GABRG2 gene polymorphisms in Egyptian children with simple febrile seizures

GABRG2 C588T Polymorphism Is Associated with Idiopathic Generalized Epilepsy but Not with Antiepileptic Drug Resistance in Pakistani Cohort

Idiopathic generalized epilepsy (IGE) is the most prevalent type of epilepsy with genetic origin. Mutations in ion channel genes have been identified as a common cause of IGE. Several studies have reported various epilepsy risk variants of GABRG2 (gamma-aminobutyric acid type A receptor subunit gamma2 subunit) gene in different ethnic groups, but the results are inconsistent. The purpose of this case-control research is to determine if GABRG2 polymorphisms contribute to IGE susceptibility and antiepileptic drug resistance in Pakistani population. For this purpose, we genotyped exon2, exon5 (C540T and C588T), exon7 (T813C), exon8 (K289M), and exon9 of GABRG2 gene by restriction fragment length polymorphism and Sanger's sequencing in 87 drug-responsive idiopathic generalized epilepsy patients, 55 drug-resistant epilepsy patients, and 83 healthy controls. Restriction fragment length polymorphism (RFLP) and sequencing results indicated only C588T polymorphism in the studied subjects. The comparison of genotypic and allelic frequencies showed significant differences between IGE patients and control groups (P = 0.008 and odds ratio = 4.2) and nonsignificant association of C588T polymorphism in antiseizure medication-resistant patients (P = 0.9). Our findings showed that C588T polymorphism of GABRG2 is a risk variant for IGE in Pakistani population. Further studies are required to validate the results.

Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants

OBJECTIVE

This study aimed to obtain a comprehensive understanding of the genetic and phenotypic aspects of GABRG2-related epilepsy and its prognosis and to explore the potential prospects for personalized medicine.

METHODS

Through a multicenter collaboration in China, we analyzed the genotype-phenotype correlation and antiseizure medication (ASM) of patients with GABRG2-related epilepsy. The three-dimensional protein structure of the GABRG2 variant was modeled to predict the effect of GABRG2 missense variants using PyMOL 2.3 software.

RESULTS

In 35 patients with GABRG2 variants, 22 variants were de novo, and 18 variants were novel. The seizure onset age was ranged from 2 days after birth to 34 months (median age: 9 months). The seizure onset age was less than 1 year old in 22 patients (22/35, 62.9%). Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%). Other clinical features included fever-sensitive seizures (91.4%), cluster seizures (57.1%), and developmental delay (45.7%). Neuroimaging was abnormal in 2 patients, including dysplasia of the frontotemporal cortex and delayed myelination of white matter. Twelve patients were diagnosed with febrile seizures plus, eleven with epilepsy and developmental delay, two with Dravet syndrome, two with developmental and epileptic encephalopathy, two with focal epilepsy, two with febrile seizures, and four with unclassified epilepsy. The proportions of patients with missense variants in the extracellular region and the transmembrane region exhibiting developmental delay were 40% and 63.2%, respectively. The last follow-up age ranged from 11 months to 17 years. Seizures were controlled in 71.4% of patients, and 92% of their seizures were controlled by valproate and/or levetiracetam.

CONCLUSION

The clinical features of GABRG2-related epilepsy included seizure onset, usually in infancy, and seizures were fever-sensitive. More than half of the patients had cluster seizures. Phenotypes of GABRG2-related epilepsy were ranged from mild febrile seizures to severe epileptic encephalopathies. Most patients with GABRG2 variants who experienced seizures had a good prognosis. Valproate and levetiracetam were effective treatments for most patients.

Genetic Polymorphism of GABRG2 rs211037 is Associated with Drug Response and Adverse Drug Reactions to Valproic Acid in Chinese Southern Children with Epilepsy

Background

Valproic acid (VPA) is recommended as a first-line treatment for children with epilepsy. GABRG2 polymorphism is found to be associated with epilepsy susceptibility and therapeutic response of anti-seizure medications (ASM); however, the role of GABRG2 in VPA treatment still remains unknown.

Objective

The purpose of this study was to explore the association of GABRG2 gene polymorphism with the drug response and adverse drug reactions (ADRs) related to VPA.

Methods

A retrospective study including 96 Chinese children with epilepsy treated by VPA was carried out. The ADRs were collected during VPA therapy and GABRG2 rs211037 in enrolled patients was genotyped using Sequenom MassArray system. A network pharmacological analysis involved protein–protein interaction and enrichment analysis was constructed to investigate the potential targets and pathways of GABRG2 on VPA-related ADRs.

