Int J Clin Exp Med 2015;8(1):1188-1196 www.ijcem.com /ISSN:1940-5901/IJCEM0003312 Original Article Common variant rs7597774 in ADD2 is associated with dilated cardiomyopathy in Chinese Han population Fei F Chen1*, Yun L Xia1*, Cheng Q Xu2, Si S Li2, Yuan Y Zhao2, Xiao J Wang2, Shan S Chen2, Lian J Gao1, Yang Zhong3, Xin Tu2, Qing Wang2,4, Yan Z Yang1 1Department of Cardiology, First Affiliated Hospital of Dalian Medical University, Dalian, China; 2College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technol- ogy, Wuhan, China; 3Department of Cardiology, Fifth People’s Hospital of Dalian, Dalian, China; 4Department of Molecular Cardiology, Center for Cardiovascular Genetics, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA. *Equal contributors. Received October 21, 2014; Accepted January 7, 2015; Epub January 15, 2015; Published January 30, 2015 Abstract: Two polymorphisms, rs7597774 and rs1739843 in ADD2 and HSPB7 respectively, were found to be as- sociated with dilated cardiomyopathy (DCM) in European cohorts but the results were not validated in the Chinese Han population. We aimed to test the association of the two variants with DCM in a cohort of Chinese Han popula- tion. DCM (399) and control (1384) individuals were identified from the GeneID database in China, and DNA was isolated from peripheral blood lymphocytes for genotyping. Alleles were amplified by PCR, and amplicons harboring polymorphisms rs1739843 and rs7597774 were directly genotyped using high-resolution melting analysis. Sta- tistical analysis was subsequently performed to evaluate the association of the variants with DCM. Allelic analysis demonstrated that rs7597774 was significantly related to DCM (P = 0.0157), and an increased risk of DCM was -adj specifically associated with the minor allele A (OR = 1.582). High-grade cardiac dysfunction (NYHA III/IV) was a clini- cal parameter significantly associated with the rs7597774 genotypes AA + AC relative to genotype CC (P = 0.021). Furthermore, DCM patients with the rs7597774 genotype AA tended to undergo more invasive medical interven- tions than those with the genotype CC (P = 0.008). No association was detected between rs1739843 and DCM under any allelic (P = 0.407, OR = 0.920) or genotypic model. In the Chinese Han population, rs7597774 but not -adj rs1739843 was found to be associated with DCM. This study is the first to demonstrate that underlying genotypes of rs7597774 may assist in assessing the heart functional status of DCM patients and also in the prediction of the benefit of particular therapies for these patients. Keywords: ADD2, dilated cardiomyopathy, HSPB7, NYHA heart functional classification, polymorphisms, therapeu- tic regimens Introduction fied in monogenic forms of DCM, with most of them encoding cytoskeletal, sarcomeric, and Dilated cardiomyopathy (DCM) is a heteroge- regulatory proteins, or ion channels [6]. neous heart disease with variable aetiological and clinical features. The disease is character- A recent genome wide association study (GWAS) ized by ventricular chamber enlargement and revealed that two polymorphisms, ADD2 systolic dysfunction that ultimately result in rs7597774 (adducin 2) and HSPB7 rs1739843 sudden cardiac death or progressive heart fail- (heat-shock 27 kDa protein family, member 7), ure with the eventual consequence of cardiac were associated with DCM in European popula- transplantation [1-4]. The pathophysiology of tions [7]. In a second GWAS, however, HSPB7 DCM is multifactorial with a possible implica- rs1739843 was not found to be associated tion of environmental factors and the existence with sporadic DCM in various western popula- of a strong genetic component as demonstrat- tions [8]. Furthermore, no relationship between ed by a high rate of familial aggregation [5]. To the HSPB7 single nucleotide polymorphisms date, approximately 33 genes have been identi- (SNPs) and genetic susceptibility to idiopathic Variant rs7597774 in ADD2 and dilated cardiomyopathy DCM was found in a small Chinese Han cohort Clinical characteristics [9]. An association between ADD2 rs7597774 and DCM, however, has not yet been examined The clinical data included age, gender, hyper- in a population of non-European ancestry. tension, type 2 diabetes mellitus (T2DM), and left ventricular ejection fraction (LVEF), left ven- To further investigate the role of rs7597774 tricular end-diastolic diameter (LVEDD), and left and rs1739843 in DCM, allelic and genotypic atrial diameter (LAD) of echocardiographic association analyses were performed on DNA parameters in both groups. New York Heart samples from an independent case-control Association (NYHA) heart functional classifica- DCM cohort with a total of 1783 Chinese Han tion, therapeutic regimens, and serum brain subjects from central and northeastern China. natriuretic peptide (BNP) concentrations were Specific clinical features of DCM patients were also obtained from medical records for DCM also included in the analyses in order to poten- patients. Hypertension was defined as systolic tially reveal