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SCN1A splice variants exhibit divergent sensitivity to commonly used antiepileptic drugs.

ABSTRACT: A common genetic variant (rs3812718) in a splice donor consensus sequence within the neuronal sodium channel gene SCN1A (encoding Na(V) 1.1) modulates the proportion of transcripts incorporating either the canonical (5A) or alternative (5N) exon 5. A pharmacogenetic association has been reported whereby increased expression of exon 5N containing Na(V) 1.1 transcripts correlated with lower required doses of phenytoin in epileptics. We tested the hypothesis that SCN1A alternative splicing affects the pharmacology of Na(V) 1.1 channels.To directly examine biophysical and pharmacologic differences between the exon 5 splice variants, we performed whole-cell patch clamp recording of tsA201 cells transiently coexpressing either Na(V) 1.1-5A or Na(V) 1.1-5N with the ?1 and ?2 accessory subunits. We examined tonic inhibition and use-dependent inhibition of Na(V) 1.1 splice isoforms by phenytoin, carbamazepine, and lamotrigine. We also examined the effects of phenytoin and lamotrigine on channel biophysical properties and determined concentration-response relationships for both splice variants.We observed no significant differences in voltage dependence of activation, steady-state inactivation, and recovery from inactivation between splice variants. However, Na(V) 1.1-5N channels exhibited enhanced tonic block by phenytoin and lamotrigine compared to Na(V) 1.1-5A. In addition, Na(V) 1.1-5N exhibited enhanced use-dependent block by phenytoin and lamotrigine across a range of stimulation frequencies and concentrations. Phenytoin and lamotrigine induced shifts in steady-state inactivation and recovery from fast inactivation for both splice isoforms. No splice isoform differences were observed for channel inhibition by carbamazepine.These results suggest Na(V) 1.1 channels containing exon 5N are more sensitive to the commonly used antiepileptic drugs phenytoin and lamotrigine.

SUBMITTER: Thompson CH

PROVIDER: S-EPMC3093448 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

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SCN1A splice variants exhibit divergent sensitivity to commonly used antiepileptic drugs.

Thompson Christopher H CH Kahlig Kristopher M KM George Alfred L AL

Epilepsia 20110331 5

<h4>Purpose</h4>A common genetic variant (rs3812718) in a splice donor consensus sequence within the neuronal sodium channel gene SCN1A (encoding Na(V) 1.1) modulates the proportion of transcripts incorporating either the canonical (5A) or alternative (5N) exon 5. A pharmacogenetic association has been reported whereby increased expression of exon 5N containing Na(V) 1.1 transcripts correlated with lower required doses of phenytoin in epileptics. We tested the hypothesis that SCN1A alternative s ...[more]

PMID: 21453355

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Project description:BackgroundThis active, open observational study aimed to investigate adverse drug reactions (ADRs) associated with six commonly used antiepileptic drugs (AEDs) in southern Chinese outpatients with epilepsy from 2003 to 2015.MethodsThe Wenzhou Epilepsy Follow-Up Registry Database (WEFURD) was established by a single epilepsy center in China in January 2003 to record AED efficacy and the associated ADRs by registered outpatients diagnosed with epilepsy. We reviewed the data of outpatients who had only taken one or more of six commonly used AEDs, namely, carbamazepine (CBZ), valproate (VPA), lamotrigine (LTG), oxcarbazepine (OXC), topiramate (TPM) and levetiracetam (LEV), and were registered in the WEFURD between 2003 and 2015. We evaluated the ADRs caused by the single or combined use of the above six specific AEDs based on the WHO-UMC scale. The data of the ADRs were categorized by age, sex, number of AEDs related to ADRs, medications, seriousness of ADRs, causality levels of the WHO-UMC scale and system organ class (SOC). The unit of analysis was one ADR.ResultsA total of 3069 epilepsy outpatients (1807 outpatients with 5049 eligible ADRs and 1262 outpatients without ADRs) were included. The overall ADR rate was 58.88% (1807/3069). An average of 2.79 ADRs (5049/1807) occurred per patient with an ADR; 53.8% of the 5049 ADRs were recorded in females, and 50.4% were caused by monotherapy. Of the ADRs, 10.6% (537/5049) were severe adverse reactions (SARs), including 34 serious adverse effects (SAEs). The SAR rates caused by one, two and three or more AEDs were 9.9, 10.0 and 19.6%, respectively (p < 0.001). Eighteen SOC categories were identified, and the top three were psychiatric disorders (1633/5049, 32.3%), neurological disorders (1222/5049, 24.2%) and gastrointestinal disorders (564/5049, 11.2%). Of the 537 SARs, skin and appendage disorders accounted for 24.4% (131/537). Among the 34 SAEs, serious allergies, fetal malformations, renal calculus and pancreatitis accounted for the majority.ConclusionsOur findings suggest that clinicians should pay attention to psychiatric ADRs and be alert for SARs, especially when three or more AEDs are used together. Moreover, active surveillance might provide another method of pharmacovigilance in China.

