OBJECTIVE: To explore the genetic basis for a Chinese pedigree affected with genetic epilepsy with febrile seizures plus (GEFS+). METHODS: Clinical data of the proband and his family members were collected. Following extraction of genomic DNA, the proband was subjected to high-throughput sequencing. Candidate variant was verified by Sanger sequencing of the proband and other family members. RESULTS: The pedigree, including 6 patients with febrile seizures from 3 generations, was diagnosed with typical GEFS+. Among them, 2 had febrile seizures (FS), 1 had febrile seizures plus (FS+), and 3 had febrile seizures with focal seizures. High-throughput sequencing revealed that the proband has carried a heterozygous missense variant of c.4522T>A (p.Tyr1508Asn) of the SCN1A gene. Sanger sequencing confirmed that other five patients and one normal member from the pedigree have also carried the same variant, which yielded a penetrance of 85.7%. CONCLUSION The c.4522T>A (p.Tyr1508Asn) of the SCN1A gene probably underlay the disease in this pedigree. The pattern of inheritance was consistent with autosomal dominant inheritance with incomplete penetrance. Above finding has enriched the variant spectrum of the SCN1A gene.
Epilepsy/genetics* ; Humans ; NAV1.1 Voltage-Gated Sodium Channel/genetics* ; Pedigree ; Phenotype ; Seizures, Febrile/genetics*

OBJECTIVE: To analyze the clinical features and genetic variants in two patients with Dravet syndrome (DS). METHODS: Peripheral blood samples of the children and their parents were collected for the extraction of genomic DNA and high-throughput sequencing. Suspected variants were confirmed by Sanger sequencing. RESULTS: By high-throughput sequencing, the two children were found to respectively harbor a c.2135delC frameshifting variant in exon 12 and a c.1522G>T nonsense variant in exon 10 of the SCN1A gene. Both variants were predicted to be pathogenic by bioinformatic analysis. Based on the American College of Medical Genetics and Genomics standards and guidelines, the c.2135delC and c.1522G>A variants of the SCN1A gene were predicted to be pathogenic (PVS1+ PS2+ PM2+ PP3). CONCLUSION The variants of the SCN1A gene probably underlay the DS in the patients. Above finding has enriched the variant spectrum and enabled genetic counseling for their families.
Epilepsies, Myoclonic/genetics* ; Genomics ; Humans ; Infant ; Mutation ; NAV1.1 Voltage-Gated Sodium Channel/genetics* ; Pedigree ; Spasms, Infantile/genetics*

OBJECTIVETo determine the type and frequency of SCN1A deletions and duplications among patients with Dravet syndrome (DS).

METHODSFor DS patients in which no mutations of the SCN1A gene were detected by PCR-DNA sequencing, SCN1A deletions and duplications were detected by multiplex ligation-dependent probe amplification (MLPA).

RESULTSIn 680 DS patients, 489 had SCN1A mutations identified by PCR-DNA sequencing. In 191 patients who were negative for the SCN1A PCR-DNA sequencing, 15 (15/191, 7.9%) were detected with heterozygous SCN1A deletions or duplications, which included 14 (14/15, 93.3%) SCN1A deletions and 1 SCN1A duplication. There were 13 types of mutations, including whole SCN1A deletions in 3 patients, partial SCN1A deletions in 11 patients and partial SCN1A duplications in one patient. By testing the parents, 14 mutations were found to be de novo. For the remaining case, no SCN1A deletion or duplication was found in the mother, while the father was not available.

CONCLUSIONApproximately 8% of Chinese patients who were negative for SCN1A mutation by PCR-sequencing have SCN1A deletions or duplications. The MLPA analysis should be considered as an important strategy for such patients. SCN1A deletions are more common than SCN1A duplications among DS patients, and the most common types are whole SCN1A deletions. The majority of SCN1A deletions or duplications are de novo.

Epilepsies, Myoclonic ; genetics ; Female ; Gene Deletion ; Gene Duplication ; Humans ; Infant ; Male ; Multiplex Polymerase Chain Reaction ; NAV1.1 Voltage-Gated Sodium Channel ; genetics

Voltage-gated sodium (Na) channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Na channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Na channels, with Na1.1 and Na1.5 each harboring more than 400 mutations. Na channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Na channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Ca) channel Ca1.1 provides a template for homology-based structural modeling of the evolutionarily related Na channels. In this Resource article, we summarized all the reported disease-related mutations in human Na channels, generated a homologous model of human Na1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Na channels, the analysis presented here serves as the base framework for mechanistic investigation of Na channelopathies and for potential structure-based drug discovery.
Animals ; Calcium Channels, L-Type ; chemistry ; genetics ; metabolism ; Channelopathies ; genetics ; metabolism ; Humans ; Mutation ; NAV1.1 Voltage-Gated Sodium Channel ; chemistry ; genetics ; metabolism ; NAV1.5 Voltage-Gated Sodium Channel ; chemistry ; genetics ; metabolism ; NAV1.7 Voltage-Gated Sodium Channel ; chemistry ; genetics ; metabolism ; Protein Domains ; Rabbits ; Structure-Activity Relationship

OBJECTIVETo analyze the parental origin of de novo SCN1A mutations in 22 patients with Dravet syndrome (DS).

