Discovery of TBX20 as a Novel Gene Underlying Atrial Fibrillation

SIMPLE SUMMARY: Atrial fibrillation (AF), the most prevalent sustained dysrhythmia, is accountable for substantial mortality and morbidity. Accumulating convincing evidence highlights the predominant roles of heritable components in the initiation and maintenance of AF. Here, through pan-genomic genotyping with genetic markers followed by a genetic linkage study in an AF family, a novel AF-causing locus was located at human chromosome 7p14.2–p14.3. An exome-wide sequence assay unveiled that, at the defined locus, the mutation in TBX20, NM_001077653.2: c.695A>G; p.(His232Arg), was solely co-segregated with AF in the family. Additionally, a Sanger sequencing assay of TBX20 in another AF family uncovered a novel mutation, NM_001077653.2: c.862G>C; p.(Asp288His). Neither of the two mutations were found in 600 control persons. Functional investigations demonstrated that the two mutations both significantly reduced the transactivation of the target gene KCNH2 and the ability to bind the promoter of KCNH2, while they had no effect on the nuclear distribution of TBX20. These findings strongly indicate that TBX20 is a new AF-predisposing gene, shedding light on the mechanism underlying AF and suggesting clinical significance for the individually tailored treatment of AF. ABSTRACT: Atrial fibrillation (AF), the most prevalent type of sustained cardiac dysrhythmia globally, confers strikingly enhanced risks for cognitive dysfunction, stroke, chronic cardiac failure, and sudden cardiovascular demise. Aggregating studies underscore the crucial roles of inherited determinants in the occurrence and perpetuation of AF. However, due to conspicuous genetic heterogeneity, the inherited defects accounting for AF remain largely indefinite. Here, via whole-genome genotyping with genetic markers and a linkage assay in a family suffering from AF, a new AF-causative locus was located at human chromosome 7p14.2-p14.3, a ~4.89 cM (~4.43-Mb) interval between the markers D7S526 and D7S2250. An exome-wide sequencing assay unveiled that, at the defined locus, the mutation in the TBX20 gene, NM_001077653.2: c.695A>G; p.(His232Arg), was solely co-segregated with AF in the family. Additionally, a Sanger sequencing assay of TBX20 in another family suffering from AF uncovered a novel mutation, NM_001077653.2: c.862G>C; p.(Asp288His). Neither of the two mutations were observed in 600 unrelated control individuals. Functional investigations demonstrated that the two mutations both significantly reduced the transactivation of the target gene KCNH2 (a well-established AF-causing gene) and the ability to bind the promoter of KCNH2, while they had no effect on the nuclear distribution of TBX20. Conclusively, these findings reveal a new AF-causative locus at human chromosome 7p14.2-p14.3 and strongly indicate TBX20 as a novel AF-predisposing gene, shedding light on the mechanism underlying AF and suggesting clinical significance for the allele-specific treatment of AF patients.