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De-novo mutations and genetic variation in the SCN1A gene in Malaysian patients with generalized epilepsy with febrile seizures plus (GEFS+)

Tan EH, Razak SA, Abdullah JM, Mohamed Yusoff AA

Epilepsy Res, 2012 Dec;102(3):210-5.
PMID: 22944210 DOI: 10.1016/j.eplepsyres.2012.08.004

Generalized epilepsy with febrile seizures plus (GEFS+) comprises a group of clinically and genetically heterogeneous epilepsy syndrome. Here, we provide the first report of clinical presentation and mutational analysis of SCN1A gene in 36 Malaysian GEFS+ patients. Mutational analysis of SCN1A gene revealed twenty seven sequence variants (missense mutation and silent polymorphism also intronic polymorphism), as well as 2 novel de-novo mutations were found in our patients at coding regions, c.5197A>G (N1733D) and c.4748A>G (H1583R). Our findings provide potential genetic insights into the pathogenesis of GEFS+ in Malaysian populations concerning the SCN1A gene mutations.

Matched MeSH terms: NAV1.1 Voltage-Gated Sodium Channel/genetics*
Whole exome sequencing identifies a novel SCN1A mutation in genetic (idiopathic) generalized epilepsy and juvenile myoclonic epilepsy subtypes

Chan CK, Low JS, Lim KS, Low SK, Tan CT, Ng CC

Neurol Sci, 2020 Mar;41(3):591-598.
PMID: 31720899 DOI: 10.1007/s10072-019-04122-9

INTRODUCTION: Genetic (idiopathic) generalized epilepsy (GGE) is a common form of epilepsy characterized by unknown aetiology and a presence of genetic component in its predisposition.
METHODS: To understand the genetic factor in a family with GGE, we performed whole exome sequencing (WES) on a trio of a juvenile myoclonic epilepsy/febrile seizure (JME/FS) proband with JME/FS mother and healthy father. Sanger sequencing was carried out for validation of WES results and variant detection in other family members.
RESULTS: Predictably damaging variant found in affected proband and mother but absent in healthy father in SCN1A gene was found to be associated with generalized epilepsy and febrile seizure. The novel non-synonymous substitution (c.5753C>T, p.S1918F) in SCN1A was found in all family members with GGE, of which 4/8 were JME subtypes, and/or febrile seizure, while 3 healthy family member controls did not have the mutation. This mutation was also absent in 41 GGE patients and 414 healthy Malaysian Chinese controls.
CONCLUSION: The mutation is likely to affect interaction between the sodium channel and calmodulin and subsequently interrupt calmodulin-dependent modulation of the channel.

Matched MeSH terms: NAV1.1 Voltage-Gated Sodium Channel/genetics*
RORA gene rs12912233 and rs880626 polymorphisms and their interaction with SCN1A rs3812718 in the risk of epilepsy: a case-control study in Malaysia

Haerian BS, Sha'ari HM, Tan HJ, Fong CY, Wong SW, Ong LC, et al.

Genomics, 2015 Apr;105(4):229-36.
PMID: 25668517 DOI: 10.1016/j.ygeno.2015.02.001

RAR-related orphan receptors A (RORA) and B (RORB) and voltage-gated sodium channel type 1 (SCN1A) genes play critical roles in the regulation of the circadian clock. Evidence has shown an association of RORA and RORB polymorphisms with susceptibility to autism and depression. Hence, we tested the association of RORA rs12912233, rs16943429, rs880626, rs2290430, and rs12900948; RORB rs1157358, rs7022435, rs3750420, and rs3903529; and SCN1A rs3812718 with epilepsy risk in the Malaysians. DNA was genotyped in 1789 subjects (39% epilepsy patients) by using MassARRAY (Sequenom). Significant association was obtained for rs12912233 in Malaysian Chinese (p=0.003). Interaction between rs12912233-rs880626 and rs3812718 was associated with the epilepsy risk in the subjects overall (p=0.001). Results show that RORA rs12912233 alone might be a possible risk variant for epilepsy in Malaysian Chinese, but that, together with RORA rs880626 and SCN1A rs3812718, this polymorphism may have a synergistic effect in the epilepsy risk in Malaysians.

Matched MeSH terms: NAV1.1 Voltage-Gated Sodium Channel/genetics*
SCN1A IVS5N+5 polymorphism and response to sodium valproate: a multicenter study

Haerian BS, Baum L, Tan HJ, Kwan P, Raymond AA, Saruwatari J, et al.

Pharmacogenomics, 2012 Oct;13(13):1477-85.
PMID: 23057548 DOI: 10.2217/pgs.12.127

Approximately 30% of epilepsy patients do not response to antiepileptic drugs (AEDs). The functional SCN1A IVS5N+5 polymorphism may play a role in response to some AEDs. The purpose of this study was to examine this hypothesis in a cohort study of Malaysian and Hong Kong Chinese epilepsy patients on sodium valproate (VPA) monotherapy and in a meta-analysis.

Matched MeSH terms: NAV1.1 Voltage-Gated Sodium Channel/genetics*
SCN1A, SCN2A and SCN3A gene polymorphisms and responsiveness to antiepileptic drugs: a multicenter cohort study and meta-analysis

Haerian BS, Baum L, Kwan P, Tan HJ, Raymond AA, Mohamed Z

Pharmacogenomics, 2013 Jul;14(10):1153-66.
PMID: 23859570 DOI: 10.2217/pgs.13.104

Aim: Approximately a third of newly diagnosed epilepsy patients do not respond to antiepileptic drugs (AEDs). Evidence suggests that low penetrance variants in the genes of drug targets such as voltage-gated sodium channels may be involved in drug responsiveness. To examine this hypothesis, we compared data from two epilepsy cohorts from Malaysia and Hong Kong, as well as a meta-analysis from published data.

Materials & methods: Genotype analysis of 39 polymorphisms located in the SCN1A, SCN2A and SCN3A genes was performed on 1504 epilepsy patients from Malaysia and Hong Kong who were receiving AEDs. Meta-analysis was performed for pooled data of SCN1A rs3812718 and rs2298771, and SCN2A rs17183814 polymorphisms.

Results: Our data from the Hong Kong and Malaysia cohorts showed no significant allele, genotype and haplotype association of polymorphisms in the SCN1A, SCN2A, and SCN3A genes with drug responsiveness in epilepsy. This finding was supported by a meta-analysis for SCN1A rs3812718 and rs2298771, and for SCN2A rs17183814 polymorphisms.

Conclusion: Our comprehensive study suggests that common polymorphisms in SCN1A, SCN2A and SCN3A do not play major roles in influencing response to AEDs.

Matched MeSH terms: NAV1.1 Voltage-Gated Sodium Channel/genetics*