Idiopathic epilepsies with seizures precipitated by fever and SCN1A abnormalities

PURPOSE: SCN1A is the most clinically relevant epilepsy gene, most mutations lead to severe myoclonic epilepsy of infancy (SMEI) and generalized epilepsy with febrile seizures plus (GEFS+). We studied 132 patients with epilepsy syndromes with seizures precipitated by fever, and performed phenotype-genotype correlations with SCN1A alterations. METHODS: We included patients with SMEI including borderline SMEI (SMEB), GEFS+, febrile seizures (FS), or other seizure types precipitated by fever. We performed a clinical and genetic study focusing on SCN1A, using dHPLC, gene sequencing, and MLPA to detect genomic deletions/duplications on SMEI/SMEB patients. RESULTS: We classified patients as: SMEI/SMEB = 55; GEFS+= 26; and other phenotypes = 51. SCN1A analysis by dHPLC/sequencing revealed 40 mutations in 37 SMEI/SMEB (67%) and 3 GEFS+ (11.5%) probands. MLPA showed genomic deletions in 2 of 18 SMEI/SMEB. Most mutations were de novo (82%). SMEB patients carrying mutations (8) were more likely to have missense mutations (62.5%), conversely SMEI patients (31) had more truncating, splice site or genomic alterations (64.5%). SMEI/SMEB with truncating, splice site or genomic alterations had a significantly earlier age of onset of FS compared to those with missense mutations and without mutations (p = 0.00007, ANOVA test). None of the remaining patients with seizures precipitated by fever carried SCN1A mutations. CONCLUSION: We obtained a frequency of 71%SCN1A abnormalities in SMEI/SMEB and of 11.5% in GEFS+ probands. MLPA complements DNA sequencing of SCN1A increasing the mutation detection rate. SMEI/SMEB with truncating, splice site or genomic alterations had a significantly earlier age of onset of FS. This study confirms the high sensitivity of SCN1A for SMEI/SMEB phenotypes.     

Phenotypes and genotypes in epilepsy with febrile seizures plus

In the last several years, mutations of sodium channel genes, SCN1A, SCN2A, and SCN1B, and GABA(A) receptor gene, GABRG2 were identified as causes of some febrile seizures related epilepsies. In 19 unrelated Japanese families whose probands had febrile seizures plus or epilepsy following febrile seizures plus, we identified 2 missense mutations of SCN1A to be responsible for the seizure phenotypes in two FS+ families and another mutation of SCN2A in one family. The combined frequency of SCN1A, SCN2A, SCN1B, SCN2B, and GABRG2 mutations in Japanese patients with FS+ was 15.8%. One family, which had R188W mutation in SCN2A, showed digenic inheritance, and another modifier gene was thought to take part in the seizure phenotype. The phenotypes of probands were FS+ in 5, FS+ and partial epilepsy in 10, FS+ and generalized epilepsy in 3, and FS+ and unclassified epilepsy in 1. We proposed the term epilepsy with febrile seizures plus (EFS+), because autosomal-dominant inheritance in EFS+ might be rare, and most of EFS+ display a complex pattern of inheritance, even when it appears to be an autosomal-dominant inheritance. There is a possibility of simultaneous involvement of multiple genes for seizure phenotypes.     

Novel de novo splice-site mutation of SCN1A in a patient with partial epilepsy with febrile seizures plus

This report describes a 4-year-old male patient experienced prolonged febrile seizures after 1 year of age, multiple febrile seizures and complex partial seizures with secondary generalization. The gene encoding voltage-gated sodium channel alpha1-subunit: SCN1A analysis revealed a heterozygous de novo one-point mutation (IVS16+2 T>C) at a splice-acceptor site. This mutation was inferred to cause truncation of the alpha1-subunit molecule and, thereby, a loss of channel function. To date, truncation mutation has been found exclusively in patients with severe myoclonic epilepsy in infancy (SMEI), although only missense mutations have been found in generalized epilepsy with febrile seizures plus (GEFS+), partial epilepsy with FS+, FS+, and FS. The patient's phenotype is consistent with that of partial epilepsy with FS+, rather than SMEI, including borderline SMEI (SMEB). We present the first case report of partial epilepsy with FS+ associated with a truncation mutation of SCN1A. The possibility exists for concomitant involvement of multiple genes other than SCN1A for seizure phenotypes.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

Partial and generalized epilepsy with febrile seizures plus and a novel SCN1A mutation.

