channels have been associated with several types of human epilepsy, including Genetic (Generalized) Epilepsy with Febrile Seizure Plus (GEFS+) and Dravet Syndrome. Within these genetic epilepsies, there is variable penetrance and expressivity of the clinical phenotype, suggesting a role for genetic modifiers. We have developed mouse models with mutations in voltage-gated sodium channels and seizure-related phenotypes with different underlying mechanisms. Scn2aQ54 transgenic mice have a gain-of-function mutation that results in spontaneous, adult-onset partial motor seizures and models features of GEFS+. Heterozygous Scn1a+/- null mice are a model of Dravet Syndrome, a severe, infant-onset epilepsy with progressive worsening accompanied by psychomotor regression. A common feature of these mouse models is that epilepsy severity varies depending on the genetic strain background, suggesting that genetic modifiers influence the phenotype. Scn2aQ54 mice on the resistant C57BL/6J background have delayed onset, decreased severity and improved survival compared to the susceptible (C57BL/6J x SJL/J)F1 background. Conversely, the epilepsy phenotype of Scn1a+/- mice is more severe on the C57BL/6J background, while they have delayed onset and improved survival on the 129S6/SvEvTac strain background. Based on these observations, we hypothesize that multiple genetic modifiers act to influence penetrance and expressivity of the primary epilepsy mutation. Previously we mapped two modifier loci that are responsible for the strain difference in Scn2aQ54 mice: Moe1 (modifier of epilepsy 1) on Chromosome 11 and Moe2 on Chromosome 19. During the previous funding period we performed fine mapping and candidate gene analysis of the Moe1 region, identified the Moe2 modifier gene, and identified additional modifier loci that influence the Scn2aQ54 phenotype. We propose to continue our analysis of epilepsy modifiers using the Scn2aQ54 and Scn1a+/- mouse models. First, we will identify the responsible genes at Scn2aQ54 modifier loci. Next, we will determine the molecular basis of the Moe2 modifier effect. Finally, we will map genetic modifier loci in the Scn1a+/- mouse model and perform transcriptome analysis via RNA-seq for accelerated identification of candidate genes. The major goal of our studies is to identify and characterize modifier genes that influence epilepsy susceptibility and severity. These genes are likely to contribute to common epilepsy syndromes with more complex genetics. Identification of epilepsy modifier genes will provide insight into the basic biology of epileptogenesis and may identify novel therapeutic targets for the treatment of human patients. PUBLIC HEALTH RELEVANCE: The major goal of this proposal is to identify modifier genes that influence penetrance and severity of inherited epilepsy. Identification of epilepsy modifier genes and analysis of the underlying mechanisms will provide insight into the molecular events of epileptogenesis. This will contribute to understanding the basis of epilepsy with more complex inheritance and suggest novel therapeutic targets for the improved treatment of human patients