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

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*

Epilepsy is a group of disorders characterized by recurrent seizures. The etiologies of idiopathic epilepsy commonly have a genetic basis. Gene mutations causing several of the inherited epilepsies have been mapped. In this review, the authors summarize the available information on the genetic basis of human epilepsies and epilepsy syndromes, emphasizing how genetic defects may correlate with the pathophysiological mechanisms of brain hyperexcitability and gene defects can lead to epilepsy by altering multiple and diverse aspects of neuronal function.
Epilepsy ; genetics ; Humans ; KCNQ2 Potassium Channel ; Mutation ; NAV1.1 Voltage-Gated Sodium Channel ; Nerve Tissue Proteins ; genetics ; Potassium Channels ; genetics ; Potassium Channels, Voltage-Gated ; Receptors, Nicotinic ; genetics ; Research ; trends ; Research Design ; Sodium Channels ; genetics ; Voltage-Gated Sodium Channel beta-1 Subunit

Epilepsy is one of the most common and debilitating neurological diseases that affects more than 40 million people worldwide. Genetic factors contribute to the pathogenesis of epilepsy. Molecular genetic studies have identified 15 disease-causing genes for epilepsy. The majority of the genes encode ion channels, including voltage-gated potassium channels KCNQ2 and KCNQ3, sodium channels SCN1A, SCN2A, and SCN1B, chloride channels CLCN2, and ligand-gated ion channels CHRNA4, CHRNB2, GABRG2, and GABRA1. Interestingly, non-ion channel genes have also been identified as epilepsy genes, and these genes include G-protein-coupled receptor MASS1/VLGR1, GM3 synthase, and proteins with unknown functions such as LGI1, NHLRC1, and EFHC1. These studies make genetic testing possible in some patients, and further characterization of the identified epilepsy genes may lead to the development of new drugs and new treatments for patients with epilepsy.
Chloride Channels ; genetics ; Epilepsies, Myoclonic ; genetics ; Epilepsy ; genetics ; Epilepsy, Absence ; genetics ; Humans ; KCNQ2 Potassium Channel ; genetics ; KCNQ3 Potassium Channel ; genetics ; NAV1.1 Voltage-Gated Sodium Channel ; NAV1.2 Voltage-Gated Sodium Channel ; Nerve Tissue Proteins ; genetics ; Sodium Channels ; 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*

Epilepsies, Myoclonic ; genetics ; Humans ; Infant ; Infant, Newborn ; Molecular Biology ; NAV1.1 Voltage-Gated Sodium Channel ; Nerve Tissue Proteins ; genetics ; Sodium Channels ; genetics

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

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

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

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