Genetic Polymorphism of KCNH2 Confers Predisposition of Acquired Atrial Fibrillation in Chinese

Discovery of TBX20 as a Novel Gene Underlying Atrial Fibrillation

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.

The Values of Coronary Circulating miRNAs in Patients with Atrial Fibrillation

The mechanism of miRNA regulation in atrial fibrillation (AF) occurrence and development is still unclear, especially, the regulating values of coronary circulating miRNAs has not been reported. Based on our AF radiofrequency ablation clinical practice and previous miRNA study, we proposed a hypothesis that the coronary circulating miRNA might much better reflect the regulating state and metabolic level of myocardial miRNA in AF patient. To investigate the regulating values of coronary circulation miRNA, 90 AF patients were selected and compared with 90 healthy subjects, the changes of coronary circulating miRNA differential expression profile in the whole genome were observed in this study. We found out that compared with autologous peripheral blood (PB), 6 miRNAs were upregulated and 8 miRNA downregulated in AF patients' coronary sinus blood (CSB) significantly, especially, the expression of miR-1266, miR-4279 and miR-4666a-3p were obviously increased. Compared with normal donors' peripheral blood, 16 miRNAs were upregulated and 24 miRNAs downregulated dramatically in patients' peripheral blood, among them, the miR-3171 decreased, but miR-892a and miR-3149 increased significantly from the early to end stages of AF. Our results indicated that the coronary circulating miRNA can really reflect the regulating values of miRNA in AF patient; the level of miRNA change in 3 types of AF may reflect the severity of AF clinical and pathophysiological advance; The miR-892a, miR-3171 and miR-3149 may be used as biomarkers for earlier diagnosis, while miR-1266, miR-4279 and miR-4666a-3p may serve as potential intervening targets for AF patient in future.

Genetic variants of potassium voltage-gated channel genes (KCNQ1, KCNH2, and KCNE1) affected the risk of atrial fibrillation in elderly patients

BACKGROUND

Atrial fibrillation (AF) is a common type of cardiac arrhythmia and is a major healthcare burden. Around 20% of patients show no obvious clinical manifestations; this can lead to a delay of AF diagnosis and prevention. Genetic mutations are one of the important risk factors for AF. This study aimed to assess the associations between polymorphisms on KCNE1, KCNQ1, and KCNH2 with the risk of AF in a Chinese population.

MATERIALS AND METHODS

A case-control study comprised of 438 AF patients and 450 controls. The tag single-nucleotide polymorphisms (SNPs) were retrieved in the International HapMap database and Haploview software was used to capture all the polymorphisms on KCNE1, KCNQ1, and KCNH2. DNA was extracted from blood and polymerase chain reaction-based assays were used to genotype polymorphisms of the KCNE1, KCNQ1, and KCNH2 genes. Chi-square test and student t-tests were used to evaluate the differences in the clinical characteristics between AF cases and controls. Odds ratios (OR) and corresponding 95% confidence intervals (CIs) were calculated to assess the association between genetic variants of KCNQ1, KCNH2, KCNE1, and AF risk.

RESULTS

Among the nine tag SNPs, three were significantly associated with the risk of AF: the rs1805127*G allele on KCNE1, and the rs2283228*C and rs1057128*A alleles on KCNQ1. In contrast, rs1805120*T variant was correlated with lower risk of AF. However, the other five genetic variants (rs2237892, rs2237895, rs2237897, rs2070357, and rs2070356) showed no significant association with AF risk (all p>0.05).

CONCLUSIONS

Our study suggested that the rs1805127*G allele of KCNE1, and the rs2283228*C and rs1057128*A alleles on KCNQ1 are risk factors for AF, while the rs1805120*T allele on KCNH2 may serve as a protective factor for AF.

Association of KCNE1 genetic polymorphisms with atrial fibrillation in a Chinese Han population

OBJECTIVE

The purpose of this study was to investigate the association of the polymorphisms of the KCNE1 gene with atrial fibrillation (AF) in a Chinese Han population.

METHODS

Three hundred seven AF patients and 330 age- and sex-matched controls were genotyped using the polymerase chain reaction-restriction fragment length polymorphism method for two single-nucleotide polymorphisms (rs1805127 and rs1892593) of the human KCNE1 gene.

RESULTS

The frequencies of the AA, AG, and GG genotypes of rs1805127 were 11.7%, 50.0%, and 43.3%, respectively, in the AF group, whereas the ones in the control group had frequencies of 19.4%, 44.9%, and 35.8%, respectively. There were significant differences in frequencies of these three genotypes (χ(2)=7.820, p=0.016) and G allele (65.8% vs. 58.2%; χ(2)=8.266, p=0.005). The frequencies of AA, AG, and GG of rs1892593 were 38.4%, 47.9%, and 13.7% in the AF group, whereas the ones in the control group had frequencies of 37.8%, 48.5%, and 14.0%, respectively. There was no difference in distributions of frequencies of these three genotypes and allele (χ(2)=0.051, p=0.978; χ(2)=1.024, p=0.837, respectively) between AF patients and control subjects. We also found that rs1805127 was associated with left atrial diameter and left ventricular end diastolic diameter in AF patients (χ(2)=24.883, p<0.001; χ(2)=34.901, p<0.001, respectively). Logistic regression analysis showed that rs1805127 was an independent risk factor of AF in a Chinese Han population (odds ratio [OR]=1.66, 95% confidence interval [CI]: 1.02-2.68 for AG; OR=2.03, 95% CI: 1.24-3.31 for GG).

CONCLUSION

The genetic polymorphism of KCNE1 was associated with increased risk of AF in a Chinese Han population.