Atrial fibrillation (AF) is the most common arrhythmia in the clinical setting and an independent risk factor for stroke. Approximately 10 million Chinese people are affected by AF, but the genetic basis is largely unknown. A recent genome-wide association study in Iceland identified association between SNP rs2200733 on 4q25 and AF; however, many independent replication studies are essential to unequivocally validate this association. To assess the association between rs2200733 and AF as well as that between rs2200733 and ischemic stroke in a mainland Chinese Han population, we carried out case-control association studies with 383 AF patients versus 851 non-AF controls and 811 ischemic stroke patients versus 688 non-stroke controls. Highly significant association was detected between rs2200733 and AF in a Chinese Han population (allelic P = 3.7 × 10(-11) with OR = 1.81; genotypic P = 4.1 × 10(-12) with a dominant model). When the AF cases were divided into lone AF (32.6%) and other types of AF (67.4%), significantly stronger association was found with lone AF (OR = 2.40, P = 1.3 × 10(-9) compared to OR = 1.59, P = 6.2 × 10(-7) for other types of AF; P = 0.02 for two ORs). No significant association was found between rs2200733 and ischemic stroke. Our results suggest that SNP rs2200733 confers a highly significant risk of AF, but not ischemic stroke, in a more representative Chinese Han population in the mainland China.

Atrial fibrillation (AF) is the most common cardiac rhythm disorder at the clinical setting and accounts for up to 15% of all strokes. Recent genome-wide association studies (GWAS) identified two single nucleotide polymorphisms (SNPs), rs2106261 and rs7193343 in ZFHX3 (zinc finger homeobox 3 gene) and rs13376333 in KCNN3 (encoding a potassium intermediate/small conductance calcium-activated channel, subfamily N, member 3) that showed significant association with AF in multiple populations of European ancestry. Here, we studied a Chinese Han, GeneID cohort consisting of 650 AF patients and 1,447 non-AF controls to test whether the GWAS findings on ZFHX3/KCNN3 and AF can be expanded to a different ethnic population. No significant association was detected for rs7193343 in ZFHX3 and rs13376333 in KCNN3. However, significant association was identified between rs2106261 in ZFHX3 and AF in the GeneID population for both allelic frequencies (P = 0.001 after adjusting for covariates of age, gender, hypertension, coronary artery disease, and diabetes mellitus; OR = 1.32), and genotypic frequencies assuming either an additive or recessive model (OR = 1.29, P = 0.001 and OR = 1.77, P = 0.00018, respectively). When only lone AF cases were analyzed, the association remained significant (OR = 1.50, P = 0.001 for allelic association; OR = 1.45, P = 0.001 for an additive model; OR = 2.24, P = 0.000043 for a recessive model). Our results indicate that rs2106261 in ZFHX3 confers a significant risk of AF in a Chinese Han population. The study expands the association between ZFHX3 and AF to a non-European ancestry population and provides the first evidence of a cross-race susceptibility of the 16q22 AF locus.

Accumulating evidence reveals that genetic variants play pivotal roles in familial atrial fibrillation (AF). However, the molecular defects in most patients with AF remain to be identified. Here, we report on three novel KCNA5 mutations that were identified in 4 of 120 unrelated AF families. Among them, T527M was found in two AF families, and A576V and E610K in two other AF families, respectively. The mutations T527M and A576V were also detected in 2 and 1 of 256 patients with idiopathic AF, respectively. The same mutations were not observed in 200 secondary AF patients and 500 controls. Functional analyses revealed consistent loss-of-function effects of mutant KCNA5 proteins on the ultrarapidly activating delayed rectifier potassium currents. These findings expand the spectrum of mutations in KCNA5 linked to AF and provide new insight into the molecular mechanism involved in AF.

Atrial fibrillation (AF) is the most common cardiac arrhythmia at the clinic. Recent GWAS identified several variants associated with AF, but they account for <10% of heritability. Gene-gene interaction is assumed to account for a significant portion of missing heritability. Among GWAS loci for AF, only three were replicated in the Chinese Han population, including SNP rs2106261 (G/A substitution) in ZFHX3, rs2200733 (C/T substitution) near PITX2c, and rs3807989 (A/G substitution) in CAV1. Thus, we analyzed the interaction among these three AF loci. We demonstrated significant interaction between rs2106261 and rs2200733 in three independent populations and combined population with 2,020 cases/5,315 controls. Compared to non-risk genotype GGCC, two-locus risk genotype AATT showed the highest odds ratio in three independent populations and the combined population (OR=5.36 (95% CI 3.87-7.43), P=8.00×10-24). The OR of 5.36 for AATT was significantly higher than the combined OR of 3.31 for both GGTT and AACC, suggesting a synergistic interaction between rs2106261 and rs2200733. Relative excess risk due to interaction (RERI) analysis also revealed significant interaction between rs2106261 and rs2200733 when exposed two copies of risk alleles (RERI=2.87, P<1.00×10-4) or exposed to one additional copy of risk allele (RERI=1.29, P<1.00×10-4). The INTERSNP program identified significant genotypic interaction between rs2106261 and rs2200733 under an additive by additive model (OR=0.85, 95% CI: 0.74-0.97, P=0.02). Mechanistically, PITX2c negatively regulates expression of miR-1, which negatively regulates expression of ZFHX3, resulting in a positive regulation of ZFHX3 by PITX2c; ZFHX3 positively regulates expression of PITX2C, resulting in a cyclic loop of cross-regulation between ZFHX3 and PITX2c. Both ZFHX3 and PITX2c regulate expression of NPPA, TBX5 and NKX2.5. These results suggest that cyclic cross-regulation of gene expression is a molecular basis for gene-gene interactions involved in genetics of complex disease traits.

