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The mammalian circadian clock located in the suprachiasmatic nucleus (SCN) produces robust daily rhythms including rest-wake. SCN neurons synthesize and respond to γ-aminobutyric acid (GABA), but its role remains unresolved. We tested the hypothesis that γ2-and δ-subunits of the GABAA receptor in the SCN differ in their regulation of synchrony among circadian cells. We used two approaches: 1) shRNA to knock-down (KD) the expression of either γ2 or δ subunits in the SCN or 2) knock-in mice harboring a point mutation in the M2 domains of the endogenous GABAA γ2 or δ subunits. KD of either γ2 or δ subunits in the SCN increased daytime running and reduced nocturnal running by reducing their circadian amplitude by a third. Similarly, δ subunit knock-in mice showed decreased circadian amplitude, increased duration of daily activity, and decreased total daily activity. Reduction, or mutation of either γ2 or δ subunits halved the synchrony among, and amplitude of, circadian SCN cells as measured by firing rate or expression of the PERIOD2 protein, in vitro. Surprisingly, overexpression of the γ2 subunit rescued these phenotypes following KD or mutation of the δ subunit, and overexpression of the δ subunit rescued deficiencies due to γ2 subunit KD or mutation. We conclude that γ2 and δ GABAA receptor subunits play similar roles in maintaining circadian synchrony in the SCN and amplitude of daily rest-wake rhythms, but that modulation of their relative densities can change the duration and amplitude of daily activities. [ABSTRACT FROM AUTHOR]

Objective: To explore the mechanism involved in variable phenotypes of epilepsy models induced by γ‐aminobutyric acid type A γ2 subunit (GABRG2) mutations. Methods: The zebrafish carrying wild‐type (WT) GABRG2, mutant GABRG2(P282S), GABRG2(F343L) and GABRG2(I107T) were established by Tol2kit transgenesis system and Gateway method. Behavioral analysis of different transgenic zebrafish was performed with the DanioVision Video‐Track framework and the brain activity was analyzed by field potential recording with MD3000 Bio‐signal Acquisition and Processing System. The transcriptome analysis was applied to detect the underlying mechanisms of variable phenotypes caused by different GABRG2 mutations. Results: The established Tg(hGABRG2P282S) zebrafish showed hyperactivity and spontaneous seizures, which were more sensitive to chemical and physical epileptic stimulations. Traditional antiepileptic drugs, such as Clonazepam (CBZ) and valproic acid (VPA), could ameliorate the hyperactivity in Tg(hGABRG2P282S) zebrafish. The metabolic pathway was significantly changed in the brain transcriptome of Tg(hGABRG2P282S) zebrafish. In addition, the behavioral activity, production of pro‐inflammatory factors, and activation of the IL‐2 receptor signal pathway varied among the three mutant zebrafish lines. Conclusion: We successfully established transgenic zebrafish epileptic models expressing human mutant GABRG2(P282S), in which CBZ and VPA showed antiepileptic effects. Differential inflammatory responses, especially the SOCS/JAK/STAT signaling pathway, might be related to the phenotypes of genetic epilepsy induced by GABRG2 mutations. Further study will expand the pathological mechanisms of genetic epilepsies and provide a theoretical basis for searching for effective drug treatment. [ABSTRACT FROM AUTHOR]

BACKGROUND: The mechanism mining of Alzheimer’s disease is very important and bioinformatics is an effective prediction technology for the potential targets of Alzheimer’s disease. OBJECTIVE: To screen the genes related to the pathogenesis of Alzheimer’s disease and verify them at the animal level by bioinformatics analysis. METHODS: Differentially expressed genes were screened through the GEO online database. GO/KEGG enrichment analysis was performed using the DAVID online database. A protein-protein interaction network was constructed using the STRING database. Target protein distribution in human was identified using the HPA database. Finally, protein expression was analyzed using immunofluorescence and western blot techniques. RESULTS AND CONCLUSION: Gene chips for Alzheimer’s disease and healthy populations were obtained using GSE48350, a dataset within the GEO online database, and the GEO2R online analysis platform was used to analyze the differentially expressed genes between the two populations, including 42 upregulated genes and 131 down-regulated genes. Results of the GO enrichment analysis suggested that the differentially expressed genes were mainly located in presynaptic, transport vesicles and extracellular vesicles, to mediate biological processes such as neurotransmitter release and synaptic vesicle function. KEGG pathway analysis results showed that differentially expressed genes were mainly enriched in synaptic function-related signaling pathways such as neuroactive ligand-receptor interactions, γ-aminobutyric acid synapses and retrograde endogenous cannabinoid signaling. Based on the protein interaction network, five up-regulated hub genes (CLU, GFAP, CD44, FOS, ANXA1) and five down-regulated hub genes (GABRG2, SYT1, SYN2, KCNC1, SLC32A1) were identified. It was confirmed that the expression of GABRG2, KCNC1, and SLC32A1 in the hippocampal tissue in a mouse model of Alzheimer’s disease were significantly downregulated. To conclude, these three genes can be used as potential genes for the treatment and diagnosis of Alzheimer’s disease and provide important clues for the treatment of Alzheimer’s disease. GABRG2, KCNC1 and SLC32A1 are also co-therapeutic targets for Alzheimer’s disease and epilepsy. [ABSTRACT FROM AUTHOR]