BACKGROUND: Generalized epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant syndrome characterized by febrile seizures (FS) and a variety of afebrile generalized seizure types. GEFS+ has previously been linked to mutations in two genes encoding the voltage-gated sodium channel alpha-subunit (SCN1A) and beta1-subunit (SCN1B). We studied a large family with FS and partial as well as generalized seizure types. METHODS: All but two living affected family members were interviewed and examined. Information on deceased affected family members was sought. EEG for 11 affected family members and one unaffected family member were obtained. Genetic linkage analysis and mutation screening of SCN1A were performed on blood samples from 16 affected individuals and their first-degree relatives. RESULTS: There were 27 affected family members; 18 were alive at the time of the study. All affected family members had FS; seven had FS only, and 19 also had afebrile seizures. Eleven individuals continued to have FS beyond 6 years of age. FS were complex in 12 family members, usually with prolonged duration. The index patient had right temporal lobe epilepsy and hippocampal sclerosis. Four other patients had strong historical evidence of temporal lobe epilepsy, and three others had nonlocalizing evidence of partial epilepsy. Pedigree analysis indicated autosomal dominant transmission. All affected individuals who were tested and one asymptomatic individual had a sodium channel mutation of SCN1A, an A-->C transversion at nucleotide 3809 resulting in the substitution of lysine 1270 by threonine in the D3/S2 segment (designated as K1270T). CONCLUSIONS: Our findings indicate that partial epilepsy preceded by FS can be associated with sodium channel mutations and may represent a variant of GEFS+.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

Autosomal dominant epilepsy with febrile seizures plus with missense mutations of the (Na+)-channel alpha 1 subunit gene, SCN1A

Evidence that febrile seizures have a strong genetic predisposition has been well documented. In families of probands with multiple febrile convulsions, an autosomal dominant inheritance with reduced penetrance is suspected. Four candidate loci for febrile seizures have been suggested to date; FEB1 on 8q13-q21, FEB2 on 19p, FEB3 on 2q23-q24, and FEB4 on 5q14-15. A missense mutation was identified in the voltage-gated sodium (Na(+))-channel beta 1 subunit gene, SCN1B at chromosome 19p13.1 in generalized epilepsy with the febrile seizures plus type 1 (GEFS+1) family. Several missense mutations of the (Na(+))-channel alpha 1 subunit (Nav1.1) gene, SCN1A were also identified in GEFS+2 families at chromosome 2q23-q24.3. The aim of this report is precisely to describe the phenotypes of Japanese patients with novel SCN1A mutations and to reevaluate the entity of GEFS+. Four family members over three generations and one isolated (phenotypically sporadic) case with SCN1A mutations were clinically investigated. The common seizure type in these patients was febrile and afebrile generalized tonic-clonic seizures (FS+). In addition to FS+, partial epilepsy phenotypes were suspected in all affected family members and electroencephalographically confirmed in three patients of two families. GEFS+ is genetically and clinically heterogeneous, and associated with generalized epilepsy and partial epilepsy as well. The spectrum of GEFS+ should be expanded to include partial epilepsies and better to be termed autosomal dominant epilepsy with febrile seizures plus (ADEFS+).     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

家族性婴儿重症肌阵挛癫(癎)患儿电压门控性钠通道α1亚基基因的遗传特征

目的 探讨家族性婴儿重症肌阵挛癫(癎)(SME)患儿电压门控性钠通道α1亚基(SCNIA)基因的遗传特征.方法 对我院诊断的具有热性惊厥或癫(癎)家族史的SME患儿及其亲属进行临床资料及外周血标本收集,提取DNA,PCR方法扩增SCNIA基因外显子,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)筛查,对发现"异源峰"者进行测序分析.结果 具有热性惊厥或癫(癎)家族史的SME患儿14例,其中一级亲属具有阳性病史者5例,2例存在SCNIA基因突变,为遗传性突变(c.4284+2T>C和c.1216G>T);二级亲属具有阳性病史者9例,2例存在SCNIA突变,为新生突变.结论 SCN1A基因是SME的重要致病基因,具有相同基因遗传基础的个体可以表型不同.应把一级亲属具有热性惊厥或癫(癎)病史的SME患者作为SCN1A遗传性突变筛查的重点,有助于发现遗传性SME.     

