CAV1-A Susceptibility Gene for Atrial Fibrillation: The Impact of Coding and Noncoding Variants.

BACKGROUND: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia with a strong genetic predisposition. Genome-wide association studies have highlighted CAV1 (caveolin 1), a caveolar protein involved in various signaling pathways, as a candidate for cardiac conduction disorders. METHODS: We explored the role of CAV1 in AF in various models to dissect possible disease mechanisms. First, CAV1 expression was examined together with the AF risk gene SHOX2 in a porcine model of induced AF. Then we screened a cohort of 282 patients with early-onset AF to identify genetic variants within CAV1 and found 1 coding and 5 noncoding variants. The coding variant was functionally investigated in zebrafish, and a comprehensive analysis panel was applied to investigate the noncoding variants. RESULTS: In the porcine AF model, CAV1 and SHOX2 were significantly downregulated in the right atrium and atrioventricular node. Cardiac-specific overexpression of the coding variant in zebrafish increased heart rate and caused fibrillatory waves and loss of the PR interval, supporting a pathogenic effect. Four of the 5 novel identified noncoding variants showed an association with AF and PR interval in published data sets, including 1 with genome-wide significance. The noncoding variants localized to binding sites of transcription factors EOMES, RFX5, TEAD4 and MAX. Luciferase reporter gene assays demonstrated that 3 variants significantly altered the ability of those transcription factors to activate reporter gene expression. CONCLUSIONS: This work underscores CAV1 as an AF susceptibility gene and highlights the critical role of coding and noncoding variants in AF disease mechanisms.