Dravet综合征的SCNlA基因突变

目的筛查9个Dravet综合征患者的钠通道α1（5CN1A）基因，明确该综合征与SCN1A基因的关系。方法总结9个中国人Dravet综合征患者的临床特点，收集Dravet综合征患者血样，应用变性高效液相色谱（DHPLC）技术对该综合征患者进行SCN1A基因全部26个外显子筛查，对发现异常洗脱峰者进行测序并分析结果。结果编号为EP91的先证者经DHPLC筛查发现SCNIA基因26号外显子有双峰，经测序证实26号外显子发生错义突变．造成1765位氨基酸-苯丙氨酸突变为亮氨酸（Phel 765Leu），该突变为杂合突变。结论中国人Dravet综合征与．SCN1A基因突变有一定的关系。     

部分性癫(癎)伴热性惊厥附加症家系中的SCN1A基因嵌合突变

目的 筛查一个部分性癫伴热性惊厥附加症(partial epilepsy with febrile seizures plus,PEFS+)家系中的钠通道α1基因(voltage-gated sodium channel α1-subunit,SCN1A)及其遗传特性.方法 总结一个PEFS+家系中2例患者及其父亲的临床特点,应用变性高效液相色谱(denaturing high performance liquid chromtography,DHPLC)技术筛查SCN1A全部26个外显子,发现有异常洗脱峰者进行直接测序,对直接测序未能证实突变的再进行焦磷酸测序.结果 先证者及其同父异母姐姐均为PEPS+患者,他们在SCN1A基因第26号外显子发现有相同的杂合突变A5768G,并导致编码的氨基酸改变Q1923R,其父亲儿时频繁出现热性惊厥(febrile seizures,FS),后自然痊愈,直接测序未发现异常,进一步用焦磷酸测序则发现该位点存在嵌合突变(突变量为25%).结论 SCN1A基因突变可导致部分性癫.PEFS+可遗传,而携带致病基因者可因体内发生嵌合突变,致病基因含量偏低导致临床症状轻微.     

同卵双生的界限型婴儿重症肌阵挛癫(癎)患者中的钠通道α1基因新突变

目的 筛查一对同卵双胞胎界限型婴儿重症肌阵挛癫(癎)(borderland severe myoclonic epilepsy of infancy,SMEB)患儿的钠通道α1(sodium channel α1-subunit,SCN1A)基因并探讨其临床特性.方法 总结这对同卵双生子患者的临床特点,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)技术筛查SCN1A基因全部26个外显子,对发现有异常洗脱峰者再进行直接测序.结果 这对孪生姐妹患者均具有典型SMEB的临床特点,她们在SCN1A基因第26号外显子被发现有相同的杂合突变(c.5348C>T),并导致编码的氨基酸改变(A1783E),为国际上首次发现该位点突变.结论 临床表型相似的SMEB同卵双胞胎存在相同位点的SCN1A基因突变,证实SMEB与婴儿重症肌阵挛癫(癎)同样是基因异常引起的疾病,而且基因与临床表型密切相关.     

家族性高钾型周期性麻痹的SCN4A基因突变

目的　筛查1个高钾型周期性麻痹(hyperkalemicperiodicparalysis, hyperKPP)家系的SCN4A基因,明确该病与SCN4A基因的关系。方法　总结1个hyperKPP家系中7例患者的临床特点,应用变性液相色谱(denaturinghighperformanceliquidchromatography,DHPLC)技术筛查SCN4A基因全部24个外显子,对发现异常洗脱峰者进行连锁分析并测序。结果　该家系具有典型hyperKPP临床特征,但无肌强直。先证者经DHPLC筛查发现在外显子13、23及24存在杂合二倍体。测序及连锁分析证实位于外显子13的碱基替换引起氨基酸序列改变(Thr704Met);外显子23的碱基替换虽引起氨基酸序列改变(Asp1376Asn)与疾病连锁,但进一步研究显示其为一良性多态;外显子24的碱基替换为同义突变。结论　该家族性hyperKPP与SCN4A基因相关,并由最常见的突变Thr704Met引起。     

