KCNQ2/3 channels in neonatal-onset epilepsy and encephalopathy

描述（由申请人提供）：KCNQ 2或KCNQ 3突变引起良性家族性新生儿癫痫发作（BFNS），这是一种显性遗传的高度外显早发性癫痫综合征。BFNS在新生儿期引起频繁的癫痫发作，但癫痫发作缓解后，受影响的个体正常发育。然而，令人信服的证据表明，KCNQ 2突变的一个子集在持续性和致残性CNS和神经肌肉疾病。KCNQ 2家系表现出疼痛性肌震颤（无癫痫发作）、新生儿癫痫发作后肌震颤、新生儿期后癫痫和癫痫伴严重智力残疾。最重要的是，最近的一项欧洲-澳大利亚合作研究描述了10%（8/80）的严重、散发性、早发性癫痫性脑病（EEG）病例中的新发KCNQ 2突变。如本更新申请中所披露的，我们的实验室已经确定了另外6名来自北美的携带新型KCNQ 2突变的个体。虽然遗传背景和表观遗传学等因素可能会影响这些表型，但我们的分析表明，在AML患者中从头KCNQ 2突变可能作为有效的显性阴性，抑制活性高达94%（16倍），而已知的BFNS突变通常会降低活性20-50%（2倍或更少）。 在这里，我们建议定义的发育时间过程中，在正常啮齿动物，KCNQ 2突变小鼠，和人体组织中检测的海马结构和体感和运动新皮层的神经元轴突膜的KCNQ 2和KCNQ 3通道的到来。在解剖学研究的同时，我们还将通过体外分析、膜片钳记录和转基因动物模型，在亚细胞、细胞和行为水平上分析海马和新皮质轴突KCNQ通道的功能。最后，我们将分析和比较两种KCNQ开放剂药物的效力，最大效力和亚基特异性不同，在体外激活通道和终止癫痫发作在体内。

DESCRIPTION (provided by applicant): Mutations in KCNQ2 or KCNQ3 cause benign familial neonatal seizures (BFNS), a dominantly-inherited, highly penetrant early-onset epilepsy syndrome. BFNS causes frequent seizures during the neonatal period, but after seizures remit, affected individuals develop normally. However, compelling evidence now implicates a subset of KCNQ2 mutations in persistent and disabling CNS and neuromuscular diseases. KCNQ2 pedigrees exhibit painful myokymia (without seizures), myokymia after neonatal seizures, epilepsy after the neonatal period, and epilepsy with significant intellectual disability. Most importantly, a recent Euro-Australian collaborative study describes de novo KCNQ2 mutations in 10% of cases (8/80) of severe, sporadic, early- onset epileptic encephalopathy (EEE). As disclosed in this renewal application, our lab has ascertained 6 additional individuals from North America with EEE bearing novel KCNQ2 mutations. Although factors such as genetic background and epigenetics may influence these phenotypes, our analysis suggests mechanisms whereby the de novo KCNQ2 mutations in EEE patients may act as potent dominant-negatives, suppressing activity up to 94% (16-fold), whereas known BFNS mutations are known to generally reduce activity by 20-50% (2-fold or less). Here, we propose to define the developmental time course for the arrival of KCNQ2 and KCNQ3-containing channels at the axonal membrane of neurons in the hippocampal formation and the somatosensory and motor neocortex, assayed in normal rodents, KCNQ2 mutant mice, and human tissue. In parallel with anatomical study, we will also analyze the function of hippocampal and neocortical axonal KCNQ channels at the subcellular, cellular, and behavioral level through in vitro analysis, patch clamp recording, and transgenic animal models. Finally, we will analyze and compare the efficacy two KCNQ opener drugs which differ in potency, maximal efficacy and subunit specificity, to activate channels in vitro and terminate seizures in vivo.