Sodium and potassium channel dysfunctions in rare and common idiopathic epilepsy syndromes

Mutations in the SCN1A gene are found in up to 80% of individuals with severe myoclonic epilepsy of infancy (SMEI), and mutations in KCNQ2 and KCNQ3 were identified in benign familial neonatal convulsions (BFNC) as well as in single families with Rolandic epilepsy (RE) and idiopathic generalized epilepsies (IGE). This paper summarizes recent findings concerning sodium (SCN1A) and potassium channel (KCNQ2 and KCNQ3) dysfunctions in the pathogenesis of rare and common idiopathic epilepsies (IE). SMEI, severe idiopathic generalized epilepsy of infancy (SIGEI), and myoclonic–astatic epilepsy (MAE) are rare IE. Because of some semeiologic overlap, a comparative analysis of the SCN1A gene performed in 20 patients with MAE and in 18 with SIGEI. This revealed mutations in three subjects with SIGEI only. Since BFNC are over-represented in families with RE, a mutational analysis was performed in 58 families with RE with and without BNFC. This revealed functionally relevant mutations in two index cases with BNFC, and three missense mutations (one resulting in a significantly reduced potassium current amplitude) in three patients with RE, but without BNFC. One KCNQ3 missense variant was also detected in eight out of 455 IGE patients but not in 454 controls, and a silent KCNQ2-SNP was found over-represented in both epilepsy samples. These findings confirm that mutations in the SCN1A gene are mainly involved in the pathogenesis of SMEI, rarely in that of SIGEI, and are commonly not found in patients with MAE. They also demonstrate that sequence variations of the KCNQ2 and KCNQ3 genes may contribute to the etiology of common IE syndromes.     

SCN1A mutation analysis in myoclonic astatic epilepsy and severe idiopathic generalized epilepsy of infancy with generalized tonic-clonic seizures

Severe myoclonic epilepsy in infancy (SMEI), severe idiopathic generalized epilepsy of infancy (SIGEI) with generalized tonic clonic seizures (GTCS), and myoclonic astatic epilepsy (MAE) may show semiological overlaps. In GEFS+ families, all three phenotypes were found associated with mutations in the SCN1A gene. We analyzed the SCN1A gene in 20 patients with non-familial myoclonic astatic epilepsy -- including 12 probands of the original cohort used by Doose et al. in 1970 to delineate MAE. In addition, 18 patients with sporadic SIGEI -- mostly without myoclonic-astatic seizures -- were analyzed. Novel SCN1A mutations were found in 3 individuals. A frame shift resulting in an early premature stop codon in a now 35-year-old woman with a borderline phenotype of MAE and SIGEI (L433fsX449) was identified. A splice site variant (IVS18 + 5 G --> C) and a missense mutation in the conserved pore region (40736 C --> A; R946 S) were detected each in a child with SIGEI. We conclude that, independent of precise syndromic delineation, myoclonic-astatic seizures are not predictive of SCN1A mutations in sporadic myoclonic epilepsies of infancy and early childhood.     

Absence of mutations in major GEFS+ genes in myoclonic astatic epilepsy

Myoclonic astatic epilepsy (MAE) is a genetically determined condition of childhood onset characterized by multiple generalized types of seizures including myoclonic astatic seizures, generalized spike waves and cognitive deterioration. This condition has been reported in a few patients in generalized epilepsy with febrile seizures plus (GEFS+) families and MAE has been considered, like severe myoclonic epilepsy of infancy (SMEI), to be a severe phenotype within the GEFS+ spectrum. Four genes have been identified in GEFS+ families, but only three (SCN1A, SCNlB, GABRG2) were found in MAE patients within GEFS+ families. We analysed these three genes in a series of 22 sporadic patients with MAE and found no causal mutations. These findings suggest that MAE, unlike SMEI, is not genetically related to GEFS+. Although MAE and SMEI share the same types of seizures, only SMEI patients are sensitive to fever. This is probably its main link to GEFS+. A different family of genes is likely to account for MAE.     

Mosaic SCN1A mutation in familial severe myoclonic epilepsy of infancy

PURPOSE: Mutations of the alpha1 subunit sodium channel gene (SCN1A) cause severe myoclonic epilepsy of infancy (SMEI). Mutations of SCN1A have been found in 40 to 100% of SMEI patients and are de novo in the majority of individuals. METHODS: We studied two sisters with SMEI and their father with febrile seizures. RESULTS: SCN1A screening revealed a splice-site mutation in both sisters. The mutation was inherited from their father in whom, however, a mosaicism was found, with 37% of ectodermal derivative cells carrying the mutation. CONCLUSIONS: In this family, a SCN1A mosaic mutation correlated with the milder phenotype, whereas the full heterozygous mutation caused SMEI. The possibility of mosaic mutations must, therefore, also be taken into account for genetic counseling and determining the recurrence risk in patients with SMEI.