SCN1A IVS5N+5 polymorphism and response to sodium valproate: a multicenter study

Abstract

Aim: 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. Patients & methods: The SCN1A IVS5N+5 polymorphism was genotyped in 583 Malaysian (84%) and Hong Kong Chinese (16%) epilepsy patients receiving VPA monotherapy. The related association studies, including the current study, were meta-analyzed by using fixed- and random-effects models under various genetic models. Results: A total of 277 (47.5%) and 306 (52.5%) patients were VPA nonresponsive and responsive, respectively. Unlike Chinese and Indian patients, Malay nonresponsive patients with idiopathic generalized epilepsy showed significant association, probably caused by the small sample size. Conclusion: The cohort study and meta-analysis did not demonstrate an association between AED responsiveness and this polymorphism. Future studies with a larger sample size of Malays with idiopathic generalized epilepsy are suggested. Original submitted 15 June 2012; Revision submitted 23 July 2012