Abstract 13618: Negative Association of H558r Polymorphism and Ventricular Fibrillation in Patients With Brugada Syndrome

Abstract

BACKGROUND: The common SCN5A polymorphism H558R has been reported as a genetic modulator that improves sodium channel activity in mutated channels by repairing abnormal channel gating kinetics and membrane trafficking. We investigated the possible effects of H558R on the clinical manifestations of Brugada syndrome. METHODS: The study population comprised 95 Brugada syndrome patients (mean age 42 ± 14 years, 91 males and 4 females) and 1,875 normal controls. H558R was genotyped by TaqMan assay in all subjects. The SCN5A gene mutation was screened by resequencing. We evaluated the PR, QRS, and QTc intervals from lead II and the J-point amplitude from leads V1 and V2 of a 12-lead electrocardiogram (ECG). We also evaluated signal-averaged ECG and electrophysiological parameters. RESULTS: H558R was less frequent in patients with Brugada syndrome than normal controls (4.7% vs. 10.3%, P = 0.01). Surprisingly, H558R (minor allele A) was not observed in patients with Brugada syndrome without ventricular fibrillation (VF; n = 60), whereas 7.5% of patients with VF had H558R (n = 35). Nonsynonymous mutation of SCN5A was not detected in patients with H558R. The H558R carriers showed lower J-point elevation in lead V1 than noncarriers (1.8 ± 0.4 vs. 3.3 ± 0.3 mV, P = 0.04). Other parameters in the 12-lead and signal-averaged ECG were similar in patients with and without H558R. CONCLUSION: We demonstrated that the H558R polymorphism was a strong protective genetic modulator even in Brugada syndrome patients without SCN5A mutation.