Association between SCN1A polymorphism and carbamazepine responsiveness in epilepsy: A meta-analysis

Exploring the mechanism of carbamazepine decreasing testosterone levels based on cAMP/PKA/CREB pathway

The aim of this study was to explore the molecular mechanisms underlying carbamazepine (CBZ)-induced testicular toxicity and testosterone reduction in rats. For this purpose, Sprague-Dawley (SD) rats were intervened with 200 mg/kg CBZ for 12 weeks, and R2C cells were exposed to CBZ at concentrations of 0.5, 1 and 1.5 mM for 24 h. HE, Tunel, ELISA, immunofluorescence staining, RT-qPCR, and western blot were used to reveal the effects of CBZ on spermatozoa quality, testicular tissue structure, testosterone level and testosterone synthesis-related enzymes in rats. The results showed that CBZ significantly damaged the testicular tissue structure of rats, induced cell apoptosis, down-regulated the gene and protein expression levels of testosterone synthesis-related enzymes (STAR, TSPO, 17β-HSD and 3β-HSD), inhibited the expression of related proteins in the cAMP/PKA/CREB signalling pathway, and suppressed testosterone levels. In addition, the use of Db-cAMP (a PKA activator) significantly upregulated the protein expressions of PKA and p-CREB, evidently alleviated the CBZ-induced decrease in testosterone levels. In conclusion, CBZ induced testosterone resynthesis by inhibiting the cAMP/PKA/CREB pathway, affecting the expression of steroid synthesis-related enzymes and reducing testosterone levels.

Single-Base Gene Variants in MIR-146A and SCN1A Genes Related to the Epileptogenic Process in Drug-Responsive and Drug-Resistant Temporal Lobe Epilepsy-A Preliminary Study in a Brazilian Cohort Sample

The drug-resistant temporal lobe epilepsy (TLE) has recently been associated with single nucleotide variants (SNVs) in microRNA(miR)-146a (MIR-146A) (rs2910164) and Sodium Voltage-Gated Channel Alpha Subunit 1 (SCN1A) (rs2298771 and rs3812718) genes. Moreover, no studies have shown an association between these SNVs and susceptibility to drug-resistant and drug-responsive TLE in Brazil. Thus, deoxyribonucleic acid (DNA) samples from 120 patients with TLE (55 drug-responsive and 65 drug-resistant) were evaluated by real-time polymerase chain reaction (RT-PCR). A total of 1171 healthy blood donor individuals from the Online Archive of Brazilian Mutations (ABraOM, from Portuguese Arquivo Brasileiro On-line de Mutações), a repository containing genomic variants of the Brazilian population, were added as a control population for the studied SNVs. MIR-146A and SCN1A relative expression was performed by quantitative RT-PCR (qRT-PCR). The statistical analysis protocol was performed using an alpha error of 0.05. TLE patient samples and ABraOM control samples were in Hardy-Weinberg equilibrium for all studied SNVs. For rs2910164, the frequencies of the homozygous genotype (CC) (15.00% vs. 9.65%) and C allele (37.80% vs. 29.97%) were superior in patients with TLE compared to controls with a higher risk for TLE disease [odds ratio (OR) = 1.89 (95% confidence interval (95%CI) = 1.06-3.37); OR = 1.38 (95%CI = 1.04-1.82), respectively]. Drug-responsive patients also presented higher frequencies of the CC genotype [21.81% vs. 9.65%; OR = 2.58 (95%CI = 1.25-5.30)] and C allele [39.09% vs. 29.97%; OR = 1.50 (95%CI = 1.01-2.22)] compared to controls. For rs2298771, the frequency of the heterozygous genotype (AG) (51.67% vs. 40.40%) was superior in patients with TLE compared to controls with a higher risk for TLE disease [OR = 2.42 (95%CI = 1.08-5.41)]. Drug-resistant patients presented a higher AG frequency [56.92% vs. 40.40%; OR = 3.36 (95%CI = 1.04-17.30)] compared to the control group. For rs3812718, the prevalence of genotypes and alleles were similar in both studied groups. The MIR-146A relative expression level was lower in drug-resistant compared to drug-responsive patients for GC (1.6 vs. 0.1, p-value = 0.049) and CC (1.8 vs. 0.6, p-value = 0.039). Also, the SCN1A relative expression levels in samples from TLE patients were significantly higher in AG [2.09 vs. 1.10, p-value = 0.038] and GG (3.19 vs. 1.10, p-value < 0.001) compared to the AA genotype. In conclusion, the rs2910164-CC and rs2298771-AG genotypes are exerting significant risk influence, respectively, on responsive disease and resistant disease, probably due to an upregulated nuclear factor kappa B (NF-kB) and SCN1A loss of function.

