Functional variants in HCN4 and CACNA1H may contribute to genetic generalized epilepsy.
Functional variants in HCN4 and CACNA1H may contribute to genetic generalized epilepsy.
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DOI：
10.1002/epi4.12068
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发表时间：
2017-09-01
期刊：
影响因子：
3
通讯作者：
Maljevic, Snezana
中科院分区：
文献类型：
--
作者：
Becker, Felicitas;Reid, Christopher A;Maljevic, Snezana
目的：遗传性全身性癫痫（GGE）包括以起源于丘脑-皮层回路内的棘波放电（SWD）为特征的癫痫发作障碍。超极化激活（HCN）和T型钙离子通道是这些脑区节律活动的关键调节剂。在这里，我们筛选HCN 4和CACNA 1H基因的潜在贡献的变体，并提供其功能analysis.Methods：有针对性的基因测序进行了20个无关的家族性病例与不同亚型的GGE，并在230个种族匹配的对照结果证实。在tsA 201细胞和非洲爪蟾卵母细胞中分别对CACNA 1H和HCN 4中的选定变体进行了功能评估，结果：我们在一个家族的两个受影响的成员中发现了一种新的CACNA 1H（p.G1158S）变体。其中一人还携带HCN 4（p.P1117L）变异体，该变异体遗传自未受影响的母亲。在一个单独的家庭中，在几个受影响的成员之一中发现了HCN 4变体（p.E153G）。CACNA 1H（p.G1158S）的电压钳分析显示了一个小但显著的功能增益，包括电流密度增加和稳态失活的去极化偏移。HCN 4 p.P1117L和p.G153E都引起了超极化转变的激活和降低电流振幅，导致了loss-of-function.Significance：我们的结果是一致的模型，表明累积贡献的微妙的功能变化的离子通道癫痫发作的易感性和GGE。
Objective: Genetic generalized epilepsy (GGE) encompasses seizure disorders characterized by spike-and-wave discharges (SWD) originating within thalamo-cortical circuits. Hyperpolarization-activated (HCN) and T-type Ca2+ channels are key modulators of rhythmic activity in these brain regions. Here, we screened HCN4 and CACNA1H genes for potentially contributory variants and provide their functional analysis.Methods: Targeted gene sequencing was performed in 20 unrelated familial cases with different subtypes of GGE, and the results confirmed in 230 ethnically matching controls. Selected variants in CACNA1H and HCN4 were functionally assessed in tsA201 cells and Xenopus laevis oocytes, respectively.Results: We discovered a novel CACNA1H (p.G1158S) variant in two affected members of a single family. One of them also carried an HCN4 (p.P1117L) variant inherited from the unaffected mother. In a separate family, an HCN4 variant (p.E153G) was identified in one of several affected members. Voltage-clamp analysis of CACNA1H (p.G1158S) revealed a small but significant gain-of-function, including increased current density and a depolarizing shift of steady-state inactivation. HCN4 p.P1117L and p.G153E both caused a hyperpolarizing shift in activation and reduced current amplitudes, resulting in a loss-of-function.Significance: Our results are consistent with a model suggesting cumulative contributions of subtle functional variations in ion channels to seizure susceptibility and GGE.