家族性低钾型周期性麻痹基因型和表型分析

研究背景分析一中国汉族家族性低钾型周期性麻痹家系的致病基因和相关临床资料。方法采用DNA序列技术对先证者(Ⅲ3)进行CACNA1S、SCN4A、KCNE3全基因组筛查,针对检测到的变异进一步检测家系中其他患者和无症状家系成员是否存在相同基因突变,经对临床资料分析以确定相关基因突变是否为致病性突变基因。结果先证者(Ⅲ3)及家系中其他患者(Ⅱ1、Ⅲ4、Ⅳ3)均检测到CACNA1S基因IVS25-194C/T突变,而无症状家系成员(Ⅲ1)未检测到该突变;该家系成员(除Ⅰ1)均检测到SCN4A基因IVS18-130G/A突变,该位点位于内含子区域且有症状和无症状家系成员同时出现;先证者(Ⅲ3)和无症状家系成员(Ⅲ1)同时检测到SCN4A基因外显子12区域c.1984GA突变,系错义突变(V662I),但家系中其他患者(Ⅱ1、Ⅲ4、Ⅳ3)均未发现该位点突变。结论结合临床资料和生物信息学预测,推测CACNA1S、SCN4A、KCNE3基因突变均非该家系致病性突变基因。但该家系资料丰富了我国原发性低钾型周期性麻痹家系的临床和基因数据库。除KCNE3、CACNA1S和SCN4A基因外,中国低钾型周期性麻痹家系可能存在新的致病基因突变,尚待进一步研究。     

遗传性癫痫伴热性惊厥附加症发病年龄及发作频率与基因型的关系

目的通过对3个北方GEFS+家系的基因定位研究,结合文献检索数据汇总,分析GEFS+家系发病年龄及发作频率与基因型的关系。方法采用连锁分析及DNA测序进行基因定位。采用卡方检验比较SCN1A突变组及无突变组起病年龄及发作频率,计算不同模型预测SCN1A突变家系的敏感度及特异度。结果 3个GEFS+家系均未找到致病基因。数据汇总显示SCN1A突变家系54.8%患者热性发作(FS)发病年龄为12个月内,4岁以上仅占1.9%,单次发作占3.4%,无热发作(AFS)患者69.8%发病于6岁以后,与无SCN1A突变家系差异显著(P<0.01)。发作频率预测SCN1A突变家系敏感度及特异度分别为81.8%和56.3%。结论 GEFS+家系具有高度遗传异质性,多数家系无法找到致病基因。发作频率可作为SCN1A突变家系的预测因子。     

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.     

Adults with a history of possible Dravet syndrome: an illustration of the importance of analysis of the SCN1A gene

Most patients with Dravet syndrome have de novo mutations in the neuronal voltage-gated sodium channel type 1 (SCN1A) gene. We report on two unrelated fathers with severe childhood epilepsy compatible with a possible diagnosis of Dravet syndrome, who both have a child with Dravet syndrome. Analysis of the SCN1A gene revealed a pathogenic mutation in both children. One father exhibited somatic mosaicism for the mutation detected in his son. A relatively favorable cognitive outcome in patients with Dravet syndrome patients may be explained by somatic mosaicism for the SCN1A mutation in brain tissue. A mild form of Dravet syndrome in adult patients is associated with a high recurrence risk and possibly a more severe epilepsy phenotype in their offspring.     

