Spectrum and Prevalence of Mutations Involving BrS1- Through BrS12-Susceptibility Genes in a Cohort of Unrelated Patients Referred for Brugada Syndrome Genetic Testing

Abstract

Objective To provide the spectrum and prevalence of mutations in the 12 Brugada Syndrome (BrS)-susceptibility genes discovered to date, in a single large BrS cohort. Background BrS is a potentially lethal heritable arrhythmia syndrome diagnosed electrocardiographically by coved-type ST segment elevation in the right precordial leads (V1-V3; type-1 Brugada ECG pattern) and the presence of a personal/family history of cardiac events. Methods Using PCR, DHPLC, and DNA sequencing, comprehensive mutational analysis of BrS1-12-susceptibility genes was performed in 129 unrelated patients with possible/probable BrS [46 with clinically diagnosed BrS (ECG pattern plus personal/family history of a cardiac event) and 83 with type 1 ECG pattern only]. Results Overall, 27 (21%) patients had a putative pathogenic mutation, absent in 1400 Caucasian reference alleles, including 21 patients with an SCN5A mutation, 2 CACNB2B, 1 KCNJ8, 1 KCND3, 1 SCN1Bb, and 1 HCN4. The overall mutation yield was 23% in type 1 ECG pattern only patients versus 17% in clinically diagnosed BrS patients, was significantly greater among young men < 20 years of age with clinically diagnosed BrS, and among patients who had a prolonged PQ interval. Conclusions We identified putative pathogenic mutations in ~20% of our BrS cohort, with BrS2-12 accounting for < 5%. Importantly, the yield was similar between patients with only a type 1 BrS ECG pattern and those with clinically established BrS. The yield approaches 40% for SCN5A-mediated BrS (BrS1) when the PQ interval exceeds 200ms. Calcium channel-mediated BrS is extremely unlikely in the absence of a short QT interval.