178 BIOMEDICAL REPORTS 4: 178-182, 2016 Association of genetic variants with atrial fibrillation YUICHIRO YAMASE1, KIMIHIKO KATO2, HIDEKI HORIBE1, CHIKARA UEYAMA1, TETSUO FUJIMAKI3, MITSUTOSHI OGURI4, MASAZUMI ARAI5, SACHIRO WATANABE5, TOYOAKI MUROHARA6 and YOSHIJI YAMADA7 1Department of Cardiovascular Medicine, Gifu Prefectural Tajimi Hospital, Tajimi, Gifu 507‑8522; 2Department of Internal Medicine, Meitoh Hospital, Nagoya, Aichi 465‑0025; 3Department of Cardiovascular Medicine, Inabe General Hospital, Inabe, Mie 511‑0428; 4Department of Cardiology, Kasugai Municipal Hospital, Kasugai, Aichi 486‑8510; 5Department of Cardiology, Gifu Prefectural General Medical Center, Gifu, Gifu 500‑8717; 6Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466‑8550; 7Department of Human Functional Genomics, Life Science Research Center, Mie University, Tsu, Mie 514‑8507, Japan Received October 1, 2015; Accepted November 27, 2015 DOI: 10.3892/br.2015.551 Abstract. Recent genome-wide association studies (GWASs) with atrial fibrillation, with the minor G and T alleles, respec- identified various genes and loci that confer susceptibility tively, representing risk factors for this condition. PSRC1 and to coronary artery disease or myocardial infarction among ZC3HC1 may thus be susceptibility loci for atrial fibrillation in Caucasian populations. As myocardial ischemia is an impor- Japanese individuals. tant risk factor for atrial fibrillation, we hypothesized that certain polymorphisms may contribute to the genetic suscep- Introduction tibility to atrial fibrillation through affecting the susceptibility to coronary artery disease. The aim of the present study was to Atrial fibrillation (AF) is the most common cardiac arrhythmia examine the possible association of atrial fibrillation in Japanese with a major public health problem. The estimated number individuals with 29 polymorphisms identified as susceptibility of individuals with AF worldwide in 2010 was 33.5 million loci for coronary artery disease or myocardial infarction in the (20.9 million men and 12.6 million women) (1). The prevalence meta-analyses of GWASs in Caucasian populations. The study of AF is increasing and is estimated to double by 2050 in the subjects comprised 5,470 Japanese individuals (305 subjects United States (2). AF is associated with an increased risk for with atrial fibrillation and 5,165 controls). Genotypes for heart failure, thromboembolic diseases such as cardioembolic 29 polymorphisms were determined by a method that combines stroke, and mortality (3,4), resulting in large public health the polymerase chain reaction and sequence‑specific oligonu- costs (5). Although the molecular mechanism of AF is complex cleotide probes with suspension array technology. Comparisons and has not been determined definitively, several risk factors, of the allele frequencies by the χ2 test revealed that rs599839 including aging, male gender, smoking, obesity, hypertension, (G→A) of the proline/serine-rich coiled-coil 1 gene (PSRC1, diabetes mellitus, valvular heart disease, coronary artery P=0.0084) and rs11556924 (C→T, Arg363His) of the zinc disease and heart failure, have been clinically determined (6). finger, C3HC‑type containing 1 gene (ZC3HC1, P=0.0076) In addition to these conventional risk factors, recent studies were significantly (P<0.01) associated with atrial fibrillation. have shown the importance of genetic factors in the develop- Multivariable logistic regression analysis with adjustment for ment of AF (7). Genome‑wide association studies (GWASs) age, gender, body mass index, estimated glomerular filtration have identified several genes and loci that confer susceptibility rate, and the prevalence of smoking, hypertension, diabetes to AF (8‑11). These genes include those for transcription mellitus, and dyslipidemia revealed that rs599839 (P=0.0043; factors associated with cardiopulmonary development, cardiac odds ratio, 1.56; dominant model) and rs11556924 (P=0.0043; ion channels, and cell signaling molecules (11). odds ratio, 1.93; dominant model) were significantly associated Recent GWASs also identified various genes and loci that confer susceptibility to coronary artery disease or myocar- dial infarction among Caucasian populations (12,13). As myocardial ischemia is an important risk factor for AF (6), we hypothesized that certain polymorphisms may contribute to Correspondence to: Professor Yoshiji Yamada, Department the genetic susceptibility to AF through affecting the suscepti- of Human Functional Genomics, Life Science Research Center, Mie University, 1577 Kurima‑machiya, Tsu, Mie 514‑8507, Japan bility to coronary artery disease. The aim of the present study E-mail: [email protected] was to examine the possible association of AF