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Introduction: Brugada Syndrome (BrS) is a disorder associated with an increased risk of sudden cardiac death and specific ECG features consisting of ST-segment elevation in the right precordial leads. Loss-of-function mutations in SCN5A underlie the disorder in ∼25% of patients. While other genes have been implicated, these account for <1% of subjects. Thus the genetic basis of BrS remains unknown in the majority of cases. We here set out to identify the genetic defect underlying BrS in a 3 generation family from Ireland with a case of spontaneous type 1 ECG who died suddenly at 24 years old.Methods: Exome sequencing was carried out in 3 individuals from the pedigree using Agilent SureSelect Target Enrichment 50Mb capture followed by sequencing on an Illumina HiSeq 2000. These 3 individuals were selected based on their genetic distance and the presentation of a BrS ECG at baseline.Results: Comparison of 3 exomes from affected individuals identified 22,171 shared variants. Filtering out of variants occurring at a minor allele frequency (MAF) of >1% in public and in-house exome/genome databases, and considering all types of exonic variants and splice site variants, resulted in 10 rare variants shared among the 3 affected. Two of the variants are found in all afffected family members and not in the unaffected and reside in 2 different genes, namely HOOK3 and PXDNL. These 2 variants have been found at a MAF of 0.02% and 0.008%, respectively, in the NHLBI Exome Variant Project population (n=6500 individuals). The function of PXDNL, which appears to be specifically expressed in heart, is yet unknown. The PXDNL variant is predicted to be deleterious and probably damaging by SIFT and Polyphen2 algorithms, respectively.Conclusions: We identified by exome sequencing a chromosomal interval and a possible novel gene for BrS. Ongoing functional studies are aimed at investigating further the involvement of this gene in the BrS. [ABSTRACT FROM PUBLISHER]

Aims: Brugada syndrome (BrS) remains genetically heterogeneous and is associated with slowed cardiac conduction. We aimed to identify genetic variation in BrS cases at loci associated with QRS duration., Methods and Results: A multi-centre study sequenced seven candidate genes (SCN10A, HAND1, PLN, CASQ2, TKT, TBX3, and TBX5) in 156 Caucasian SCN5A mutation-negative BrS patients (80% male; mean age 48) with symptoms (64%) and/or a family history of sudden death (47%) or BrS (18%). Forty-nine variants were identified: 18 were rare (MAF <1%) and non-synonymous; and 11/18 (61.1%), mostly in SCN10A, were predicted as pathogenic using multiple bioinformatics tools. Allele frequencies were compared with the Exome Sequencing and UK10K Projects. SKAT methods tested rare variation in SCN10A finding no statistically significant difference between cases and controls. Co-segregation analysis was possible for four of seven probands carrying a novel pathogenic variant. Only one pedigree (I671V/G1299A in SCN10A) showed co-segregation. The SCN10A SNP V1073 was, however, associated strongly with BrS [66.9 vs. 40.1% (UK10K) OR (95% CI) = 3.02 (2.35-3.87), P = 8.07 × 10-19]. Voltage-clamp experiments for NaV1.8 were performed for SCN10A common variants V1073, A1073, and rare variants of interest: A200V and I671V. V1073, A200V and I671V, demonstrated significant reductions in peak INa compared with ancestral allele A1073 (rs6795970)., Conclusion: Rare variants in the screened QRS-associated genes (including SCN10A) are not responsible for a significant proportion of SCN5A mutation negative BrS. The common SNP SCN10A V1073 was strongly associated with BrS and demonstrated loss of NaV1.8 function, as did rare variants in isolated patients., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.)