Background: Current evidence suggests that Gamma-aminobutyric acid (GABA) receptors are associated with the occurrence and progression of cerebrovascular diseases. The present study investigated the association between single nucleotide polymorphisms (SNPs) in the Gamma-aminobutyric acid type A receptor gamma2 subunit (GABRG2) gene and ischemic stroke (IS). Methods: A total of 120 healthy volunteers and 187 patients with IS were recruited. Patients underwent complete neurological assessment and classification with the National Institute of Health Stroke Scale (NIHSS) and the Trial of ORG 10172 in Acute Stroke Treatment (TOAST). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze SNP sites in 4 different regions (rs211037, rs418210, rs211035, and rs424740) of the GABRG2 gene. SHEsis online platform was used to assess SNP allele and genotype frequencies. Multivariate logistic regression analysis was performed to identify the risk factors for IS. Results: Univariate analysis showed that the T allele and TT genotype distribution for rs211037 were significantly more frequent in the IS group compared to controls (pallele = 0.01, odds ratio (OR) = 1.673, 95% confidence intervals (CI), 1.119-2.500, pgenotype = 0.03). Furthermore, multivariate logistic regression analysis revealed the TT genotype for rs211037 was an independent risk factor for IS (p = 0.017, OR = 1.925, 95% CI, 1.122--3.303). Age was also found to be an independent risk factor, and the older the age, the higher the risk of IS (p = 0.001, OR = 1.047, 95% CI, 1.020--1.073). Finally, subgroup analysis revealed that patients with the rs211037 TT genotype were associated with a higher NIHSS score (p = 0.03), and that large-artery atherosclerosis (LAA) subtype was predominant in patients with the rs211037 TT genotype (p = 0.042). Conclusions: These findings suggest the rs211037 polymorphism in the GABRG2 gene is an independent risk factor for IS in the Chinese population. GABRG2 could thus be a potential biomarker to assess the risk of IS. [ABSTRACT FROM AUTHOR]

ObjectiveWe aimed to identify genes associated with genetic generalized epilepsy (GGE) by combining large cohorts enriched with individuals with a positive family history. Secondarily, we set out to compare the association of genes independently with familial and sporadic GGE.MethodsWe performed a case-control whole exome sequencing study in unrelated individuals of European descent diagnosed with GGE (previously recruited and sequenced through multiple international collaborations) and ancestry-matched controls. The association of ultra-rare variants (URVs; in 18 834 protein-coding genes) with epilepsy was examined in 1928 individuals with GGE (vs. 8578 controls), then separately in 945 individuals with familial GGE (vs. 8626 controls), and finally in 1005 individuals with sporadic GGE (vs. 8621 controls). We additionally examined the association of URVs with familial and sporadic GGE in two gene sets important for inhibitory signaling (19 genes encoding γ-aminobutyric acid type A [GABAA ] receptors, 113 genes representing the GABAergic pathway).ResultsGABRG2 was associated with GGE (p = 1.8 × 10-5 ), approaching study-wide significance in familial GGE (p = 3.0 × 10-6 ), whereas no gene approached a significant association with sporadic GGE. Deleterious URVs in the most intolerant subgenic regions in genes encoding GABAA receptors were associated with familial GGE (odds ratio [OR] = 3.9, 95% confidence interval [CI] = 1.9-7.8, false discovery rate [FDR]-adjusted p = .0024), whereas their association with sporadic GGE had marginally lower odds (OR = 3.1, 95% CI = 1.3-6.7, FDR-adjusted p = .022). URVs in GABAergic pathway genes were associated with familial GGE (OR = 1.8, 95% CI = 1.3-2.5, FDR-adjusted p = .0024) but not with sporadic GGE (OR = 1.3, 95% CI = .9-1.9, FDR-adjusted p = .19).SignificanceURVs in GABRG2 are likely an important risk factor for familial GGE. The association of gene sets of GABAergic signaling with familial GGE is more prominent than with sporadic GGE.

Background: Previous studies have shown that SLC6A11 and GABRG2 are linked to drug-resistant epilepsy (DRE), although there have been conflicting results in the literature. In this study, we systematically assessed the relationship between DRE and these two genes. Methods: We systematically searched the PubMed, Embase, Cochrane Library, Web of Science, Google Scholar, Wanfang Data, CNKI, and VIP databases. To clarify whether heterogeneity existed between studies, tools such as the Q-test and I2 statistic were selected. According to study heterogeneity, we chose fixedor random-effects models for analysis. We then used the chi-squared ratio to evaluate any bias of the experimental data. Results: In total, 11 trials and 3,813 patients were selected. To investigate the relationship with DRE, we performed model tests on the two genes separately. The results showed that SLC6A11 rs2304725 had no significant correlation with DRE risk in the allele, dominant, recessive, and additive models in a pooled population. However, for the over-dominant model, DRE was correlated with rs2304725 (OR = 1.08, 95% CI: 0.92–1.27, p = 0.33) in a pooled population. Similarly, rs211037 was weakly significantly correlated with DRE for the dominant, recessive, over-dominant, and additive models in a pooled population. The subgroup analysis results showed that rs211037 expressed a genetic risk of DRE in allele (OR = 1.01, 95% CI: 0.76–1.35, p = 0.94), dominant (OR = 1.08, 95% CI: 0.77–1.50, p = 0.65), and additive models (OR = 1.14, 95% CI: 0.62–2.09, p = 0.67) in an Asian population. Conclusion: In this meta-analysis, our results showed that SLC6A11 rs2304725 and GABRG2 rs211037 are not significantly correlated with DRE. However, in the over-dominant model, rs2304725 was significantly correlated with DRE. Likewise, rs211037 conveyed a genetic risk for DRE in an Asian population in the allele, dominant, and additive models. [ABSTRACT FROM AUTHOR]