Association between the SLC6A11 rs2304725 and GABRG2 rs211037 polymorphisms and drug-resistant epilepsy: a meta-analysis

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 I ² statistic were selected. According to study heterogeneity, we chose fixed- or 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.

Polymorphisms of the sodium voltage-gated channel, alpha subunit 1 (SCN1A -A3184G) gene among children with non-lesional epilepsy: a case-control study

BACKGROUND

Mutations in the neuronal sodium voltage-gated channel, alpha subunit 1 (SCN1A) gene have been associated with epilepsy. We investigated the SCN1A-A3184G polymorphism among Egyptian children and adolescents with non-lesional epilepsy.

METHODS

A prospective case - control observational study was done in Mansoura University Children's Hospital, Egypt including 326 children with non-lesional epilepsy (163 antiepileptic drugs (AEDs) resistant cases & 163 AEDs responders) and 163 healthy controls. One step real time polymerase chain reaction (PCR) was used for the molecular analysis. Student's t-test, and Monto Carlo, chi-square and Mann-Whitney tests were used for the statistical analysis.

RESULTS

All study participants were matched as regards the age, sex and body weight (p = 0.07, 0.347 and 0.462, respectively). They had the (AA) and (AG) genotypes but not the (GG) variant. No significant differences were found between cases and controls regarding (AG) and (AA) genotypes and A- and G-alleles (p = 0.09 and 0.3, respectively). We did not find significant differences between AEDs responders and resistant cases regarding the studied genotypes and alleles (p = 0.61 and 0.746, respectively). In the resistant group, we observed significant associations between the (AG) genotype and seizure frequency (p = 0.05), the tonic-clonic seizure (p < 0.001), the younger age of first seizure attack (p = 0.03), abnormal electroencephalogram (EEG) (p < 0.001), the positive family history of epilepsy (p = 0.006), topiramate (p = 0.03) and valproic acid (p < 0.001), while the (AA) genotype was associated with carbamazepine (p = 0.03). While in AEDs responders, there were significant associations between the AG genotype and the abnormal EEG activity, levetiracetam and carbamazepine (p = 0.016, 0.028 and 0.02).

CONCLUSIONS

The SCN1A-A3184G genotypes and alleles were not associated with the epilepsy risk among Egyptian children. Significant associations were reported between the AG genotype and some predictors of refractory epilepsy.

Pharmacogenetics of Drug-Resistant Epilepsy (Review of Literature)

Pharmacogenomic studies in epilepsy are justified by the high prevalence rate of this disease and the high cost of its treatment, frequent drug resistance, different response to the drug, the possibility of using reliable methods to assess the control of seizures and side effects of antiepileptic drugs. Candidate genes encode proteins involved in pharmacokinetic processes (drug transporters, metabolizing enzymes), pharmacodynamic processes (receptors, ion channels, enzymes, regulatory proteins, secondary messengers) and drug hypersensitivity (immune factors). This article provides an overview of the literature on the influence of genetic factors on treatment in epilepsy.

Relevance of NR1I2 variants on carbamazepine therapy in Mexican Mestizos with epilepsy at a tertiary-care hospital

Aim: We evaluated the potential influence of genetic (CYP3A5, EPHX1, NR1I2, HNF4A, ABCC2, RALBP1, SCN1A, SCN2A and GABRA1) and nongenetic factors on carbamazepine (CBZ) response, adverse drug reactions and CBZ plasma concentrations in 126 Mexican Mestizos (MM) with epilepsy. Subjects & methods: Patients were genotyped for 27 variants using TaqMan^® assays. Results: CBZ response was associated with NR1I2 variants and lamotrigine cotreatment. CBZ-induced adverse drug reactions were related to antiepileptic polytherapy and SCN1A rs2298771/rs3812718 haplotype. CBZ plasma concentrations were influenced by NR1I2-rs2276707 and -rs3814058, and by phenytoin cotreatment. CBZ daily dose was also influenced by NR1I2-rs3814055 and EPHX1-rs1051740. Conclusion: Interindividual variability in CBZ treatment was partly explained by NR1I2, EPHX1 and SCN1A variants, as well as antiepileptic cotreatment in MM with epilepsy.