良性家族性新生儿-婴儿癫痫致病基因谱研究

Spectrum of mutations in benign familial neonatal-infantile epilepsy

目的分析良性家族性新生儿-婴儿癫痫（BFNIE）家系的致病基因谱。方法收集2012年12月至2016年4月在北京大学第一医院儿科就诊的BFNIE家系的临床资料和外周血DNA，首先采用Sanger测序方法筛查PRRT2基因突变，对于未发现PRRT2基因突变的家系再采用靶向捕获二代测序癫痫基因检测包对BFNIE的候选致病基因进行突变筛查。结果共收集7个BFNIE家系，共有30例受累者，其中男15例、女15例，起病年龄为2日龄-6月龄。7个家系均发现基因突变，PRRT2基因Sanger测序发现一个家系携带PRRT2基因热点突变c.649dupC；二代测序发现3个家系携带SCN2A基因错义突变（c.2674G〉A/p.V892I、c.2872A〉G/p.M958V和c.2627A〉G/p.N876S），其中c.2872A〉G/p.M958V和c.2627A〉G/p.N876S为未报道的新突变；二代测序发现3个家系携带KCNQ2基因突变，其中错义突变见于2个家系（c.958G〉A/p.V320I和c.998G〉A/p.R333Q），c.958G〉A/p.V320I为未报道的新突变，KCNQ2基因杂合片段缺失见于1个家系，该片段缺失还累及了邻近的CHRNA4基因，缺失范围包括KCNQ2基因和CHRNA4基因的全部外显子。结论BFNIE的致病基因谱包括KCNQ2、SCN2A和PRRT2基因，基因突变检出率高，KCNQ2和SCN2A基因突变在BFNIE中常见。SCN2A基因突变c.2872A〉G/p.M958V和c.2627A〉G/p.N876S及KCNQ2基因突变c.958G〉A/p.V320I为新发现的突变。

Objective To investigate the spectrum of mutations in families with benign familial neonatal-infantile epilepsy （BFNIE）. Methods Clinical data and peripheral blood DNA samples of all BFNIE probands and their family members were collected from Peking University First Hospital between Deeember 2012 and April 2016. Clinical phenotypes of affected members were analyzed. Genomic DNA was extracted from peripheral blood samples with standard protocol. Mutations in PRRT2 were screened using Sanger sequencing. For families that PRRT2 mutations were not detected by Sanger sequencing, candidate gene mutations were further screened by next-generation sequencing for epilepsy. Results A total of 7 families were collected. Of the 30 affected members, 15 were male and 15 were female. The age of epilepsy onset was from 2 days to 6 months. Genetic testing led to the identification of gene mutations in all families. One family had the PRRT2 hotspot mutation （c.649dupC）. Three families had missense SCN2A mutations （c.2674G〉A/p.V892I, c.2872A〉G/p.M958V, and c.2627A〉G/p.N876S）. Both c.2872A〉G/p. M958V and e.2627A〉G/p.N876S were novel SCN2A mutations. Three families had KCNQ2 mutations. Two of them had missense mutations （c.958G〉A/p.V320I and c.998G〉A/p.R333Q）. The KCNQ2 mutation e.958G〉A/p.V320I was novel. One family had a gene deletion of KCNQ2, which also extended to the adjacent gene, CHRNA4; and the deletion involved all the exons of KCNQ2 and CHRNA4. Conclusions Mutations in KCNQ2, SCN2A, and PRRT2 are genetic causes of BFNIE in Chinese families. The detection rate for gene mutations is high in BFNIE families. KCNQ2 and SCN2A mutations are common in BFNIE families. SCN2A mutations （c.2872A〉G/p.M958V and c.2627A〉G/p.N876S） and KCNQ2 mutation （c.958G〉 A/p.V320I） are novel mutations.