[Clinical and genetic spectrum of SCN2A gene associated epilepsy and episodic ataxia].

Objective: To explore the clinical manifestations and genetic characteristics of patients with epilepsy and episodic ataxia caused by SCN2A gene variation. Methods: The clinical data of seizure manifestation, imaging examination and genetic results of 5 patients with epilepsy and (or) episodic ataxia because of SCN2A gene variation admitted to the Department of Pediatrics, the Third Affiliated Hospital of Zhengzhou University from July 2017 to January 2021 were analyzed retrospectively. Results: Among 5 patients, 4 were female and 1 was male. The onset age of epilepsy ranged from 4 days to 8 months. There were 2 cases of benign neonatal or infantile epilepsy and 3 cases of epileptic encephalopathy, in whom 1 case had development retardation,1 case transformed from West syndrome to infantile spasm and another one transformed from infantile spasm to Lennox-Gastaut syndrome. One case of benign neonatal-infantile epilepsy was characterized by neonatal onset seizures and episodic ataxia developed at the age of 78 months. Electroencephalograms at first visit of 5 cases showed that 2 cases were normal, 1 case had focal epileptic discharge, and 2 cases had multi-focal abnormal discharge with peak arrhythmia. The brain magnetic resonance imaging (MRI) of 3 cases were nomal, 1 case was abnormal (brain atrophy with decreased white matter) and the results of 1 case was unknown. The follow-up time ranged from 17 months to 89 months. Four cases of epilepsy were controlled and 1 case died at 2 years of age. Two cases had normal intelligence and motor development, 2 had moderate to severe intelligence retardation and motor critical state, and 1 had moderate to severe intelligence and motor development retardation. SCN2A gene variations were identified in all cases. There were 4 missense variations and 1 frameshift variation. Three variations had not been reported so far, including c.4906A>G,c.3643G>T,c.638delT. Conclusions: Variations in SCN2A gene can cause benign neonatal or infantile epilepsy and epileptic encephalopathy. Some children develop episodic ataxia with growing age. The variation of SCN2A gene is mainly missense variation.目的： 探讨SCN2A基因变异所致癫痫及共济失调的临床及遗传学特点。 方法： 回顾性总结郑州大学第三附属医院2017年7月至2021年1月收治的5例SCN2A基因变异所致癫痫伴或不伴发作性共济失调患儿的发作表现、影像学检查及基因检测结果等临床资料，分析其临床及遗传学特点。 结果： 5例患儿中女4例、男1例，癫痫起病年龄4日龄至8月龄，癫痫发作类型有新生儿或婴儿良性癫痫2例，癫痫性脑病3例（1例存在发育落后，1例为大田原综合征之后转化为婴儿痉挛症，1例为婴儿痉挛症之后转化为Lennox-Gastaut 综合征）；其中新生儿良性癫痫中有1例早期为新生儿惊厥，6岁6月龄时出现发作性共济失调。初诊时发作间期脑电图2例正常，1例局灶性癫痫样放电，2例大量多灶异常放电且有高度失律。头颅磁共振成像3例正常，1例表现为脑萎缩伴脑白质减少，1例结果不详。随访1年5个月至7年5个月，4例患儿癫痫均控制稳定，1例2岁时死亡。2例患儿智力及运动发育正常，2例智力中、重度落后、运动临界状态，1例智力及运动均为中、重度落后。5例患儿均有SCN2A基因变异，其中错义变异4例和移码变异1例，3例患儿变异位点未见报道，分别为c.4906A>G、c.3643G>T、c.638delT。 结论： SCN2A基因变异可致新生儿或婴儿良性癫痫、癫痫性脑病等临床特点。部分患儿随着年龄的增长可出现发作性共济失调。SCN2A基因变异以错义变异为主。.