Angina pectoris is the most common manifestation of coronary heart disease, causing suffering in patients. Electroacupuncture at PC6 can effectively alleviate angina by regulating the expression of genes, whether the alternative splicing (AS) of genes is affected by acupuncture is still unknown. We established a rat model of myocardial ischemia–reperfusion by coronary artery ligation and confirmed electroacupuncture alleviated the abnormal discharge caused by angina pectoris measured in EMG electromyograms. Analysis of the GSE61840 dataset established that AS events were altered after I/R and regulated by electroacupuncture. I/R decreased the expression of splicing factor Nova1 while electroacupuncture rescued it. Further experiments in dorsal root ganglion cells showed Nova1 regulated the AS of the GABRG2, specifically on its exon 9 where an important phosphorylation site is present. In vivo, results also showed that electroacupuncture can restore AS of GABRG2. Our results proved that electroacupuncture alleviates angina results by regulating alternative splicing. [ABSTRACT FROM AUTHOR]

Sleep-related hypermotor epilepsy (SHE) is a focal epilepsy syndrome. The underlying pathophysiology is presumed to be closely related with disruption of GABAergic neurotransmission, which is mainly medicated by γ-aminobutyric acid type A receptor (GABAAR). Thus, it is reasonable to assume that rare GABAAR variants might contribute to the pathogenesis of SHE. To test this hypothesis, we performed next-generation sequencing in 58 SHE patients and analyzed the functional effects of the identified variants in both neuronal and non-neuronal cells using a combination of electrophysiology recordings, western blot, flow cytometry, and confocal microscopy. In our study, we detected three rare variants (NM_198904.2: c.269C > T, p.T90M; NM_198904.2: c.950C > A, p.T317N and NM_198903.2: c.649C > T, p.Q217X) in GABRG2 (MIM:137,164, encoding GABAAR γ2 subunit) in three unrelated patients. Two of the three rare variants were transmitted unaffected maternally (T90M) or unaffected paternally (Q217X), whereas the T317N variant arose de novo. The mother of proband carrying the T90M variant was unaffected and being mosaicism for this variant. Functional analysis showed that T90M and T317N variants decreased GABA-evoked current amplitudes by diverse mechanisms including impaired surface expression, endoplasmic reticulum retention, and channel gating defects. And Q217X variant reduced synaptic clustering and distribution of GABAAR. While a causal role of these variants cannot be established directly from these results, the functional assessment together with the genetic sequencing suggests that these rare GABRG2 variants may constitute genetic risk factors for SHE. Our study further expands the GABRG2 phenotypic spectrum and supports the view that GABAergic neurotransmission participates in the epileptogenesis of SHE. [ABSTRACT FROM AUTHOR]

Jieluan Lu,1 Hanbing Xia,2 Wenzhou Li,2 Xianhuan Shen,1 Huijuan Guo,2 Jianping Zhang,1 Xiaomei Fan2 1Department of Clinical Pharmacology, College of Pharmacy, Jinan University, Guangzhou, 510632, People’s Republic of China; 2Department of Pharmacy, Baoan Women’s and Children’s Hospital, Jinan University, Shenzhen, 518102, People’s Republic of ChinaCorrespondence: Jianping ZhangDepartment of Clinical Pharmacology, College of Pharmacy, Jinan University, 601 W. Huangpu Avenue, Guangzhou, 510632, People’s Republic of ChinaTel +86 20 85220261Email tzhangjp@jnu.edu.cnXiaomei FanDepartment of Pharmacy, Baoan Women’s and Children’s Hospital, Jinan University, 56# Yulv Road, Baoan District, Shenzhen, 518102, People’s Republic of ChinaTel +86 755 27863999Email xmfane@163.comBackground: 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.Keywords: children with epilepsy, GABRG2, gene polymorphism, valproic acid, therapeutic response, adverse drug reactions

Epilepsy is one of the most common neurological disorders with the incidence rate higher in developing states. It is a multifactorial ailment in which genetic diversity along with other factors plays an important role. The objective of this study was to assess the involvement of different risk factors including single nucleotide polymorphisms (SNPs) present in GABRA1 (rs2279020) and GABRG2 (rs211037) genes with the susceptibility to epilepsy in the targeted population. Blood samples of 180 subjects were taken and genotyped through tetra-primer amplification refractory mutation system-polymerase chain reaction technique. The obtained demographic and genotypic data were analyzed through different statistical tools including χ2 (chi-square) test and odds ratio. Parental consanguinity and family history of seizures were observed in a considerable number of cases of this study along with residency in industrial areas. But, no association of rs2279020 (χ2 = 0.900, P = 0.638) and rs211037 (χ2 = 0.045, P = 0.832) was observed with predisposition to epilepsy. However, GG genotype of rs2279020 was observed more in female cases as compared to male cases. Furthermore, TG haplotype was observed to be associated with the increased risk of developing epilepsy (χ2 = 9.097; OR = 2.586; P = 0.002). Genetic models also showed no correlation of the targeted SNPs with the susceptibility to epilepsy. The outcomes of the present study suggested that neither rs211037 nor rs2279020 were associated with increased susceptibility to epilepsy in the targeted population. [ABSTRACT FROM AUTHOR]

Abstract 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.