Project description:OBJECTIVES:To assess the association between prenatal exposure to monotherapy with the antiepileptic drugs (AEDs) most commonly used during pregnancy and the risk of various neurodevelopmental outcomes compared with lamotrigine. DESIGN:Nationwide population-based cohort study. SETTING:French national healthcare databases. PARTICIPANTS:Children born alive between 2011 and 2014 and prenatally exposed to AED monotherapy. PRIMARY AND SECONDARY OUTCOME MEASURES:Outcomes included neurodevelopmental disorders (NDD), defined by International Classification of Diseases, 10th Revision codes F70-F98-pervasive developmental disorders (PDD, F84) and mental retardation (MR, F70-F79) were studied separately-and visits to speech therapists. The reference group comprised children prenatally exposed to lamotrigine. Children were followed until outcome, loss to follow-up, death or 31 December 2016. We performed inverse probability of treatment weighting analyses using the propensity score, which included maternal and infant characteristics. Hazard ratios (HRs) were calculated using Cox models. RESULTS:The cohort comprised 9034 children, 2916 of which were exposed to lamotrigine, 1627 to pregabalin, 1246 to clonazepam, 991 to valproic acid (VPA), 621 to levetiracetam, 502 to carbamazepine, 477 to topiramate, 378 to gabapentin and 143 to oxcarbazepine. None of these AEDs, except VPA, was associated with an increased risk of any of the four neurodevelopmental outcomes investigated. Exposure to VPA was associated with increased risks of NDDs (HR=2.7, 95% CI (1.8 to 4.0)), PDD (HR=4.4 (2.1 to 9.3)), MR (HR=3.1 (1.5 to 6.2)) and visits to speech therapists (HR=1.5 (1.1 to 1.9)), with a dose-response relationship. CONCLUSIONS:No increased risk of any of the neurodevelopmental outcomes investigated in this study was observed with prenatal exposure to levetiracetam, pregabalin, oxcarbazepine, topiramate, gabapentin, clonazepam or carbamazepine, compared with lamotrigine. However, this study corroborates the well-known association between maternal use of VPA during pregnancy and the risk of neurodevelopmental disorders in the offspring. Longer follow-up is necessary to confirm these findings.