Background The CAV1 gene encodes caveolin-1 expressed in cell types relevant to atherosclerosis. Cav-1-null mice showed a protective effect on atherosclerosis under the ApoE−/− background. However, it is unknown whether CAV1 is linked to CAD and MI in humans. In this study we analyzed a tagSNP for CAV1 in intron 2, rs3807989, for potential association with CAD. Methods and Results We performed case-control association studies in three independent Chinese Han populations from GeneID, including 1,249 CAD cases and 841 controls in Population I, 1,260 cases and 833 controls in Population II and 790 cases and 1,212 controls in Population III (a total of 3,299 cases and 2,886 controls). We identified significant association between rs3807989 and CAD in three independent populations and in the combined population (Padj=2.18×10−5, OR=1.19 for minor allele A). We also detected significant association between rs3807989 and MI (Padj=5.43×10−5, OR=1.23 for allele A). Allele A of SNP rs3807989 was also associated with a decreased level of LDL cholesterol. Although rs3807989 is a tagSNP for both CAV1 and nearby CAV2, allele A of SNP rs3807989 was associated with an increased expression level of CAV1 (both mRNA and protein), but not CAV2. Conclusions The data in this study demonstrated that rs3807989 at the CAV1/CAV2 locus was associated with significant risk of CAD and MI by increasing expression CAV1 (but not CAV2). Thus, CAV1 becomes a strong candidate susceptibility gene for CAD/MI in humans.

Atrial fibrillation (AF) is the most common cardiac arrhythmia in the clinic, and accounts for more than 15% of strokes. Mutations in cardiac sodium channel α, β1 and β2 subunit genes (SCN5A, SCN1B, and SCN2B) have been identified in AF patients. We hypothesize that mutations in the sodium channel β3 subunit gene SCN3B are also associated with AF. To test this hypothesis, we carried out a large scale sequencing analysis of all coding exons and exon-intron boundaries of SCN3B in 477 AF patients (28.5% lone AF) from the GeneID Chinese Han population. A novel A130V mutation was identified in a 46 year-old patient with lone AF, and the mutation was absent in 500 controls. Mutation A130V dramatically decreased the cardiac sodium current density when expressed in HEK293/Na v 1.5 stable cell line, but did not have significant effect on kinetics of activation, inactivation, and channel recovery from inactivation. When co-expressed with wild type SCN3B, the A130V mutant SCN3B negated the function of wild type SCN3B, suggesting that A130V acts by a dominant negative mechanism. Western blot analysis with biotinylated

ObjectivesTo investigate the effects of gender on the association of serum uric acid (SUA) levels and atrial fibrillation (AF) prevalence in a community-based Chinese population.SettingData were obtained from annual Jidong Oilfield employee and family member health checkups. The Jidong community is geographically located in Tangshan City in northern China.ParticipantsA total of 9078 residents were invited to take part in the survey and provided informed consents. Individuals without data of ECG or SUA were excluded, leaving 8937 residents in our study.Primary and secondary outcome measuresSUA was measured at baseline using the uricase-peroxidase method. Hyperuricaemia was defined as a SUA level >7.0 mg/dL in men and >5.7 mg/dL in women. AF was diagnosed based on ECG findings and/or any medical history of AF from referring physicians. The crude and independent association between SUA levels and AF prevalence was evaluated with logistic regression analysis.ResultsAF prevalence was 0.6% (53/8937). Participants with hyperuricaemia had a higher AF prevalence compared with those with normal SUA levels (1.1% vs 0.5%; P=0.02). Hyperuricaemia was correlated with AF after adjustment for various cardiovascular risk factors in all participants (P=0.03, OR 2.051, 95% CI 1.063 to 3.856). This correlation was particularly stronger in women compared with men (P<0.001, OR 6.366, 95% CI 2.553 to 15.871 in women and P=0.96, OR 1.025, 95% CI 0.400 to 2.626 in men).ConclusionsWe demonstrated a significant association between increased SUA levels and AF prevalence in a Chinese population. Our data indicate that there is a gender-specific mechanism underlying the relationship between SUA and AF.

No abstract