Authors: Philippe Maury Adrien Moreau Francoise HiddenLucet Antoine Leenhardt Veronique Fressart Myriam Berthet Isabelle Denjoy Nawal Bennamar Anne Rollin Christelle Cardin Pascale Guicheney Mohamed Chahine
Publish Date: 2013/04/24
Volume: 37, Issue: 2, Pages: 131-140
Abstract
Brugada syndrome BrS is an inherited cardiac disease characterized by ST segment elevation in V1–V3 ECG leads Mutations SCN5A gene encoding for the cardiac voltagegated Na+ channel are found in some BrS patients but also in family members with isolated conduction disturbances However some patients show coved ST elevation in the inferior or lateral leads whose association with SCN5A and familial conduction disturbances are poorly knownTwo novel SCN5A mutations D1430N and Q1476X were identified in two unrelated families comprising patients with Brugadalike ST elevation located in the inferior leads or isolated conduction disturbances Wildtype WT and D1430N mutant channels were expressed in tsA201 cells Patch clamp electrophysiological experiments revealed total absence of Na+ current resulting from Nav15 mutant when compared to WT channels Treatments known to restore trafficking defect incubation at low temperature with mexiletine or lidocaine did not restore Na+ current supporting that Nav15 mutation is not a defective trafficking mutation Furthermore immunocytolabelling indicates the membrane localisation of both WT and mutant channels confirming what we observed in our patch clamp experiments This suggests that the mutation may induce a complete block of Na+ permeation The nonsense mutation Q1476X was leading to a premature stop codon and was not expressedBrugadalike ST elevation in the inferior ECG leads or isolated conduction disturbances were found in two unrelated families and associated with two novel SCN5A mutations The missense and nonsense mutations are both resulting in a complete loss of ventricular Na+ current explaining the phenotypes
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