Pathogenic missense and truncating variants in the GABRG2 gene cause a spectrum of epilepsies, from Dravet syndrome to milder simple febrile seizures. In most cases, pathogenic missense variants in the GABRG2 gene segregate with a febrile seizure phenotype. In this case series, we report a recurrent, de novo missense variant (c0.316 G > A; p.A106T) in the GABRG2 gene that was identified in five unrelated individuals. These patients were described to have a more severe phenotype than previously reported for GABRG2 missense variants. Common features include variable early-onset seizures, significant motor and speech delays, intellectual disability, hypotonia, movement disorder, dysmorphic features and vision/ocular issues. Our report further explores a recurrent pathogenic missense variant within the GABRG2 variant family and broadens the spectrum of associated phenotypes for GABRG2-associated disorders.

Abstract 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

Sleep-related hypermotor epilepsy (SHE) is a focal epilepsy syndrome characterized by seizures that predominantly occur during sleep. The pathogenesis of these seizures remains unclear. We previously detected rare variants in GABRG2 , which encodes the γ 2 subunit of γ-aminobutyric acid type A receptor (GABA A R), in patients with SHE and demonstrated that these variants impaired GABA A R function in vitro. However, the mechanisms by which GABRG2 variants contribute to seizure attacks during sleep remain unclear. In this study, we designed a knock-in (KI) mouse expressing the mouse Gabrg2 T316N variant, corresponding to human GABRG2 T317N variant, using CRISPR/Cas9. Continuous video-electroencephalogram monitoring and in vivo multichannel electrophysiological recordings were performed to explore seizure susceptibility to pentylenetetrazol (PTZ), alterations in the sleep-wake cycle, spontaneous seizure patterns, and synchronized activity in the motor thalamic nuclei (MoTN) and secondary motor cortex (M2). Circadian variations in the expression of total, membrane-bound, and synaptic GABA A R subunits were also investigated. No obvious changes in gross morphology were detected in Gabrg2 T316N/+ mice compared to their wild-type (Gabrg2 +/+ ) littermates. Gabrg2 T316N/+ mice share key phenotypes with patients, including sleep fragmentation and spontaneous seizures during sleep. Gabrg2 T316N/+ mice showed increased susceptibility to PTZ-induced seizures and higher mortality after seizures. Synchronization of the local field potentials between the MoTN and M2 was abnormally enhanced in Gabrg2 T316N/+ mice during light phase, when sleep dominates, accompanied by increased local activities in the MoTN and M2. Interestingly, in Gabrg2 +/+ mice, GABA A R γ2 subunits showed a circadian increase on the neuronal membrane and synaptosomes in the transition from dark phase to light phase, which was absent in Gabrg2 T316N/+ mice. We generated a new SHE mouse model and provided in vivo evidence that rare variants of GABRG2 contribute to seizure attacks during sleep in SHE. • Mice harboring the T316N variant in GABA A R γ 2 subunit are originally constructed. • Gabrg2 T316N/+ knock-in mice have spontaneous seizures mainly occurring during daytime. • NREM sleep is fragmented by brief awakening events in Gabrg2 T316N/+ knock-in mice. • Gabrg2 T316N/+ knock-in mice have enhanced synchronization between MoTN and M2. • Circadian change in membrane γ 2 subunit is absent in Gabrg2 T316N/+ knock-in mice. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

ObjectiveThis 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.MethodsThrough 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.ResultsIn 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.ConclusionThe 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.

The mammalian circadian clock located in the suprachiasmatic nucleus (SCN) produces robust daily rhythms including rest-wake. SCN neurons synthesize and respond to γ-aminobutyric acid (GABA), but its role remains unresolved. We tested the hypothesis that γ2- and δ-subunits of the GABA A receptor in the SCN differ in their regulation of synchrony among circadian cells. We used two approaches: 1) shRNA to knock-down (KD) the expression of either γ2 or δ subunits in the SCN or 2) knock-in mice harboring a point mutation in the M2 domains of the endogenous GABA A γ2 or δ subunits. KD of either γ2 or δ subunits in the SCN increased daytime running and reduced nocturnal running by reducing their circadian amplitude by a third. Similarly, δ subunit knock-in mice showed decreased circadian amplitude, increased duration of daily activity, and decreased total daily activity. Reduction, or mutation of either γ2 or δ subunits halved the synchrony among, and amplitude of, circadian SCN cells as measured by firing rate or expression of the PERIOD2 protein, in vitro. Surprisingly, overexpression of the γ2 subunit rescued these phenotypes following KD or mutation of the δ subunit, and overexpression of the δ subunit rescued deficiencies due to γ2 subunit KD or mutation. We conclude that γ2 and δ GABA A receptor subunits play similar roles in maintaining circadian synchrony in the SCN and amplitude of daily rest-wake rhythms, but that modulation of their relative densities can change the duration and amplitude of daily activities., Competing Interests: Competing interests statement:The authors declare no competing interest.