associations with the functional blood pressure ≥ 140 mmHg or diastolic blood consequences of the disease and to provide a pressure ≥ 90 mmHg. The criteria set by the molecular basis for the selection of treatment American Diabetes Association was applied for options. a diagnosis of T2DM [11]. Serum BNP levels were determined using a high-sensitivity Materials and methods enzyme-linked immunosorbent assay kit (R & D Systems; Minneapolis, MN, USA). Ethics statement SNP genotyping All protocols performed in this study were approved by the Ethics Committee of First Genomic DNA was isolated from peripheral Affiliated Hospital of Dalian Medical University blood lymphocytes with the TIANamp Blood and Huazhong University of Science and Tech- DNA Kit (TiangenBiotect; Beijing, China) accord- nology. Written informed consent was obtained ing to the manufacturer’s protocols. PCR was from all subjects participating in the study. The performed in a 25 μL final volume containing study conformed to the principles outlined in 1.5 mM Mg2+, 0.2 mM dNTPs, 0.5 μM each the Declaration of Helsinki. primer (rs1739843: forward, 5’-ACC CGC ATC Study subjects CGC CCC CCT ATA G-3’, reverse, 5’-GGG GGT GGG GCT TGA GGG TG-3’; rs7597774: forward, All subjects were selected from GeneID, which 5’-AGC CCT GTC CAG CCC TGA G-3’, reverse, is an ongoing Chinese population database. 5’-TTG GGC ACT GAG GCA CCT G-3’), 25 ng of DNA samples and clinical information are col- human genomic DNA template, 5 μM SYTO9 lected from individuals with cardiovascular and green fluorescent intercalating agent, and 0.15 cerebrovascular diseases national wide in an U of Taq DNA polymerase. PCR was performed effort to identify susceptibility loci related to on an ABI 9700 System (Life Technologies; these diseases [10]. Grand Island, NY, USA) with the following ther- mal profile: 95°C for 5 min; 40 cycles of 95°C The study subjects were from central and north- for 10 s, corresponding annealing temperature eastern China and were ethnic Chinese Han by (57.4°C for rs1739843, 60.3°C for rs7597774) self-description. The criteria for a diagnosis of for 10 s, and 72°C for 15 s; and a final cycle of DCM were in accordance with the guidelines 72°C for 10 min. PCR amplicons were directly established by the America Heart Association genotyped using high-resolution melting analy- in 2006. Patients with known causes such as sis (HRM) on the Rotor-Gene 6000 System acute viral myocarditis, coronary artery dis- (Corbett Life Science, Australia) under standard ease, valvular disease, congenital heart defects protocols with minor modifications [12]. During and a positive family history of DCM were each run of HRM, three positive control DNA excluded. The controls were individuals without samples with known genotypes (TT, CT, and CC DCM as determined by echocardiography or for rs1739843; and AA, AC, and CC for medical history at the time of enrollment, and rs7597774), as well as a negative control with- who underwent annual physical exams with/ out DNA template were included. To validate without any diseases. the accuracy of HRM genotyping data, ten sam- 1189 Int J Clin Exp Med 2015;8(1):1188-1196 Variant rs7597774 in ADD2 and dilated cardiomyopathy Table 1. Baseline clinical characteristics of study groups responding 95% confidential intervals (95% CI) were also Characteristics DCM Group Control Group P-value calculated. Genotypic asso- Number 399 1384 N/A ciation analysis under three Age (M ± SD, y) 55.97 ± 15.194 57.3 ± 16.074 0.67 genetic models (dominant, Gender (Male) 62.66% 56.79% 0.038 recessive, and additive) was Hypertension (1/0) 143/256 616/768 0.002 performed using 2 × 3 con- T2DM (1/0) 53/344 237/1149 0.076 tingency tables assessed by LVEDD (M ± SD, mm) Pearson’s chi-squared (χ2) Male 65.00 ± 9.329 44.49 ± 4.196 < 0.001 test. Multiple logistic regres- Female 60.70 ± 7.523 42.04 ± 4.481 < 0.001 sion analysis was used to LVEF (M ± SD, %) 35.88 ± 11.98 59.62 ± 6.358 < 0.001 adjust covariates such as BNP levels (M ± SD, pg/ml) 1022.55 ± 910.86 N/A - sex, age, hypertension, T2D- LAD (M ± SD, mm) M. When the case-control Male 44.08 ± 6.529 33.00 ± 5.144 < 0.001 samples were divided into Female 40.69 ± 9.160 31.84 ± 6.597 < 0.001 several subgroups, basic sta- M ± SD, mean ± standard deviation; T2DM, type 2 diabetes mellitus; LVEDD, left tistical methods were applied ventricular end-diastolic diameter; LAD, left atrial diameter; BNP, brain natriuretic as described. peptide; N/A, data not available. For the association between age, LVEF, LVEDD, LAD, BNP ples for each genotype of both SNPs were ran- levels and rs7597774, One-Way analysis of domly selected for Sanger sequencing. Primers variance (ANOVA) was used. For the association for sequencing the SNPs were the following: between rs7597774 and NYHA heart functional rs1739843: forward, 5’-TCC CCA CCT ACC CGC classification or therapeutic regimens, a non- ATC C-3’ and reverse, 5’-GCC CCC TCA CTG CCT parametric test, Ridit analysis and the Kruskal- CTC TT-3’ for; rs7597774: forward, 5’-CGG CCT Wallis H test, were used, respectively.