Results

Among 96 patients, 41 individuals were defined as seizure together with 49 patients with seizure-free and 6 patients unclassified. Carriers of homozygote GABRG2 rs211037 CC genotype exhibited seizure-free to VPA (P = 0.042), whereas those with CT genotype showed seizure. Furthermore, CC genotype had predisposition to digestive ADRs (P = 0.037) but was a protective factor for VPA-associated weight gain (P = 0.013). Ten key genes related to digestive ADRs and weight gain induced by VPA were identified by network pharmacological analysis and mainly involved in “GABAergic synaptic signaling”, “GABA receptor signaling”, and “taste transduction” pathways/processes through enrichment analysis.

Conclusion

This study revealed that GABRG2 variation exerted a predictable role in the efficacy and safety of VPA treatment for Chinese children with epilepsy.

Association between GABRG2 rs211037 polymorphism and idiopathic generalized epilepsies: a meta-analysis

Background

We performed this meta-analysis to investigate the association between GABRG2 rs211037polymorphism and the risk for idiopathic generalized epilepsies (IGEs).

Methods

Medline, Embase, Cochrane Library and Chinese National Knowledge Infrastructure (CNKI) databases were searched for eligible studies (until May 5, 2020) on the association between GABRG2 rs211037 polymorphism and IGE. The odds ratios were calculated using a fixed or random model in STATA 15.0 software. Subgroup analyses for ethnicity, age, source of controls, type of seizure syndrome and therapeutic responses were conducted.

Results

We found no significant associations between GABRG2 rs211037 polymorphism and the susceptibility to IGEs. In addition, no significant association was detected between GABRG2 rs211037 polymorphism and drug resistance in IGE patients. The results did not change after stratification by Asian population, healthy controls, children, juvenile myoclonic epilepsy, and childhood absence epilepsy.

Conclusion

The current studies indicated that the GABRG2 rs211037 polymorphism was not related to susceptibility or drug resistance of IGE. Further well-designed studies are needed to verify the results.

Analysis of GABRG2 C588T polymorphism in genetic epilepsy and evaluation of GABRG2 in drug treatment

Epilepsy is a common disorder with complex inheritance, and its treatment is very unsatisfactory. An association between the GABRG2 C588T polymorphism and genetic generalized epilepsy has been studied by several genetic association studies. However, these results were inconsistent, and the role of GABRG2 in epilepsy treatment remains unknown. To evaluate the role of GABRG2 in epilepsy, we performed meta-analysis, expression quantitative trait loci analysis, protein-protein interaction analysis, and drug-gene interaction analysis. The combined results indicated that the GABRG2 C588T polymorphism was associated with genetic generalized epilepsy risk under dominant and allelic models (odds ratio [OR] = 1.25, 95% confidence interval [CI] = 1.02-1.54, p = 0.03, I²  = 0% and OR = 1.21, 95% CI = 1.03-1.42, p = 0.02, I²  = 20%, respectively). In the Asian population, we also found similar results under dominant and allelic models (OR = 1.93, 95% CI = 1.18-3.16, p = 0.009, I²  = 0% and OR = 1.69, 95% CI = 1.20-2.37, p = 0.003, I²  = 11%, respectively). We first found that the GABRG2 C588T polymorphism regulates GABRG2 expression in human brain tissues and that the protein encoded by GABRG2 interacts with targets of approved antiepileptic drugs (AEDs). Interestingly, we also found that GABRG2 itself interacts with approved AEDs. Taken together, the results indicate that the C588T polymorphism might alter the GABA_A receptor by modulating GABRG2 gene expression, resulting in increased risk for epilepsy, and that GABRG2 may be a potential therapeutic target for epilepsy.

Association between GABRG2 rs211037 polymorphism and febrile seizures: a meta-analysis

Background

Emerging evidence has implied that the GABRG2 gene play a role in the mechanism of febrile seizure (FS), however, the relationship between GABRG2 rs211037 polymorphism and the risk of FS remains controversial. This meta-analysis was conducted to investigate the relationship of GABRG2 rs211037 polymorphism with the susceptibility to FS.

