The possible effect of SCN1A and SCN2A genetic variants on carbamazepine response among Khyber Pakhtunkhwa epileptic patients, Pakistan

Genetic Analysis of Sodium Channel Genes in Pediatric Epilepsy Patients of Pakistan

Epilepsy affects millions of people worldwide. Although antiepileptic drugs work for the majority of epileptic patients, these drugs do not work for some of the patients, subjecting them to drug-resistant epilepsy (DRE). Voltage-gated sodium channels act as targets for a number of antiepileptic drugs, and the genes encoding these channels can play a crucial role in developing drug-resistant epilepsy. This case-control (100 control: 101patients) study evaluated the association of sodium channel genes SCN1A and SCN2A with drug-resistant epilepsy. The cases were further accounted in two categories, drug-resistant and drug-responsive epileptic patients. The polymorphic sites rs794726754, rs1057518252, rs121918809, rs12191792, rs121917932, c.730 G > T, c.735 G > T, c.736 A > T, rs10167228, and rs2298771 of the SCN1A gene and rs17183814 of SCN2A gene were selected for mutational analysis. The DNA was isolated, amplified by PCR, and then, was run through 1% agarose gel. The sequencing was performed, and the sequences were observed through BioEdit software for any change in DNA sequence. In our study, no polymorphism was observed in the studied SNPs except for rs2298771. For rs2298771, a significant difference existed in the distribution of genotypic and allelic frequencies (p < 0.01) among the case and control group. Furthermore, the genotypic and allelic frequencies of the two categories of cases (drug responder drug resistant) were calculated. The genotypic and allelic frequencies of drug-responsive and drug-resistant epileptic patients did not differ significantly (p > 0.01). Our study indicated that the rs2298771 polymorphism of SCN1A may not be associated with chance of developing DRE in the Pakistani population.

ABCB1 c.3435C > T and EPHX1 c.416A > G polymorphisms influence plasma carbamazepine concentration, metabolism, and pharmacoresistance in epileptic patients

The gene polymorphisms of ABCB1, EPHX1, and SCN1A were found to influence carbamazepine (CBZ) metabolism and resistance in epilepsy patients, but the relevance remains controversial. To reveal the relationships among the gene polymorphisms of ABCB1, EPHX1, SCN1A and the metabolism and resistance of CBZ, the databases of PubMed, EMBASE, Cochrane Library, Chinese National Knowledge Infrastructure, Chinese Science and Technique Journals, China Biology medicine disc and Wan Fang were retrieved for suitable studies up to April 2021. 18 studies containing 3293 epilepsy patients were included. The result revealed the gene polymorphism of ABCB1 c.3435C > T is significantly associated with altered concentration-dose ratios of CBZ (CDR_CBZ) (CC vs. CT, OR = 0.25 (95% CI: 0.08-0.42), P = 0.004), and EPHX c.416A > G gene polymorphism may also significantly adjusted the concentration-dose ratios of carbamazepine-10, 11-trans dihydrodiol (CDR_CBZD) (AA vs. GG, OR = 0.48 (95% CI: 0.01-0.96), P = 0.045; AG vs. GG, OR = 0.68 (95% CI: 0.16-1.20), P = 0.010, respectively) and the ratio of CBZD:carbamazepine-10,11-epoxide (CBZE) (CDR_CBZD:CDR_CBZE) (AG vs GG, OR = 0.83 (95% CI: 0.31-1.36), P = 0.002). Furthermore, ABCB1 c.3435C > T polymorphism was also observed to be significantly influenced CBZ resistance (CC vs TT, OR = 1.78 (95% CI: 1.17-2.72), P = 0.008; CT vs TT, OR = 1.60 (95% CI: 1.12-2.30), P = 0.01; CC + CT vs TT, OR = 1.61 (95% CI: 1.15-2.26), P = 0.006, respectively). Therefore, CBZ metabolism and resistance in patients with epilepsy may be adjusted by the gene polymorphisms of ABCB1 c.3435C > T and EPHX1 c.416A > G which provides the further scientific basis for clinical individualized therapy of epilepsy. However, larger sample size studies are still needed to provide further conclusive evidence.

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

BACKGROUND

Carbamazepine (CBZ) is one of most used antiepileptic drugs. However, CBZ-resistance is common in patients with epilepsy, and genetic polymorphisms can influence antiepileptic drug responsiveness. The association between the polymorphisms rs3812718 and rs2298771 of theSCN1A gene and risk of resistance to CBZ in epilepsy remains controversial. To further assess the pooled association, we conducted an updated meta-analysis to investigate the contribution of the two SCN1A single nucleotide polymorphisms that may confer CBZ-resistance.

METHODS

We searched PubMed, Embase, and Web of Science databases for eligible studies. All the case-controlled studies related to the association of the SCN1A polymorphisms, rs3812718 and rs2298771, with CBZ-resistance in epilepsy were included. Pooled odds ratios (OR) as well as the corresponding 95 % confidence intervals (CI) were determined.