A homozygous mutation of voltage‐gated sodium channel βI gene SCN1B in a patient with Dravet syndrome

Dravet syndrome is a severe form of epileptic encephalopathy characterized by early onset epileptic seizures followed by ataxia and cognitive decline. Approximately 80% of patients with Dravet syndrome have been associated with heterozygous mutations in SCN1A gene encoding voltage‐gated sodium channel (VGSC) α_I subunit, whereas a homozygous mutation (p.Arg125Cys) of SCN1B gene encoding VGSC β_I subunit was recently described in a patient with Dravet syndrome. To further examine the involvement of homozygous SCN1B mutations in the etiology of Dravet syndrome, we performed mutational analyses on SCN1B in 286 patients with epileptic disorders, including 67 patients with Dravet syndrome who have been negative for SCN1A and SCN2A mutations. In the cohort, we found one additional homozygous mutation (p.Ile106Phe) in a patient with Dravet syndrome. The identified homozygous SCN1B mutations indicate that SCN1B is an etiologic candidate underlying Dravet syndrome.     

The incidence of SCN1A‐related Dravet syndrome in Denmark is 1:22,000: A population‐based study from 2004 to 2009

Dravet syndrome is a severe infantile‐onset epileptic encephalopathy associated with mutations in the sodium channel alpha‐1 subunit gene SCN1A. We aimed to describe the incidence of Dravet syndrome in the Danish population. Based on a 6‐year birth cohort from 2004 to 2009, we propose an incidence of 1:22,000, which is higher than what has been established earlier. We identified 17 cases with SCN1A mutation–positive Dravet syndrome. Fifteen patients were found, by conventional Sanger sequencing. Two additional patients with clinical Dravet syndrome, but without a detectable SCN1A mutation by Sanger sequencing, were diagnosed with a SCN1A mutation after using a targeted next‐generation sequencing gene panel.     

A screening test for the prediction of Dravet syndrome before one year of age

PURPOSE: Our aim was to develop a screening test to predict Dravet syndrome before the first birthday based on the clinical characteristics of infants and the SCN1A mutation analysis. METHODS: Ninety-six patients who experienced febrile seizures before the age of one were enrolled. The patients were divided into two groups-the Dravet syndrome group (n = 46) and the non-Dravet syndrome group (n = 50). We compared the clinical characteristics before one year of age of the two groups. We analyzed all coding exons of the SCN1A gene by the direct sequencing method. Scores from 0 to 3 were assigned to each risk factor based on the odds ratio and p-value. RESULTS: An age of onset of febrile seizure or= 5, and prolonged seizures lasting more than 10 min. were regarded as significant risk factors for Dravet syndrome. Other factors highly predictive of this syndrome were hemiconvulsions, partial seizures, myoclonic seizures, and hot water-induced seizures. A total clinical score of six or above was the cutoff value indicating a high risk of Dravet syndrome. SCN1A missense and truncated mutations were detected significantly more often in the Dravet syndrome group than in the non-Dravet syndrome group. DISCUSSION: This simple screening test was designed to be used by general pediatricians. It could help to predict Dravet syndrome before one year of age. If the sum of the clinical risk score is >or= 6, then the performance of an SCN1A mutation analysis is recommended.     

Molecular genetics of Dravet syndrome

Before the advent of molecular genetics, the nature of Dravet syndrome remained largely obscure, and arguments in favour of either an acquired origin, such as the occurrence of Dravet syndrome after vaccination, or an inherited origin, such as the occurrence of epilepsy in relatives, were formulated. In 2001 we demonstrated that the majority of Dravet patients have a genetic cause due to loss-of-function mutations in the SCN1A gene. Understandably, since this syndrome severely affects reproductive fitness, these mutations almost exclusively arise de novo, with the rare exceptions of mosaic mutations in a non-affected transmitting parent. Besides classical Sanger sequencing, mutation analysis of the SCN1A gene also requires a method that allows the detection of genomic rearrangements (MAQ, MLPA), since microdeletions or whole gene deletions also result in Dravet syndromes. Depending on the series reported and their recruitment strategies, the yield of SCN1A mutations detected varied from 50 to 80%, implying that other genes or factors must be involved in these 'SCN1A-negative Dravet patients'. Recently mutations in some other genes have been described in these genuine Dravet patients who do not carry an SCN1A mutation. The second most important Dravet-associated gene is PCDH19.These patients initially may have all characteristics of Dravet syndrome but may later run a somewhat different course.     