Methods

MEDLINE, Embase, Cochrane Library and CNKI databases were searched (until April 6, 2019) for eligible studies on the relationship between GABRG2 rs211037 polymorphism and FS. We calculated the odds ratios (ORs) by a fixed or random model with the STATA 15.0 software. Subgroup analyses for the ethnicity, the source of the control, and age and sex matching of controls were conducted.

Results

A total of 8 studies consisting of 775 FS patients and 5162 controls were included in this study. Based on the overall data, he GABRG2 rs211037 polymorphism was not significantly associated with the risk of FS (TT + CT vs CC: OR = 0.95, 95%CI 0.64–1.41, P = 0.80). Notably, the GABRG2 rs211037 variant was significantly associated with decreased risk of FS in Asian populations (TT vs CT + CC: OR = 0.63, 95%CI 0.45–0.88, P = 0.006), but increased risk in Caucasian populations (CT vs CC: OR = 1.56, 95%CI 1.14–2.15, P = 0.006). Significant associations were also detected when healthy controls out of the whole controls were employed for comparison (TT vs CT + CC: OR = 0.59, 95% CI 0.45–0.77, P < 0.001) and when data from studies with age- and sex-matched controls were used (TT + CT vs CC: OR = 0.60, 95% CI 0.43–0.86, P = 0.001).

Conclusion

The GABRG2 rs211037 polymorphism may decrease the risk of FS in Asian populations, while increasing the risk in Caucasian populations. Further well-designed studies with large sample sizes are essential to verify the conclusions in other ethnicities.

A Review of Febrile Seizures: Recent Advances in Understanding of Febrile Seizure Pathophysiology and Commonly Implicated Viral Triggers

Febrile seizures are one of the commonest presentations in young children, with a 2-5% incidence in Western countries. Though they are generally benign, with rare long-term sequelae, there is much to be learned about their pathophysiology and risk factors. Febrile seizures are propagated by a variety of genetic and environmental factors, including viruses and vaccines. These factors must be taken into consideration by a clinician aiming to assess, diagnose and treat a child presenting with fevers and seizures, as well as to explain the sequelae of the febrile seizures to the concerned parents of the child. Our article provides an overview of this common childhood condition, outlining both the underlying mechanisms and the appropriate clinical approach to a child presenting with febrile seizures.

The genetic variant "C588T" of GABARG2 is linked to childhood idiopathic generalized epilepsy and resistance to antiepileptic drugs

PURPOSE

Previous studies have suggested that GABARG2 (Gamma-Aminobutyric acid type A Receptor Gamma 2 subunit) could be a gene of interest in genetic epilepsy; through possible associations with increased epilepsy susceptibility or resistance to antiepileptic drugs. The present study was designed to explore whether the GABARG2 C588 T (rs211037) genetic variant predicts susceptibility to epilepsy and pharmacoresistance among Egyptian children with Idiopathic Generalized Epilepsy (IGE).

METHODS

A cohort of 210 Egyptian children was divided into two groups for this case-control study: group (I) included 100 children with IGE, group (II) comprised of 110 paediatric healthy controls. PCR-RFLP was used to amplify the C588 T polymorphism of the GABARG2 gene, which was digested with APOI restriction enzymes.

RESULTS

There was a higher frequency of the TT genotype (P = 0.004) and T allele (P = 0.002) of the C588 T polymorphism of the GABARG2 gene in patients than controls. Besides, there was a substantial increase of the T allele among drug-resistant patients compared with those responding to antiepileptic drugs (P = 0.00015). Children with the C allele were four times more likely to be responsive to antiepileptic drugs than non-C-allele-carriers.

CONCLUSION

The C588 T polymorphism of GABARG2 is associated with an increased risk of developing childhood IGE and may modulate patients' response to antiepileptic drugs.

Serum Interleukin-6 Levels in Children with Febrile Seizures

OBJECTIVE

To compare levels of Interleukin-6 (IL-6) in children with febrile seizures and febrile controls.

METHODS

Study conducted in a tertiary-care hospital in Northern India from November 2013 to April 2015, enrolling 160 children (80 each with febrile seizures and febrile controls), aged 6 - 60 months. Serum IL-6 estimated by ELISA method. Iron study done as per standard technique. All the cases of febrile seizure were followed up at 1 week, 3 months and 6 months for recurrence of seizures.

RESULTS

The mean serum IL-6 levels in children with febrile seizures was 62.0 (63.9) pg/mL and febrile controls was 86.9 (70.6) pg/mL (P=0.025).

