离子通道基因突变致早发癫痫性脑病17例临床特征和基因突变分析

Clinical features and ion channel gene mutations analysis in 17 cases of early-onset epileptic encephalopathy

目的分析离子通道基因突变致早发癫痫性脑病的临床特征和基因突变,明确病因,指导治疗,并为遗传咨询提供依据。方法收集2014年6月至2018年5月天津市儿童医院神经内科收治的17例离子通道基因突变致早发癫痫性脑病患儿临床资料和患儿及其父母外周血样本,应用疾病基因靶向二代测序技术进行癫痫基因测序分析,发现致病性离子通道基因突变,被证实的突变均用Sanger测序验证,并明确突变的来源。结果17例早发癫痫性脑病患儿中,3例为遗传性基因突变,14例为新生基因突变。其中Dravet综合征8例(47.1%),5例为SCN1A基因错义突变,3例为SCN1A基因无义突变;大田原综合征1例(5.9%)为KCNQ2基因错义突变;非特异性癫痫性脑病8例(47.1%),发现可疑致病性突变中SCN2A基因错义突变、SCN4A基因错义突变、SCN8A基因错义突变、KCNQ2基因错义突变、KCNH5基因错义突变、CACNA1A基因错义突变、GRIN2A基因错义突变、GRIN3A基因错义突变各1例。17例均予2种及2种以上抗癫痫药物治疗,4例予生酮饮食,1例补充维生素B6辅助抗癫痫治疗。随访11~96个月,3例(17.6%)癫痫发作完全控制,7例(41.2%)癫痫发作减少≥50%,7例(41.2%)癫痫发作减少<50%。结论早发癫痫性脑病临床表型多样,离子通道基因突变是最常见的遗传性病因。本研究发现3例SCN1A基因错义突变、2例SCN1A基因无义突变、1例SCN2A基因错义突变、1例CACNA1A基因错义突变,1例KCNH5基因错义突变为未见报道新发位点突变,丰富了早发癫痫性脑病的相关离子通道基因型。

Objective To analyze the clinical characteristics and gene mutations of early-onset epileptic encephalopathy(EOEE) caused by ion channel gene mutation, to identify the etiology, to guide the treatment and to provide the basis for genetic counseling. Methods The clinical data from 17 children with EOEE caused by ion channel gene mutation and the peripheral blood of the children and their parents were collected from June 2014 to May 2018 at the Department of Neurology, Tianjin Children′s Hospital.Epilepsy gene sequencing was performed by using disease gene targeting second generation sequencing technology.The mutation of pathogenic ion channel gene was found.The confirmed mutations were verified by Sanger sequencing and the source of the mutation was identified. Results Among 17 case with EOEE, 3 cases had genetic mutation, and 14 cases had denovo mutations.Dravet syndrome was found in 8 cases (47.1%), there were SCN1A gene missense mutation in 5 cases, SCN1A gene nonsense mutation in 3 cases, KCNQ2 gene missense mutation in 1 case (5.9%) and non-specific epileptic encephalopathy in 8 cases (47.1%). SCN2A gene missense mutation, SCN4A gene missense mutation, SCN8A gene missense mutation, KCNQ2 gene missense mutation and KCNH gene missense mutation were found in suspected pathogenic mutations.There were 1 missense mutation out of 5 genes, 1 missense mutation of CACNA1A gene, 1 missense mutation of GRIN2A gene and 1 missense mutation of GRIN3A gene.Seventeen patients were treated with 2 or more antiepileptic drugs, 4 with ketogenic diet and 1 with vitamin B6 supplementation.During 11 to 96 months of follow-up, seizures were completely controlled in 3 cases (17.6%), decreased in 7 cases (41.2%) by more than 50%, and decreased in 7 cases (41.2%) by less than 50%. Conclusions The clinical phenotypes for children with unexplained EOEE are varied, and gene mutations of ion cha-nnel are most common.Some gene sites are denovo mutations which have not been reported such as missense mutation for 3 case SCN1A gene, 1 case SCN2A gene, 1 case CACNA1A gene, 1 case KCNH5 gene, and nonsense mutation for 2 case SCN1A gene, which have enriched the mutation spectrum of EOEE.