Two mild cases of Dravet syndrome with truncating mutation of SCN1A

Background

SCN1A is the gene that codes for the neuronal voltage-gated sodium-channel alpha-subunit 1. It is generally considered that an SCN1A truncating mutation causes the severe phenotype of Dravet syndrome.

Low long-term efficacy and tolerability of add-on rufinamide in patients with Dravet syndrome

In this retrospective European multicenter study we evaluated the efficacy and tolerability of rufinamide in patients with Dravet syndrome and refractory seizures. Twenty patients were included; in 16 patients a SCN1A mutation was detected. The responder rate after 6 months was 20%, and after 34 months, 5%. The retention rate was 45% after 6 months and 5% after 34 months. Rufinamide treatment was stopped because of aggravation of seizures (30%), no effect (45%), and side effects (10%). The efficacy and long-term retention rate were low in our patients with Dravet syndrome and refractory seizures, far lower than in patients with Lennox-Gastaut syndrome; one-third of our patients experienced seizure aggravation. Therefore, rufinamide does not seem to be a suitable option for long-term treatment in patients with Dravet syndrome.     

Missense mutation of the sodium channel gene SCN2A causes Dravet syndrome

Mutations of the gene encoding the α2 subunit of the neuronal sodium channel, SCN2A, have been found in benign familial neonatal-infantile seizures (BFNIS). In Dravet syndrome, only one nonsense mutation of SCN2A was identified, while hundreds of mutations were found in the paralogue gene, SCN1A, which encodes the α1 subunit. This study examines whether SCN2A mutations are associated with Dravet syndrome. We screened for mutations of SCN1A, SCN2A and GABRG2 (the gene encoding γ2 subunit of the GABA_A receptor) in 59 patients with Dravet syndrome and found 29 SCN1A mutations and three missense SCN2A mutations. Among the three, one de novo SCN2A mutation (c.3935G>C: R1312T) identified in a patient was thought to affect an arginine residue in a voltage sensor of the channel and hence, to be pathogenic. This finding suggests that both nonsense mutations and missense SCN2A mutations cause Dravet syndrome.     

Musicogenic seizures in Dravet syndrome

Dravet syndrome is an epileptic encephalopathy characterized by multiple types of seizures. We report the first case of musicogenic reflex seizures in a 7‐year‐old male with a mutation in the SCN1A gene causing Dravet syndrome. Reflex seizures have been reported in patients with Dravet syndrome provoked by body temperature elevation, looking at visual patterns, or under intermittent photic stimulation. The case we report widens the spectrum of reflex seizures recorded in patients with Dravet syndrome. Cortical hyperexcitability of genetic origin could explain the tendency of these patients to experience reflex seizures.     

Supraventricular Tachycardia During Status Epilepticus in Dravet Syndrome: A Link Between Brain and Heart?

BackgroundThe possibility that epileptic seizures and arrhythmias are different clinical manifestations of a common channelopathy is an interesting but unproved hypothesis. Patients with Dravet syndrome show heart rate variability and affected individuals with arrhythmias have also been documented. The possibility that a genetic mutation affecting sodium channel functions may predispose to both Dravet syndrome and arrhythmogenic disorders is an interesting hypothesis.Patient PresentationWe describe a 5-month-old girl with Dravet syndrome who presented with paroxysmal supraventricular tachycardia during status epilepticus. She presented to the hospital the first time with afebrile tonic-clonic seizures and then several subsequent times with status epilepticus confirmed with electroencephalography. During two of these episodes she also exhibited paroxysmal supraventricular tachycardia. She received propofol for status epilepticus and adenosine for the arrhythmia. A clinical and genetic (de novo mutation of a sodium channel, SCN1A) diagnosis of Dravet syndrome was made.ConclusionsOur patient supports the hypothesis that SCN1A mutation might have a role as a common substrate to both epilepsy and cardiac arrhythmia. More studies are needed to better assess genetic, cardiac, respiratory, and autonomic dysfunction in patients with Dravet syndrome.