Febrile seizures (FS) occur in about 2–3% of children aged 3 months to 5 years. Atypical febrile seizures are those with a focal component. Each subsequent febrile attack increases the risk of transformation into epilepsy. After the third febrile seizure, the risk of additional episodes of febrile seizures is already approaching 50%, and the risk of formation of epilepsy is 15.8%. Recent studies show the great contribution of genetic causes to the development of genetic epilepsy with febrile seizures plus (GEFS+). GEFS+ includes a combination of some febrile seizures with subsequent afebrile attack, or recurring febrile seizures after 6 years. The genetic causes of GEFS+ are both monogenic (in particular, disorders in the SCN1B, SCN1A, GABRG2, GABRD, SCN9A, STX1B, HCN1 genes, etc.) and copy number variations. Twin methods suggest that different genetic factors play a role in the case of FS, FS+ and FS with subsequent epilepsy. Genetic cause can be found in about 30% of cases, that affects not only the final diagnosis and prognosis for the patient, but also the prevention of disease in the family. In GEFS+ seizures are usually generalized tonic-clonic, less often myoclonic, myoclonic-atonic seizures, absences and status epilepticus, but sometimes they also describe focal seizures. The clinical picture of patients with GEFS+ varies from family febrile seizures (the least severe cases) to Drave-like syndrome (the most severe cases), although all of them have a predominantly normal level of intellect.

• GABRG2 gene knockout cell model was established using CRISPR/Cas9 system. • GABRG2 KO altered the expression of other GABARs subunits at different temperatures. • Expression of CACNA1 decreased as temperature increased. • Expression of MMP3, MMP9, and MMP13 was upregulated at 37°C. • MAPK and PI3K-Akt signaling pathways were significantly altered. Mutations in γ-aminobutyric acid A receptor (GABA A) subunits and sodium channel genes, especially GABRG2 and SCN1A , have been reported to be associated with febrile seizures (FS) and genetic epilepsy with febrile seizures plus (GEFS+). GEFS+ is a well-known family of epileptic syndrome with autosomal dominant inheritance in children. Its most common phenotypes are febrile seizures often with accessory afebrile generalized tonic-clonic seizures, febrile seizures plus (FS+), severe epileptic encephalopathy, as well as other types of generalized or localization-related seizures. However, the pathogenesis of febrile seizures remains largely unknown. Here, we generated a GABRG2 gene knockout cell line (HT22 GABRG2KO) by applying the CRISPR/Cas9-mediated genomic deletion in HT-22 mouse hippocampal neuronal cell line to explore the function of GABRG2 in vitro. With mRNA-seq, we found significant changes in the expression profiles of several epilepsy-related genes when GABRG2 was knockout, some of them showing temperature-induced changes as well. Kyoto Encyclopedia Gene and Genomic (KEGG) analysis revealed a significant alteration in the MAPK and PI3K-Akt signaling pathways. We also observed an up-regulation of the matrix metalloproteinases (MMPs) family after GABRG2 knockout. Furthermore, the significant decrease in expression of GABRA1 and CACNA1A (but not others) with an increase in temperature is a novel finding. In summary, mutations in the GABA A receptor can lead to a decrease in numbers of receptors, which may cause the impairment of GABAergic pathway signaling. This data has been the first time to reveal that GABRG2 mutations would affect the function of other genes, and based on this finding we hope this work would also provide a new direction for the research of GABRG2 in GEFS+. It also may provide a molecular basis for the severity of epilepsy, and guide the clinical medication for the treatment of the epilepsy focused on the function on GABA A receptors, which, might be a new strategy for genetic diagnosis and targeted treatment of epilepsy. [ABSTRACT FROM AUTHOR]

Background: Hirschsprung disease (HSCR) is a complex and heterogeneous disorder, characterized by a deficit in enteric nervous system. Genome-wide studies implied GABRG2, RELN and NRG3 might be involved in HSCR etiology. Here, we aimed to assess genetic variants in GABRG2, RELN and NRG3 that may confer susceptibility to HSCR and explore genetic interaction networks in HSCR. Methods: Using a strategy that combined case-control study and gene-gene interaction analysis with the MassArray system, we evaluated 24 polymorphisms within GABRG2, RELN and NRG3 in 104 HSCR cases and 151 normal controls of Han Chinese origin. Results: We observed that seven polymorphisms showed statistically significant differences between HSCR subjects and normal controls. For each of the three genes, the haplotypes which combined eight markers were the most significant. Moreover, we recruited SNPsyn, GO enrichment and MDR analyses to interrogate the interactions among GABRG2, RELN, NRG3 and our previous identified PTCH1 gene. Significant interaction networks were found among GABRG2, RELN, and PTCH1. Conclusion: We provide a first indication that common variants of GABRG2, RELN and NRG3 and the GABRG2-RELN-PTCH1 interaction networks might confer altered susceptibility to HSCR in the Han Chinese population, suggesting a potential mechanism underlying HSCR pathogenesis.