METHODSClinical data and peripheral blood DNA of the patients and their parents were collected. SCN1A gene mutation was screened by polymerase chain reaction (PCR) and Sanger sequencing. For de novo mutations, allele-specific-PCR (AS-PCR) was used to determine their parental origins. Should the mutations be of paternal origin, semen specimen for their fathers was analyzed using PCR and Sanger sequencing for SCN1A gene mutations.

RESULTSThe parental origins of 22 de novo mutations were successfully determined by AS-PCR. Nineteen (86.4%) of the mutations had a paternal origin and 3 (13.6%) had a maternal origin. For those with a paternal origin, semen samples from 9 fathers were analyzed, but no mutation was found.

CONCLUSIONThe majority of de novo SCN1A mutations were of paternal origin. The same mutation was not found in semen samples from the fathers, for which deep sequencing may be necessary.

Adult ; Alleles ; Base Sequence ; Child, Preschool ; Epilepsies, Myoclonic ; genetics ; Female ; Humans ; Infant ; Male ; Molecular Sequence Data ; Mutation ; NAV1.1 Voltage-Gated Sodium Channel ; genetics ; Pedigree

OBJECTIVE: To investigate whether single nucleotide polymorphisms (SNPs) of rs2298771 and rs3812718 of the sodium channel α-subunit type 1 (SCN1A) gene affect the efficacy of carbamazepine (CBZ) treatment for seizures in Chinese Han epileptic patients. METHODS: SNP rs2298771 and rs3812718 of the SCN1A gene from 628 patients were genotyped. CBZ monotherapy was administered to the subjects with new-onset partial seizures. The efficacy was defined as the decrease in the number of seizures. Four semi-quantitative levels were used to assess the efficacy: seizure-free (SF), >75% seizure decrease (SD), 50%-75% SD, and <50% SD in the number of seizures compared with patients' initial conditions. RESULTS: After the 12 month treatment with CBZ monotherapy, the rate of SF patients with G allele of the SNP rs2298771 was significantly lower than that in patients with the AA genotype (P=0.003). The heterozygote and homozygote of the G allele at SNP rs2298771 predicted the low SF rate (OR=2.101, 95% CI 1.289-3.425). Marginal significance was observed between the dichotomous efficacy of SF and non-SF in 3 partial seizure types (P=0.028). CONCLUSION rs2298771 is significantly associated with the efficacy of CBZ monotherapy in Chinese Han epileptic patients.
Alleles ; Asian Continental Ancestry Group ; Carbamazepine ; therapeutic use ; Epilepsy ; Genotype ; Humans ; NAV1.1 Voltage-Gated Sodium Channel ; genetics ; Polymorphism, Single Nucleotide ; Seizures ; drug therapy ; genetics

OBJECTIVETo study SCN1A gene mutations and their inheritance in patients with Dravet syndrome(DS), and to analyze the phenotypes of their family members and genotype-phenotype correlations.

METHODSGenomic DNA was extracted from peripheral blood samples from 181 DS patients and their parents. Phenotypes of affected members were analyzed. SCN1A gene mutations were screened using PCR-DNA sequencing and multiplex ligation-dependent probe amplification (MLPA) RESULTS: SCN1A gene mutations were identified in 128 patients (70.7%), which included 60 missense mutations (46.9%), 55 truncation mutations (43.0%), 10 splice site mutations (7.8%), and 3 cases with SCN1A gene fragment deletions or duplications(2.3%). Five patients (3.9%) had mutations inherited from one of their parents. One father has carried a somatic mutation mosaicism (C373fsx378). For the 5 parents carrying a mutation, 1 had febrile seizures, 2 had febrile seizures plus, 1 had afebrile generalized tonic-clonic seizures, whilst 1 was normal.

CONCLUSIONThe mutation rate of SCN1A in DS patients is about 70%. Most mutations are of missense and truncation mutations. Only a few patients have carried fragment deletions or duplications. Most SCN1A mutations are de novo, only a few were inherited from the parents. SCN1A mutations carried by the parents can be in the form of mosaicism. The phenotypes of parents with SCN1A mutations are either mild or normal.

