Lack of SCN1A mutations in familial febrile seizures

PURPOSE: Mutations in the voltage-gated sodium channel subunit gene SCN1A have been associated with febrile seizures (FSs) in autosomal dominant generalized epilepsy with febrile seizures plus (GEFS+) families and severe myoclonic epilepsy of infancy. The present study assessed the role of SCN1A in familial typical FSs. METHODS: FS families were selected throughout a collaborative study of the Italian League Against Epilepsy. For each index case, the entire coding region of SCN1A was screened by denaturant high-performance liquid chromatography. DNA fragments showing variant chromatograms were subsequently sequenced. RESULTS: Thirty-two FS families accounting for 91 affected individuals were ascertained. Mutational analysis detected a single coding variant (A3169G) on exon 16. The extended analysis of all family members and 78 normal controls demonstrated that A3169G did not contribute to the FS phenotype. CONCLUSIONS: Our study demonstrated that SCN1A is not frequently involved in common FSs and suggested the involvement of specific FS genes.     

Sodium channel SCN1A and epilepsy: Mutations and mechanisms

Mutations in a number of genes encoding voltage‐gated sodium channels cause a variety of epilepsy syndromes in humans, including genetic (generalized) epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS, severe myoclonic epilepsy of infancy). Most of these mutations are in the SCN1A gene, and all are dominantly inherited. Most of the mutations that cause DS result in loss of function, whereas all of the known mutations that cause GEFS+ are missense, presumably altering channel activity. Family members with the same GEFS+ mutation often display a wide range of seizure types and severities, and at least part of this variability likely results from variation in other genes. Many different biophysical effects of SCN1A‐GEFS+ mutations have been observed in heterologous expression systems, consistent with both gain and loss of channel activity. However, results from mouse models suggest that the primary effect of both GEFS+ and DS mutations is to decrease the activity of GABAergic inhibitory neurons. Decreased activity of the inhibitory circuitry is thus likely to be a major factor contributing to seizure generation in patients with GEFS+ and DS, and may be a general consequence of SCN1A mutations.     

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.     

A novel SCN2A mutation in family with benign familial infantile seizures

Benign familial infantile seizures (BFIS) is a clinical entity characterized by focal seizures with or without secondary generalization, occurring mostly in clusters, and usually first seen between 4 and 8 months of life. Psychomotor development is normal, and seizures usually resolve within the first year of life. BFIS is a genetically heterogenous condition with loci mapped to chromosomes 19 and 16. Mutations in the voltage-gated sodium channel alpha2 subunit (SCN2A) gene on chromosome 2 were recently identified in families affected by neonatal and infantile seizures (benign familial neonatal-infantile seizures, BFNIS) with typical onset before 4 months of life. The identification of SCN2A mutations in families with only infantile seizures indicated that BFNIS and BFIS show overlapping clinical features. We report a pedigree showing three affected individuals over three generations. All subjects experienced clusters of focal seizures with or without secondary generalization and onset between 4 and 12 months of life. Response to antiepileptic drugs and the outcome were good. No subjects had other forms of epilepsy later in the life. Neonatal or febrile seizures did not occur in the family. Genetic study in this family revealed a novel heterozygous mutation c.3003 T>A in the SCN2A gene. Comparative analysis of different sodium channel alpha subunits indicates that the mutated residue is highly conserved throughout the evolution, suggesting an important functional role for this domain. Additional families with the infantile form of benign familial seizures should be investigated to corroborate that BFIS and BFNIS may share the same genetic abnormality.     

SCN2A mutations and benign familial neonatal-infantile seizures: the phenotypic spectrum

Mutations of the sodium channel subunit gene SCN2A have been described in families with benign familial neonatal-infantile seizure (BFNIS). We describe two large families with BFNIS and novel SCN2A mutations. The families had 12 and 9 affected individuals, respectively, with phenotypes consistent with BFNIS. Two mutations were discovered in SCN2A (E430Q; I1596S). Both families had individuals with neonatal onset but the typical age of onset was in the early infantile period (mean 3.0 months). One mutation positive individual, with an otherwise typical clinical pattern, had seizures beginning at 13 months. Two individuals with SCN2A mutations were identified with seizures in later life. In each family a single individual with infantile seizures was mutation negative and thus represented phenocopies. This study extends the age range of presentation of BFNIS, confirms that neonatal and early infantile onsets are characteristic, and emphasizes the role of molecular diagnosis to confirm the etiology.     

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.     

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.     

Infantile epilepsy associated with mosaic 2q24 duplication including SCN2A and SCN3A

Epilepsies can be caused by specific genetic anomalies or by non-genetic factors, but in many cases the underlying cause is unknown. Mutations in the SCN1A and SCN2A genes are reported in childhood epilepsies; in particular SCN1A was found mutated in patients with Dravet syndrome and with generalized epilepsy with febrile seizures plus (GEFS+). In this paper we report a patient presenting with an atypical epileptic syndrome whose phenotype partially overlaps both Dravet syndrome and benign familial neonatal-infantile seizures (BFNIS). Array-CGH analysis suggested the presence of a mosaic duplication (about 12Mb) at the level of chromosome 2q23.3q24.3 involving SCN2A and SCN3A genes. Additional analyses (radiolabeled RFLP and quantitative PCR) confirmed the mosaicism of the duplication. We suggest that the array-CGH analysis is mandatory for children presenting with epilepsy and psycho-motor retardation even without dysmorphisms or other clinical features suggesting a specific genetic/epileptic syndrome. The analysis must nevertheless be performed taking into account the possibility of a mosaicism.     

Variable epilepsy phenotypes associated with a familial intragenic deletion of the SCN1A gene

Deletions and duplications/amplifications of the α1-sodium channel subunit (SCN1A) gene occur in about 12% of patients with Dravet syndrome (DS) who are otherwise mutation-negative. Such genomic abnormalities cause loss of function, with severe phenotypes, reproductive disadvantage and, therefore, sporadic occurrence. Inherited mutations, occurring in ～5% of patients with DS, are usually missense; transmission occurs from a mildly affected parent exhibiting febrile seizures (FS) or the generalized epilepsy with febrile seizures plus (GEFS+) spectrum. We identified an intragenic SCN1A deletion in a three-generation, clinically heterogeneous family. Sequence analysis of SCN9A, a putative modifier, ruled out pathogenic mutations, variants, or putative disease-associated haplotype segregating with phenotype severity. Intrafamilial variability in phenotype severity indicates that SCN1A loss of function causes a phenotypic spectrum in which seizures precipitated by fever are prominent and schematic syndrome subdivisions would be inappropriate. SCN1A deletions should be ruled out even in individuals with mild phenotypes.     

GEFS+ is not related to the most common mutations of SCN1B,SCN1A and GABRG2 in two Tunisian families

The objective was to investigate whether the described mutations of the SCN1A, SCN1B and GABRG2 genes are associated to generalised epilepsy with febrile seizure plus (GEFS+) in two Tunisian families. We performed a genetic study of two multigenerational Tunisian families with GEFS+ spectrum. The molecular analysis included a PCR amplification of SCN1B, SCN1A and GAGRG2 exons, then a screening of the known SCN1B, SCN1A and GABRG2 gene mutations by direct sequencing. The data excluded the involvement of all known published mutations. However, an insertion of a T nucleotide at a heterozygous state within the intron 12 of the SCN1A gene has been identified in two probands and their parents. Our results corroborate the genetic heterogeneity of GEFS+ predominantly in epilepsy patients of different countries and ethnic groups.