【摘要】 目的探讨全面性癫痫伴热性惊厥附加症(generalized epilepsy with febrile seizuresplus,GEFS+)的临床特点与分子遗传学特征。方法收集1个 GEFS+家系所有成员的血样标本,选择3种候选基因(SCN1B、SCN1A、GABRG2)附近的11个微卫星标记物 D19S414、D19S220、D19S902、D2S156、D2S142、D2S2330、D2S335、D2S364、D5S436、D5S422和 D5S400,应用 PCR 得到扩增产物片段,根据相应产物大小的不同,得到每个样本的基因型;用连锁分析软件的 MLINK 程序计算每个标记的 LOD 值,根据两点间的 LOD 值判断连锁关系,探讨 GEFS+的可能致病基因与染色体19q13.1、2q24以及5q3101-q33.1区域的连锁关系。连锁分析限定性定位后再进行 GABRG2基因突变分析。结果 (1)GEFS+家系临床特征:家系成员4代共20人。第Ⅱ～Ⅳ代中患者6例(男女各3例);发作表型为热性惊厥(FS)1例、热性惊厥附加症(FS+)3例、FS+伴失神发作1例,发作类型不详1例,未见严重发作类型。(2)GEFS+基因连锁分析结果:①D2S335因不能进行基因分型,给予舍弃;②D19S和 D2S 多个 LOD 值小于0,在重组率为0.0时 D19S220、D19S902、D2S364处的 LOD 值均小于-2;D19S414、D2S142、D2S156、D2S2330、D5S422处的 LOD 值小于0,基本可以排除连锁关系;③D5S436、D5S400处的 LOD 值在重组率为0.0时大于-2,但小于3,既不能排除也不能肯定其连锁关系;该家系致病基因与报道的 GEFS+定位区域19q13.1和2q24区域没有连锁关系;与5q31.1-q33.1区域的连锁关系有待于进一步明确。(3)GABRG2基因的测序结果(先证者):显示11外显子一处同义突变(c.1420C>T),未见 GABRG2基因致病突变。结论该 GEFS+家系呈现不同的临床表型,其疾病基因与3种候选基因 SCN1A、SCN1B、GABARG2的突变无关;表明 GFFS+具有表型的异质性与遗传的异质性,其病因学有待进一步研究。更多还原

【Abstract】 Objective To study the clinical and genetic characteristics of a Chinese family with generalized epilepsy with febrile seizures plus(GEFS+).GEFS+ is an autosomal dominant familial syndrome with a complex seizure phenotype caused by mutations in one of 3 voltage-gated sodium channel subunit genes(SCN1 B,SCN1 A,and SCN2A)and the GABAA receptor gamma2 subunit gene(GABRG2). Methods DNA was extracted from peripheral blood leukocytes using phenolchloroform method.We performed linkage analysis on this pedigree.Eleven microsatellite markers spanning the critical regions on chromosomes 19q13.1,2q24,and 5q31.1-q33.1 were genotyped.These markers included D19S414, D19S220,D19S902 for the 19q region,D2S156,D2S142,D2S2330,D2S335 and D2S364 for the 2q region,D5S436,D5S422 and D5S400 for the 5q region.DNA from each sample was amplified for the 11 markers.After polymerase chain reactions(PCR),then the length of the PCR products was judged with the Strategene Eagle Eye Ⅱ automated gel image analyzer.The date of PCR products were analyzed using the software Genescan v311,Genetyper v3.7.After Mendelian checking,the eligible genotyping data were used for linkage analysis.LOD scores were calculated by using MLINK program of LINKAGE v5.1.The LOD scores were calculated at combination rate 0.0,0.1,0.2,0.3,0.4.Mutation analysis of GABRG2 gene was made by means of polymerse chain reaction(PCR)-direct sequencing in the proband and his father. Results(1)As for the clinical characteristics of GEFS+,there were six cases in the family of 20 members over four generations.The phenotypes of febrile seizures(FS)in 1,febrile seizures plus(FS+) in 3;FS+with typical absence were identified respectively in 1,3 and 1 members,and no information for the remaining one individual was available.(2)The genetic linkage analysis among the 11 selected microsatellite markers indicated that①one marker date(D2S335)was omitted due to failed genotyping.② Two-point LOD scores were below zero for the makers D19S414,D2S142,D2S156,D2S2330 and D5S422, and the maximum LOD scores at 0.0 were less than that at-2 for the makers D19S220,D19S902 and D2S364.No evidence showed that the diseases locus was linked to the markers selected above.③For the other two markers D5S436 and D5S400,two-point LOD scores at 0.0 were between 0.5-0.8(>-2,and <3),for which detailed linkage analysis was needed in the future.(3)A synonymous mutation(c.1420C >T)was detected on exon 11 in the mutational analysis of GABRG2.Our results indicate that genomic variations of GABRG2 are not likely to be substantially involved in the etiology of GEFS+in this family. Conclusion Our study fails to provide evidence supporting a causal relation between the SCN1A,SCN1B, GABRG2 mutation and the etiologic genes in this family,which indicates that GEFS+has with phenotypic and genotypic heterogeneity.更多还原