in Japanese individuals with 29 single nucleotide polymorphisms (SNPs) Key words: genetics, genetic variant, polymorphism, atrial identified as susceptibility loci for coronary artery disease fibrillation, arrhythmia or myocardial infarction by the meta-analyses of GWASs in Caucasian populations (12,13). YAMASE et al: GENETIC VARIANTS AND ATRIAL FIBRILLATION 179 Materials and methods Table I. Characteristics of subjects with atrial fibrillation and controls. Study population. The study subjects comprised 5,470 Japanese individuals (305 subjects with AF, 5,165 controls), who either Atrial visited outpatient clinics of, or were admitted to, the partici- Characteristics fibrillation Control P‑value pating hospitals (Gifu Prefectural Tajimi Hospital, Tajimi; Subjects, n 305 5,165 Gifu Prefectural General Medical Center, Gifu; Inabe General Age, years 66.4±10.4 64.4±11.2 0.0038 Hospital, Inabe; Japanese Red Cross Nagoya First Hospital, Gender, % (men/women) 82.0/18.0 59.2/40.8 <0.0001 Nagoya; Hirosaki University Hospital and Hirosaki Stroke Body mass index, kg/m2 23.4±3.8 23.8±3.5 0.0310 Center, Hirosaki, Japan) between 2002 and 2012, due to Current or former smoker, % 24.8 28.4 0.1804 various symptoms or for an annual health checkup. Subjects Hypertension, % 70.5 60.7 0.0006 with AF who had apparent structural heart diseases, including Diabetes mellitus, % 40.3 34.7 0.0458 severe valvular heart disease, hypertrophic or dilated cardio- Dyslipidemia, % 39.0 43.3 0.1447 myopathy, and congenital heart disease, were excluded from Hyperuricemia, % 10.6 4.6 <0.0001 the study. The 5,165 control individuals had no history of AF Chronic kidney disease, % 81.8 69.9 0.0024 or other significant supraventricular or ventricular arrhyth- eGFR, ml min-1 1.73 m-2 66.0±19.1 68.6±24.6 0.0022 mias, or of taking antiarrhythmic medication. The study protocol complied with the Declaration of Quantitative data are mean ± standard deviation. Hypertension: Systolic Helsinki and was approved by the Committees on the Ethics blood pressure of ≥140 mmHg or diastolic blood pressure of ≥90 mmHg, or under antihypertensive medication. Diabetes mellitus: Fasting plasma glucose of Human Research of Mie University Graduate School of level of ≥6.93 mmol/l or blood glycosylated hemoglobin (hemoglobin A1c) Medicine, Hirosaki University Graduate School of Medicine, content of ≥6.5%, or under antidiabetes medication. Dyslipidemia: Serum and participating hospitals. Written informed consent was concentration of triglyceride of ≥1.65 mmol/l, a serum high‑density lipopro- obtained from each participant. tein‑cholesterol of <1.04 mmol/l, a serum low‑density lipoprotein‑cholesterol of ≥3.64 mmol/l, or under antidyslipidemic medication. Hyperuricemia: Serum concentration of uric acid of ≥416.4 µmol/l or under antihyperuricemic Selection and genotyping of polymorphisms. SNPs that were medication. Chronic kidney disease: eGFR of <60 ml min-1 1.73 m-2: eGFR shown to be significantly associated with coronary artery disease (ml min-1 1.73 m-2) = 194 x [age (years)]-0.287 x [serum creatinine (mg/dl)]-1.094 or myocardial infarction were searched for in Caucasian popula- (x 0.739, if female). eGFR, estimated glomerular filtration rate. tions by the meta‑analyses of GWASs (12,13). These SNPs were examined with the SNP database (dbSNP; National Center for Biotechnology Information, Bethesda, MD, USA) to identify SNPs with a minor allele frequency of ≥0.015 in a Japanese (0, no history; 1, positive history), and each genotype; and the population. A total of 29 SNPs (14) were finally selected and the P-value, odds ratio and 95% confidence interval were calculated. possible association with AF was examined. The ancestral and Genotypes of each polymorphism were assessed according to variant alleles of the SNPs were determined from the dbSNP. dominant [0, AA; 1, AB + BB (A, major allele; B, minor allele)], Venous blood (7 ml) was collected into tubes containing recessive (0, AA + AB; 1, BB), and additive genetic models. 50 mmol/l ethylenediaminetetraacetic acid (disodium salt), Additive models comprised additive 1 (0, AA; 1, AB; 0, BB) and the peripheral blood leukocytes were isolated, and genomic additive 2 (0, AA; 0, AB; 1, BB) models, which were analyzed DNA was extracted from these cells with a DNA extraction kit simultaneously with a single statistical model. A stepwise (Genomix; Talent Srl, Trieste, Italy). Genotypes of SNPs were forward selection procedure was also performed to examine determined at G&G Science Co., Ltd. (Fukushima, Japan) by the effects of genotypes, as well as other covariates on AF. The a method that combines the polymerase chain reaction and P-values for inclusion in and exclusion from the model were 0.25 sequence‑specific oligonucleotide