CONCLUSION

Serum IL-6 levels were significantly lower in children with febrile seizures as compared to febrile controls.

GABRG2 C588T gene polymorphisms might be a predictive genetic marker of febrile seizures and generalized recurrent seizures: a case-control study in a Romanian pediatric population

INTRODUCTION

This case-control study aimed to assess two single nucleotide polymorphisms of the gene encoding the GABRG2 protein - GABRG2 (3145 G>A) and GABRG2 rs 211037 Asn196Asn (C588T) - in a cohort of pediatric patients from Romania, and evaluate their possible impact on drug-resistant forms of generalized epilepsy and recurrent febrile seizures.

MATERIAL AND METHODS

One hundred and fourteen children with idiopathic generalized epilepsy (group 1) or febrile seizures (group 2) were compared to 153 controls. Peripheral blood samples were assessed using polymerase chain reaction-restriction fragment length polymorphism analysis, with results interpreted based on the disappearance of a restriction site in the C allele (122 bp) compared to the T allele (100 bp + 22 bp).

RESULTS

A significant association was found with the TT homozygous genotype and T allele for both febrile seizures and epilepsy for the C588T locus, while GABRG2 G>A 3145 showed no significant association with any type of seizure. The TT homozygous genotype of GABRG2 Asn196Asn polymorphism was more frequent in patients with a history of febrile seizures (p = 0.0001), without a significant association identified for GABRG2-G>A 3145. Composite analysis showed associations with epilepsy for CC-AG (p = 0.02) and CT-AG (p = 0.007) with the CC-AA combination as reference.

CONCLUSIONS

C588T polymorphism of the GABRG2 gene might be a predictive genetic marker in triggering febrile convulsions. GABRG2 rs211037 TT homozygotes and T allele variants have an increased risk for developing febrile seizures. Recurrent crises and repeated episodes of seizures are more frequent in the GABRG2 Asn196Asn TT genotype polymorphism, with a 45 and 8 times higher risk of developing idiopathic generalized epilepsy and recurrent febrile seizures, respectively.

Generation of Febrile Seizures and Subsequent Epileptogenesis

Febrile seizures (FSs) occur commonly in children aged from 6 months to 5 years. Complex (repetitive or prolonged) FSs, but not simple FSs, can lead to permanent brain modification. Human infants and immature rodents that have experienced complex FSs have a high risk of subsequent temporal lobe epilepsy. However, the causes of FSs and the mechanisms underlying the subsequent epileptogenesis remain unknown. Here, we mainly focus on two major questions concerning FSs: how fever triggers seizures, and how epileptogenesis occurs after FSs. The risk factors responsible for the occurrence of FSs and the epileptogenesis after prolonged FSs are thoroughly summarized and discussed. An understanding of these factors can provide potential therapeutic targets for the prevention of FSs and also yield biomarkers for identifying patients at risk of epileptogenesis following FSs.

Genetic variants of synaptic vesicle and presynaptic plasma membrane proteins in idiopathic generalized epilepsy

BACKGROUND

The aim of this study was to analyze the role of the genetic variants of two synaptic vesicle proteins (VAMP2 and Synaptotagmin XI) and two presynaptic plasma membrane proteins (Syntaxin 1A and SNAP-25) in patients with idiopathic generalized epilepsy (IGE).

METHOD

Eighty-five patients with IGE and 93 healthy subjects were included in the study. We analyzed the functional polymorphisms of VAMP2, Synaptotagmin XI, Syntaxin 1A and SNAP-25 genes with polymerase chain reaction and restriction fragment length polymorphism methods.

RESULTS

In the patients with IGE, significant differences alleles and genotypes of 26 bp Ins/Del polymorphism of the VAMP2 gene and the 33-bp promoter region of Synaptotagmin XI were observed, however no associaton was found regarding Intron 7 rs1569061 of Syntaxin 1A gene, MnlI rs3746544 and DdeI rs1051312 polymorphisms of SNAP-25 gene compared with healthy subjects. Carriers of the C allele of Synaptotagmin XI had worse measures compared with the T allele of Synaptotagmin XI. In the haplotype analysis, the frequency of the T alleles of rs1569061 and of the C alleles of the 33-bp promoter region of Synaptotagmin XI was found to be significantly higher in patients with IGE as compared with the healthy subjects.

CONCLUSION

The genetic variations of VAMP2, Synaptotagmin XI might be indication of the relationship between these genes and IGE.