Objective: Sunflower syndrome is a unique photosensitive epilepsy, characterized by heliotropism and stereotyped seizures associated with handwaving. These handwaving events (HWE) are thought to be an ictal phenomenon, although current data are contrasting. Photosensitive epilepsy occurs in 2%-5% of the epilepsy forms and several pathogenic gene variants have been associated with photosensitive epilepsy. However, the genetic etiology of Sunflower syndrome remains unknown. Antiseizure medications (ASM) efficacious in treating photosensitive epilepsy are valproic acid (VPA) and levetiracetam (LEV) although some forms, such as Sunflower syndrome, can be drug-resistant., Methods and Results: Here, we report an 8-year-old boy with an early onset of episodes of HWE that was initially categorized as behavioral problems for which risperidone was started. However, the medical history was suggestive of Sunflower syndrome, and subsequent video EEG showed focal mostly temporal and frontotemporal (right and left) epileptiform activity and confirmed the epileptic nature of the HWE. Thus, VPA was started and initially led to seizure frequency reduction. Molecular analyses showed a pathogenic variant in GABRG2 (c.1287G>A p.(Trp429Ter)), which has been associated with photosensitive and generalized epilepsy., Significance: Overall, clinicians worldwide should be cautious by interpreting HWE and/or other tic-like movements, since an epileptic origin cannot be ruled out. A prompt and correct diagnosis can be made by performing a video EEG early on in the diagnostic process when epileptic seizures are part of the differential diagnosis. Even though the genetic etiology of Sunflower syndrome remains poorly understood, this constellation supports further genetic testing since the detection of a pathogenic variant can help in making correct decisions regarding ASM management., (© 2023 International League Against Epilepsy.)

The single nucleotide polymorphisms (SNPs) was used to investigate the distribution of genotypes of SCN2A (rs17183814) c.56 G/A and GABRG2 (rs211037, Asn196Asn) in patients with Neuraldisorders. A total of 50 children with neural disorders and 50 normal control subjects are include in the study. PCR-RFLP is use to identify the G/A polymorphisms of the SCN2A gene on chromosome 2q24 and C/T polymorphisms of the GABRG2 gene on chromosome 5q33. Genotypes and allelic frequencies for the SCN2A and GABRG2 genes in both groups were compared. Results are show that the genotype proportions and allele frequencies for SCN2A c.56 G/A in both patient with ND and control were not significantly different. Proportions of A homozygote, A/G heterozygote and G homozygote for SCN2A c.56 G/A were as follows: in patients with ND, 36%, 46% and 18%, respectively and in control, 24%, 56% and 20%, respectively. The allele A and G frequencies for SCN2A c.56 G®A in patients with ND was 59% and 41%, respectively and in control, 52% and 48%, respectively. But the number of individuals with the GABRG2 (SNP211037)-C/C genotype in patients with Neural disorders is significantly greater compare with that in healthy control subjects (p = 0.0243) and the GABRG2 (SNP211037)-C allele frequency in patients with neural disorders is significantly compare with that in healthy control subjects (p = 0.0172). There are higher significant in Glucose and phosphorus levels, lower significant in sodium and chloride levels. But there are no significant different in serum potassium, calcium and creatinine levels. We found that it’s no relationship between SCN2A, GABRG2 and some biochemical tests in children with neural disorders. These data suggest that the GABRG2 gene might be one of the susceptibility factors for neural disordersand do not suggest that SCN2A c.56 G/A SNPs are susceptibility factors for neural disorders in Al-Samawah city and the fever plays an important role in causing disturbances in electrolyte balance. [ABSTRACT FROM AUTHOR]

Purpose: Next-generation sequencing (NGS) has made genetic testing of patients with epileptic encephalopathies easier - novel variants are discovered and new phenotypes described. Variants in the same gene - even the same variant - can cause different types of epilepsy and neurodevelopmental disorders. Our aim was to identify the genetic causes of epileptic encephalopathies in paediatric patients with complex phenotypes.Methods: NGS was carried out for three patients with epileptic encephalopathies. Detailed clinical features, brain magnetic resonance imaging and electroencephalography were analysed. We searched the Human Gene Mutation Database for the published GABRG2 variants with clinical description of patients and composed a summary of the variants and their phenotypic features.Results: We identified two novel de novo GABRG2 variants, p.P282T and p.S306F, with new phenotypes including neuroradiological evidence of neurodegeneration and epilepsy of infancy with migrating focal seizures (EIMFS). One patient carried previously reported p.P83S variant with autism spectrum disorder (ASD) phenotype that has not yet been described related to GABRG2 disorders and a more severe epilepsy phenotype than reported earlier. In all, the literature search yielded twenty-two articles describing 27 different variants that were divided into two categories: those with self-limiting epilepsies and febrile seizures and those with more severe drug-resistant epileptic encephalopathies.Conclusion: This study further expands the genotypic and phenotypic spectrum of epilepsies associated with GABRG2 variants. More knowledge is still needed about the influence of the environment, genetic background and other epilepsy susceptibility genes on the phenotype of the specific GABRG2 variants. [ABSTRACT FROM AUTHOR]

