Abstract

KCTD7 is a member of the potassium channel tetramerization domain-containing protein family and has been associated with progressive myoclonic epilepsy (PME), characterized by myoclonus, epilepsy, and neurological deterioration. Here we report four affected individuals from two unrelated families in which we identified KCTD7 compound heterozygous single nucleotide variants through exome sequencing. RNAseq was used to detect a non-annotated splicing junction created by a synonymous variant in the second family. Whole-cell patch-clamp analysis of neuroblastoma cells overexpressing the patients’ variant alleles demonstrated aberrant potassium regulation. While all four patients experienced many of the common clinical features of PME, they also showed variable phenotypes not previously reported, including dysautonomia, brain pathology findings including a significantly reduced thalamus, and the lack of myoclonic seizures. To gain further insight into the pathogenesis of the disorder, zinc finger nucleases were used to generate kctd7 knockout zebrafish. Kctd7 homozygous mutants showed global dysregulation of gene expression and increased transcription of c-fos, which has previously been correlated with seizure activity in animal models. Together these findings expand the known phenotypic spectrum of KCTD7-associated PME, report a new animal model for future studies, and contribute valuable insights into the disease.

摘要

KCTD7 是含钾通道四聚化结构域蛋白家族的成员，与进行性肌阵挛性癫痫 (PME) 相关，其特征是肌阵挛、癫痫和神经功能恶化。在这里，我们报告了来自两个无关家庭的四个受影响的个体，我们在其中发现了 KCTD7通过外显子组测序复合杂合单核苷酸变体。RNAseq 用于检测由第二个家族中的同义变体创建的未注释剪接点。过度表达患者变异等位基因的神经母细胞瘤细胞的全细胞膜片钳分析显示钾调节异常。虽然所有四名患者都经历了 PME 的许多常见临床特征，但他们还表现出以前没有报道过的可变表型，包括自主神经功能障碍、包括显着减少的丘脑在内的脑病理学发现以及缺乏肌阵挛性癫痫发作。为了进一步了解这种疾病的发病机制，锌指核酸酶被用来产生kctd7敲除斑马鱼。Kctd7纯合突变体显示出基因表达的整体失调和c-fos转录增加，这在动物模型中与癫痫发作活动相关。这些发现共同扩展了KCTD7相关 PME 的已知表型谱，为未来研究报告了一种新的动物模型，并为该疾病提供了有价值的见解。