Divergent effects of the T1174S SCN1A mutation associated with seizures and hemiplegic migraine

Sandrine Cestèle, Angelo Labate, Raffaella Rusconi, Patrizia Tarantino, Laura Mumoli, Silvana Franceschetti, Grazia Annesi, Massimo Mantegazza, Antonio Gambardella

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose To report the identification of the T1174S SCN1A (Na V1.1) mutation in a three-generation family with both epileptic and familial hemiplegic migraine (FHM) phenotypes and clarify the pathomechanism. Methods The five affected individuals underwent detailed clinical analyses. Mutation analyses was performed by direct sequencing of SCN1A; functional studies by expression in tsA-201 cells. A computational model was used to compare the effects of T1174S with those of a typical FHM mutation (Q1489K). Key Findings The proband had benign occipital epilepsy (BOE); two relatives had simple febrile seizures (FS) and later developed BOE. Two additional relatives had FHM without epilepsy or FS. All affected members and one obliged carrier carried the T1174S mutation. Functional effects were divergent: positive shift of the activation curve and deceleration of recovery from fast inactivation, consistent with loss of function, and increase of persistent current (I NaP), consistent with gain of function. The INaP increase was inhibited by dialysis of the cytoplasm, consistent with a modulation. Therefore, as shown by the computational model, T1174S could in some conditions induce overall loss of function, and in others gain of function; Q1489K induced gain of function in all the conditions. Significance Modulation of the properties of T1174S can lead to a switch between overall gain and loss of function, consistent with a switch between promigraine end epileptogenic effect and, thus, with coexistence of epileptic and FHM phenotypes in the same family. These findings may help to shed light on the complex genotype-phenotype relationship of SCN1A mutations.

Original languageEnglish
Pages (from-to)927-935
Number of pages9
JournalEpilepsia
Volume54
Issue number5
DOIs
Publication statusPublished - May 2013

Keywords

  • Electrophysiology
  • Epilepsy
  • Febrile seizures
  • Migraine
  • Sodium channel

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology

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