Background: Current evidence suggests that Gamma-aminobutyric acid (GABA) receptors are associated with the occurrence and progression of cerebrovascular diseases. The present study investigated the association between single nucleotide polymorphisms (SNPs) in the Gamma-aminobutyric acid type A receptor gamma2 subunit ( GABRG2 ) gene and ischemic stroke (IS)., Methods: A total of 120 healthy volunteers and 187 patients with IS were recruited. Patients underwent complete neurological assessment and classification with the National Institute of Health Stroke Scale (NIHSS) and the Trial of ORG 10172 in Acute Stroke Treatment (TOAST). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze SNP sites in 4 different regions ( rs211037 , rs418210 , rs211035 , and rs424740 ) of the GABRG2 gene. SHEsis online platform was used to assess SNP allele and genotype frequencies. Multivariate logistic regression analysis was performed to identify the risk factors for IS., Results: Univariate analysis showed that the T allele and TT genotype distribution for rs211037 were significantly more frequent in the IS group compared to controls ( pallele = 0.01, odds ratio (OR) = 1.673, 95% confidence intervals (CI), 1.119-2.500, pgenotype = 0.03). Furthermore, multivariate logistic regression analysis revealed the TT genotype for rs211037 was an independent risk factor for IS ( p = 0.017, OR = 1.925, 95% CI, 1.122-3.303). Age was also found to be an independent risk factor, and the older the age, the higher the risk of IS ( p = 0.001, OR = 1.047, 95% CI, 1.020-1.073). Finally, subgroup analysis revealed that patients with the rs211037 TT genotype were associated with a higher NIHSS score ( p = 0.03), and that large-artery atherosclerosis (LAA) subtype was predominant in patients with the rs211037 TT genotype ( p = 0.042)., Conclusions: These findings suggest the rs211037 polymorphism in the GABRG2 gene is an independent risk factor for IS in the Chinese population. GABRG2 could thus be a potential biomarker to assess the risk of IS., Competing Interests: The authors declare no conflict of interest., (© 2023 The Author(s). Published by IMR Press.)

GABA has always been an inviting target in the etiology and treatment of epilepsy. The GABRA1, GABRG2, and GABRD genes provide instructions for making α1, ϒ2, and δ subunits of GABAA receptor protein respectively. GABAA is considered as one of the most important proteins and has found to play an important role in many neurological disorders. We explored the association of GABAA receptor gene mutation/SNPs in JME and LGS patients in Indian population. A total of 100 epilepsy syndrome patients (50 JME and 50 LGS) and 100 healthy control subjects were recruited and analyzed by AS-PCR and RFLP-PCR techniques. In our study, GABRA1 965 C > A mutation and 15 A > G polymorphism gene may play an important role in modulating the drug efficacy in LGS patients. The GABRA1 15 A > G polymorphism may also play an important role in the susceptibility of LGS and the inheritance of GG genotype of this polymorphism may provide an increased risk of development of LGS. The GABRG2 588 C > T polymorphism may decrease the duration of seizures in JME patients. The GABRD 659 G > A polymorphism may play an important role in the susceptibility of JME and LGS and this polymorphism may also increase the duration of postictal period in JME patients but may decrease the duration of seizure in LGS patients. [ABSTRACT FROM AUTHOR]

Abstract: Febrile seizure (FS) is the most common type of convulsion in infants and young children. The occurrence of FS in a subset of children with febrile illness suggested genetic factors may have an important effect on the predisposition of the disease. Using targeted next generation sequencing (NGS), a novel splicing variation (NM_198903.2:c.1249-1G>T) was identified in the γ-aminobutyric acid type A (GABA-A) receptor γ2 subunit ( GABRG2 ) gene of a FS patient. To investigate possible association of FS with single nucleotide polymorphisms (SNPs) in prostaglandin-endoperoxide synthase-2 ( prostaglandin G/H synthase-2 ; PTGS2 / cyclooxygenase-2 ; COX2 ) gene involving in thermoregulatory pathway, eight SNPs, rs689465, rs689466, rs20417, rs13306038, rs201931599, rs689470, rs4648306 and rs4648308, along with 2 previously reported variations in IL1RN (86-bp VNTR) and IL10 (rs1900872) were genotyped and utilized for case-control association studies on 35 FS and 31 non-FS controls. A single SNP (rs689466) localized at 5′-1192 of the PTGS2 gene exhibited significant association with FS ( p = 0.045) based on case-control allelic association analyses. A significant decrease in the frequency of the G allele in FS (0.357) was observed compared to that in controls (0.536) with an estimated odds ratio (OR) of 0.48 (95% CI, 0.23–0.99) for the G versus A allele. Using case-control genotypic association analysis, the −1192 A allele is most likely to confer susceptibility to FS by a recessive action model ( p = 0.045, pointwise empirical p value (EMP1) = 0.049). The association of SNPs in PTGS2 , in addition to IL6 , IL-6 receptor ( IL6R ) and prostaglandin E receptor 3 ( PTGER3 ) in prior reports, with FS suggests their possible action in concert to modulate phenotypes in FS as well as the involvement of thermoregulatory pathway in pathogenesis of FS. [ABSTRACT FROM AUTHOR]

Epileptic encephalopathies are a devastating group of severe childhood onset epilepsies with medication-resistant seizures and poor developmental outcomes. Many epileptic encephalopathies have a genetic aetiology and are often associated with de novo mutations in genes mediating synaptic transmission, including GABAA receptor subunit genes. Recently, we performed next generation sequencing on patients with a spectrum of epileptic encephalopathy phenotypes, and we identified five novel (A106T, I107T, P282S, R323W and F343L) and one known (R323Q) de novo GABRG2 pathogenic variants (mutations) in eight patients. To gain insight into the molecular basis for how these mutations contribute to epileptic encephalopathies, we compared the effects of the mutations on the properties of recombinant α1β2γ2L GABAA receptors transiently expressed in HEK293T cells. Using a combination of patch clamp recording, immunoblotting, confocal imaging and structural modelling, we characterized the effects of these GABRG2 mutations on GABAA receptor biogenesis and channel function. Compared with wild-type α1β2γ2L receptors, GABAA receptors containing a mutant γ2 subunit had reduced cell surface expression with altered subunit stoichiometry or decreased GABA-evoked whole-cell current amplitudes, but with different levels of reduction. While a causal role of these mutations cannot be established directly from these results, the functional analysis together with the genetic information suggests that these GABRG2 variants may be major contributors to the epileptic encephalopathy phenotypes. Our study further expands the GABRG2 phenotypic spectrum and supports growing evidence that defects in GABAergic neurotransmission participate in the pathogenesis of genetic epilepsies including epileptic encephalopathies. [ABSTRACT FROM AUTHOR]