Project description:Background: Genetic interindividual variability is associated with adverse drug reactions (ADRs) and affects the response to common drugs used in anesthesia. Despite their importance, these variants remain largely underexplored in Latin-American countries. This study describes rare and common variants found in genes related to metabolism of analgesic and anaesthetic drug in the Colombian population. Methods: We conducted a study that included 625 Colombian healthy individuals. We generated a subset of 14 genes implicated in metabolic pathways of common medications used in anesthesia and assessed them by whole-exome sequencing (WES). Variants were filtered using two pipelines: A) novel or rare (minor allele frequency-MAF <1%) variants including missense, loss-of-function (LoF, e.g., frameshift, nonsense), and splice site variants with potential deleterious effect and B) clinically validated variants described in the PharmGKB (categories 1, 2 and 3) and/or ClinVar databases. For rare and novel missense variants, we applied an optimized prediction framework (OPF) to assess the functional impact of pharmacogenetic variants. Allelic, genotypic frequencies and Hardy-Weinberg equilibrium were calculated. We compare our allelic frequencies with these from populations described in the gnomAD database. Results: Our study identified 148 molecular variants potentially related to variability in the therapeutic response to 14 drugs commonly used in anesthesiology. 83.1% of them correspond to rare and novel missense variants classified as pathogenic according to the pharmacogenetic optimized prediction framework, 5.4% were loss-of-function (LoF), 2.7% led to potential splicing alterations and 8.8% were assigned as actionable or informative pharmacogenetic variants. Novel variants were confirmed by Sanger sequencing. Allelic frequency comparison showed that the Colombian population has a unique pharmacogenomic profile for anesthesia drugs with some allele frequencies different from other populations. Conclusion: Our results demonstrated high allelic heterogeneity among the analyzed sampled, enriched by rare (91.2%) variants in pharmacogenes related to common drugs used in anesthesia. The clinical implications of these results highlight the importance of implementation of next-generation sequencing data into pharmacogenomic approaches and personalized medicine.

Project description:Background: SCN1A and SCN2A genes have been reported to be associated with the efficacy of single and combined antiepileptic therapy, but the results remain contradictory. Previous meta-analyses on this topic mainly focused on the SCN1A rs3812718 polymorphism. However, meta-analyses focused on SCN1A rs2298771, SCN1A rs10188577, SCN2A rs17183814, or SCN2A rs2304016 polymorphisms are scarce or non-existent. Objective: We aimed to conduct a meta-analysis to determine the effects of SCN1A rs2298771, SCN1A rs10188577, SCN2A rs17183814, and SCN2A rs2304016 polymorphisms on resistance to antiepileptic drugs (AEDs). Methods: We searched the PubMed, Embase, Cochrane Library, WANFANG, and CNKI databases up to June 2020 to collect studies on the association of SCN1A and SCN2A polymorphisms with reactivity to AEDs. We calculated the pooled odds ratios (ORs) under the allelic, homozygous, heterozygous, dominant, and recessive genetic models to identify the association between the four single-nucleotide polymorphisms (SNPs) and resistance to AEDs. Results: Our meta-analysis included 19 eligible studies. The results showed that the SCN1A rs2298771 polymorphism was related to AED resistance in the allelic, homozygous, and recessive genetic models (G vs. A: OR = 1.20, 95% CI: 1.012-1.424; GG vs. AA: OR = 1.567, 95% CI: 1.147-2.142; GG vs. AA + AG: OR = 1.408, 95% CI: 1.053-1.882). The homozygous model remained significant after Bonferroni correction (P < 0.0125). Further subgroup analyses demonstrated the significance of the correlation in the dominant model in Caucasians (South Asians) after Bonferroni correction (GG + GA vs. AA: OR = 1.620, 95% CI: 1.165-2.252). However, no association between SCN1A rs2298771 polymorphism and resistance to AEDs was found in Asians or Caucasians (non-South Asians). For SCN1A rs10188577, SCN2A rs17183814, and SCN2A rs2304016 polymorphisms, the correlations with responsiveness to AEDs were not significant in the overall population nor in any subgroup after conducting the Bonferroni correction. The results for SCN1A rs2298771, SCN1A rs10188577, and SCN2A rs2304016 polymorphisms were stable and reliable according to sensitivity analysis and Begg and Egger tests. However, the results for SCN2A rs17183814 polymorphism have to be treated cautiously owing to the significant publication bias revealed by Begg and Egger tests. Conclusions: The present meta-analysis indicated that SCN1A rs2298771 polymorphism significantly affects resistance to AEDs in the overall population and Caucasians (South Asians). There were no significant correlations between SCN1A rs10188577, SCN2A rs17183814, and SCN2A rs2304016 polymorphisms and resistance to AEDs.

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SCN1A splice variants exhibit divergent sensitivity to commonly used antiepileptic drugs.

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SCN1A splice variants exhibit divergent sensitivity to commonly used antiepileptic drugs.

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