RESULTS

A total of eight out of 255 articles were used to assess the association between SCN1A and CBZ-resistance in epilepsy. We found a significant association between rs2298771 (GG vs GA + AA; OR 3.19, 95 % CI 1.27 - 8.02, p > 0.05, I² = 0) and CBZ-resistance in epilepsy patients of Asian ethnicity. No association was observed between the rs3812718 polymorphism and CBZ responsiveness.

CONCLUSION

Our results indicate that Asian patients with epilepsy and the SCN1A rs2298771 polymorphism, especially the GG genotype, may be at risk of CBZ-resistance.

Associations between CYP3A4, CYP3A5 and SCN1A polymorphisms and carbamazepine metabolism in epilepsy: A meta-analysis

BACKGROUND AND OBJECTIVE

CYP3A4 (rs2242480), CYP3A5 (rs776746) and SCN1A (rs3812718 and rs2298771) gene polymorphisms were previously indicated to be associated with carbamazepine (CBZ) metabolism and resistance in epilepsy. However, previous studies regarding the effects of these polymorphisms still remain controversial. Therefore, we performed a meta-analysis to evaluate whether the four polymorphisms are associated with CBZ metabolism and resistance.

METHODS

The PubMed, EMBASE, Cochrane library, Chinese National Knowledge Infrastructure, Chinese Science and Technique Journals Database, China Biology Medicine disc and Wan Fang Database were searched up to January 2021 for appropriate studies regarding the association of rs2242480, rs776746, rs3812718 and rs2234922 polymorphisms with CBZ metabolism and resistance. The meta-analysis was conducted by Review Manager 5.3 software.

RESULTS

Eighteen studies involving 2546 related epilepsy patients were included. We found that the G allele of CYP3A4 rs2242480 markedly decreased the plasma CBZ concentration in epilepsy. For CYP3A5 rs776746 polymorphism, the GG genotype (homozygote codominant model: GG vs. AA) and GG + GA genotype (dominant model: GG + GA vs. AA and recessive model: GG vs. GA + AA) were respectively found to be significantly associated with increased CBZ plasma concentration. Additionally, it was also found that the SCN1A rs3812718 A allele was significantly associated with decreased CBZ plasma concentration and increased CBZ resistance. However, no association was observed between SCN1A rs2298771 polymorphism and CBZ metabolism and resistance.

CONCLUSION

The CYP3A4 rs2242480, CYP3A5 rs776746 and SCN1A rs3812718 polymorphisms may play important roles in CBZ metabolism and resistance, while SCN1A rs2298771 polymorphism is not associated with CBZ in epilepsy. These findings would improve the individualized therapy of epileptic patients in clinics.

Association Between SCN1A rs2298771, SCN1A rs10188577, SCN2A rs17183814, and SCN2A rs2304016 Polymorphisms and Responsiveness to Antiepileptic Drugs: A Meta-Analysis

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.

Neonatal Tactile Stimulations Affect Genetic Generalized Epilepsy and Comorbid Depression-Like Behaviors

Recent studies suggest that development of absence epilepsy and comorbid depression might be prevented by increased maternal care of the offspring, in which tactile stimulation induced by licking/grooming and non-nutritive contact seem to be crucial. In this study, we aimed to evaluate the effect of neonatal tactile stimulations (NTS) on absence epilepsy and depression-like behaviors in adulthood. Wistar Albino Glaxo from Rijswijk (WAG/Rij) rat pups with a genetic predisposition to absence epilepsy were divided into tactile stimulation (TS) group, deep touch pressure (DTP) group, maternal separation (MS) group or control group. Between postnatal day 3 and 21, manipulations (TS, DTP, and MS) were carried out for 15 min and three times a day. Animals were submitted to locomotor activity, sucrose consumption test (SCT) and forced swimming test (FST) at five months of age. At the age of six months, the electroencephalogram (EEG) recordings were conducted in order to quantify the spike-wave discharges (SWDs), which is the hallmark of absence epilepsy. The TS and DTP groups showed less and shorter SWDs in later life in comparison to maternally separated and control rats. SWDs’ number and total duration were significantly reduced in TS and DTP groups whereas mean duration of SWDs was reduced only in DTP group (p < 0.05). TS and DTP also decreased depression-like behaviors measured by SCT and FST in adult animals. In the SCT, number of approaches was significantly higher in TS and DTP groups than the maternally separated and control rats. In the FST, while the immobility latency of TS and DTP groups was significantly higher, only TS group showed significantly decreased immobility and increased swimming time. The results showed that NTS decreases both the number and length of SWDs and the depression-like behaviors in WAG/Rij rats probably by increasing arousal level and causing alterations in the level of some neurotrophic factors as well as in functions of the neural plasticity in the developing rat’s brain.