Introduction: Pathogenic variants of the GABRG2 gene, encoding a GABAA receptor subunit, have been associated with various epileptic syndromes and drug-resistant epilepsy. Vinpocetine has been previously reported efficacious in a patient harboring a GABRB3 pathogenic variant, encoding another GABAA receptor subunit., Case Presentation: We describe a patient with GABRG2-related drug-resistant epilepsy who improved after vinpocetine treatment. An 8-year-old boy with a family history of epilepsy was diagnosed with early onset absence epilepsy at 6 months of age and was treated unsuccessfully with sodium valproate and ethosuximide. At 6 years of age, he developed generalized tonic-clonic seizures and increasing absences despite lamotrigine add-on as well as learning difficulties. Brain MRI was normal and video-EEG telemetry showed multiple myoclonic absences. An epilepsy gene panel analysis showed a GABRG2 pathogenic variant, c.254 T > A p.(Ile85Lys) (NM_198903.2), inherited from the proband's father. Seizures were resistant to several medications. After treatment with vinpocetine add-on, the patient showed a dramatic initial response, further reduction of seizures, and improvement of his cognitive functions., Conclusion: This case illustrates that vinpocetine could be considered in drug-resistant epilepsies related to GABRG2 in accordance with the principles of precision medicine., (© 2023 International League Against Epilepsy.)

The purpose of the study was to explore the pathogenic mechanisms underlying generalized epilepsy and febrile seizures plus (GEFS+) in a family with a novel γ2 subunit gene (GABRG2) frameshift mutation. Four affected and one unaffected individuals carried a c.1329delC GABRG2 mutation resulting in a subunit [γ2S(S443delC)] with a modified and elongated carboxy-terminus that is different from that of the wildtype γ2S subunit. We expressed the wildtype γ2S subunit and the predicted mutant γ2S(S443delC) subunit cDNAs in HEK293T cells and performed immunoblotting, flow cytometry and electrophysiology studies. The mutant subunit was translated as a stable protein that was larger than the wildtype γ2S subunit and was retained in the ER and not expressed on the cell surface membrane, suggesting GABRG2 haploinsufficiency. Peak GABA-evoked currents recorded from cells cotransfected with wildtype α1 and β2 subunits and mutant γ2S subunits were significantly decreased and were comparable to α1β2 receptor currents. S443delC is the first GABR epilepsy mutation predicted to abolish the natural stop codon and produce a stop codon in the 3′ UTR that leads to translation of an extended peptide. The GEFS+ phenotype observed in this family is likely caused by γ2S subunit loss-of-function and possibly to dominant-negative suppression of α1β2γ2 receptors. Many GABRG2 truncation mutations result in GEFS+, but the spectrum of phenotypic severity is wider, ranging from asymptomatic individuals to the Dravet syndrome. Mechanisms influencing the severity of the phenotype are therefore complex and difficult to correlate with its demonstrable functional effects.

Gamma-aminobutyric acid receptor (GABA-A) is the most common receptor of fast synaptic inhibition in the human brain. Gamma protein encoded by the GABRG2 gene is one of the subunits of the GABA-A receptor, which plays an essential role in the function of this receptor. Several studies have identified various febrile seizure (FS) and epilepsy risk variants of GABRG2 gene in different populations, but some others did not support these results. The aim of this case-control study is to investigate whether GABRG2 polymorphisms contribute to susceptibility for FS and epilepsy in pooled data of three cohorts, from Malaysia (composed of Malay, Chinese, and Indian), Hong Kong, and Korea. Furthermore, the pooled dataset of these cohorts with previous reports were meta-analyzed for determining the risk effect size of the rs211037 polymorphism on FS and symptomatic epilepsy (SE). The rs211037, rs210987, rs440218, rs2422106, rs211014, and rs401750 polymorphisms were genotyped in the 6442 subjects (1729 epilepsy and 4713 controls). Results of the case-control study showed associations between rs211037 and the risk of SE in the pooled data from all cohorts (T vs. C, p = 3 × 10, and TT vs. CC, p = 2 × 10) and the risk of partial seizure in the combined data of Malaysia and Hong Kong (both T vs. C and TT vs. CC, p = 2 × 10). The rs211037-rs210987 and rs2422106-rs211014-rs401750 haplotypes were also associated with susceptibility to SE in Chinese. Meta-analysis of all Asians identified association between rs211037 and FS and SE (T vs. C, p = 4 × 10, and p = 4 × 10, respectively). In conclusion, rs211037 alone may be a risk factor for FS, partial seizure, and SE, and in linkage disequilibrium with rs210987 can contribute to FS and SE in Asians, particularly in Chinese. [ABSTRACT FROM AUTHOR]