Amino Acid Sequence ; Base Sequence ; Epilepsies, Myoclonic ; genetics ; Female ; Genetic Association Studies ; Genotype ; Humans ; Male ; Molecular Sequence Data ; Mutation ; NAV1.1 Voltage-Gated Sodium Channel ; genetics ; Pedigree ; Phenotype ; Sequence Alignment

OBJECTIVETo summarize the phenotypes and identify SCN1A mutations in families with generalized epilepsy with febrile seizures plus (GEFS(+)), and analyze the genotype- phenotype correlations in GEFS(+) families.

METHODGenomic DNA was extracted from peripheral blood lymphocytes of the proband and other available members in the GEFS(+) families. The phenotypes of the affected members were analyzed. The coding regions and flanking intronic regions of the SCN1A gene were screened for mutations using PCR and direct DNA sequencing.

RESULTIn 39 GEFS(+) families, there were 196 affected members, ranging from 2 to 22 affected members in each family. Their phenotypes included febrile seizures (FS) in 92(46.9%), febrile seizures plus (FS(+)) in 62(31.6%), FS or FS(+) with partial seizures in 12(6.1%), afebrile generalized tonic-clonic seizures (AGTCS) in 11(5.6%), myoclonic atonic epilepsy in 8(4.1%), Dravet syndrome in 2(1.0%), childhood absence epilepsy in 1 (0.5%), FS(+) with myoclonic seizures in 1(0.5%), AGTCS and myoclonic seizures in 1 (0.5%), partial seizures in 1 (0.5%), unclassified seizures in 5 (2.6%). Four families were found with SCN1A mutations, including three families with missense mutation (N935H, R101Q, G1382R) and one family with truncation mutation (C373fsx378). In three families with missense mutations, the phenotypes include FS, FS(+), FS(+) with partial seizures, and AGTCS. In one family with truncation mutation, the phenotypes included FS, FS(+), and Dravet syndrome. The mother of proband in the family with missense mutation (R101Q) and the father of proband in the family with truncation mutation (C373fsx378) were both somatic mosaicism. Both of their phenotypes were FS(+).

CONCLUSIONThe most common phenotypes of GEFS(+) were FS and FS(+), followed by the FS/FS(+) with partial seizures and AGTCS. The most severe phenotype was Dravet syndrome. SCN1A mutation rate in GEFS(+) was about 10%. Missense mutation was common in GEFS(+) families, few with truncation mutation. Few members of GEFS(+) families had somatic mosaicism of SCN1A mutations and their phenotypes were relatively mild.

Base Sequence ; Child, Preschool ; DNA Mutational Analysis ; Epilepsies, Myoclonic ; genetics ; Epilepsy, Generalized ; genetics ; Female ; Genotype ; Humans ; Infant ; Male ; Molecular Sequence Data ; Mutation ; genetics ; Mutation, Missense ; NAV1.1 Voltage-Gated Sodium Channel ; genetics ; Pedigree ; Phenotype ; Seizures, Febrile ; genetics

OBJECTIVETo study the clinical and genetic characteristics of generalized epilepsy with febrile seizures plus (GEFS).

METHODSData of two probands of the disease were collected through outpatient clinic. DNA was extracted from peripheral blood leukocytes using RelaxGene Blood DNA System. Twenty-six exons of SCN1A were amplified by polymerase chain reaction (PCR), the PCR products were screened by denaturing high performance liquid chromatography (DHPLC), then the abnormal fragments were sequenced by Sanger method in order to find the mutations of SCNIA gene.

RESULTS(1) There were 28 affected individuals in the two families of GEFS+ (14 males and 14 females). Febrile seizures (FS) were present in 7 cases, febrile seizures plus (FS+) in 6 cases, FS+ and absence seizures in 1 case, FS+ and myoclonic seizures in 1 case, uncertain type in 13 cases. No severe phenotype was seen. Bilineal inheritance occured in one GEFS+ family. (2) A samesense mutation (c. 1212A > G) of SCN1A gene was found in the proband and an unaffected individual of pedigree B of GEFS.

CONCLUSIONS(1) GEFS+ is a syndrome with the characteristics of heterogeneous clinical phenotypes; bilineal inheritance suggests the possibility of complex inheritance with additive gene effects. (2) Our study failed to provide evidence supporting a causal relation between the SCN1A mutation and the etiologic gene in the GEFS+ family B, which indicates that GEFS+ has the phenotypic and genotypic heterogeneity.

Adolescent ; Child ; Child, Preschool ; DNA Mutational Analysis ; Epilepsy, Generalized ; complications ; genetics ; Female ; Genetic Testing ; Genotype ; Humans ; Infant ; Male ; NAV1.1 Voltage-Gated Sodium Channel ; Nerve Tissue Proteins ; genetics ; Pedigree ; Phenotype ; Seizures, Febrile ; complications ; genetics ; Sodium Channels ; genetics

Epilepsy ; genetics ; Humans ; Mutation ; NAV1.1 Voltage-Gated Sodium Channel ; Nerve Tissue Proteins ; genetics ; Sodium Channels ; genetics