Association of COL4A1 genetic polymorphisms with coronary artery disease in Uygur population in Xinjiang, China

Dilare Adi 0 1 Xiang Xie 0 1 Yi-Tong Ma 0 1 Zhen-Yan Fu 0 1 Yi-Ning Yang 0 1 Xiao-Mei Li 0 1 Yang Xiang 0 1 Fen Liu 0 Bang-Dang Chen 0 0 Xinjiang Key Laboratory of Cardiovascular Disease Research , Urumqi 830054 , People's Republic of China 1 Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University , Urumqi 830054 , People's Republic of China Background: Type IV collagen is important for the structural integrity and function of basement membranes. Basement membranes surround vascular smooth muscle cells in the media, COL4A1 is the most abundant component of type IV collagen in all Basement membranes. However, the relationship between COL4A1 genetic polymorphisms and coronary artery disease (CAD) remains unclear. We performed a case-control study to explore the association of COL4A1 genetic polymorphisms with CAD in Uygur population of China. Methods: 1095 Uygur people (727 men, 368 women) including 471 CAD patients and 624 controls were selected for the present study. Two SNPs (rs605143 and rs565470) were genotyped by using the polymerase chain reaction-restriction fragment length (PCR-RFLP) method. Results: For total and men, the rs605143 was found to be associated with CAD by in a dominate model (p = 0.014, p = 0.013, respectively). The difference remained statistically significant after multivariate adjustment (p = 0.036, p = 0.014, respectively). The rs565470 was also found to be associated with CAD in a recessive model for total and men (both p < 0.001), and the difference remained statistically significant after multivariate adjustment (P = 0.002, P = 0.001, respectively). Conclusion: Both rs605143 and rs565470 of COL4A1gene are associated with CAD in Uygur population of China. - Introduction Coronary artery disease (CAD) is the leading cause of death worldwide, which is caused by multiple interacting endogenous and exogenous factors. In recent years, genetic basis of CAD has gained considerable interest [1]; heritable factors accounted for 40%-60% in occurrence and development of CAD [2]. Genome- wide association studies (GWAS) some large-scale association analysis have identified many common, uncommon and functional variants for CAD [3,4]. Collagens are a group of proteins characterized by a unique sequence whose every third amino acid is a glycine (Gly-Xaa-Yaa motif ). There are at least 25 different types of collagens. The most abundant four found in mammals are Type I, II, III and IV collagens [5]. Among them, Type IV collagen is the main component comprising 50% of all basement membrane (BM) and is expressed at all tissues including the vasculature, renal glomerular and ocular structures [6,7]. The vascular BM is an important component of the vasculature. BM surrounds vascular smooth muscle cells in the media making up the barrel of every blood vessel and capillary [8]. As is known, integrity and stability of blood vessels are critical to vascular system, and maintenance of vessel system can be successfully achieved by cooperation of many constituents of blood vessels such as endothelial cells, pericytes, and BM. However failure of this system results in serious consequences such as hemorrhage, edema, inflammation, and tissue ischemia. Type IV collagen, a major component of vascular BM, could provide physical barrier to both soluble molecules and migrating cells and could function as scaffold that allows interaction between pericytes and endothelial cells, thereby contributing to vessel stabilization and enables BM to with-stand mechanical stress [9]. COL4A1 gene is mapped on the telomeric region of 13q (13q34) and consists of 52 exons encodes a1 chain of type IV collagen [10]. In recent years, understanding of polymorphisms of the COL4A1 gene reached a certain degree. For example, Yamada Y et al. [11] identified a novel polymorphism in the COLA1 which is significantly associated with prevalence of myocardial infarction. A Genome-Wide Association Scan (GWAS ) study conducted by Kirill V et al. reported that COL4A1 gene is associated with arterial stiffness [12]. However, the relationship between polymorphisms of COL4A1 gene and CAD remains unclear. In the present study, we aimed to clarify the association of COL4A1 gene polymorphisms with CAD in a Uygur population of China. Methods Ethical approval of the study protocol This study was approved by the Ethics Committee of the First Affiliated Hospital of Xinjiang Medical University (Xinjiang, China). It was conducted according to the standards of the Declaration of Helsinki. Each participant gave written informed consent and explicitly provided permission for DNA analyses as well as collection of relevant clinical data. Study population Study population is comprised of 1095 Uygur people (726 men, 368 women) who lived in Xinjiang Uygur Autonomous Region of China. Among them, 471 subjects attended as inpatients at the First Affiliated Hospital of Xinjiang Medical University between January 2006 to 2011 and underwent coronary angiography, diagnosed with CAD (based on the presence of at least one significant coronary artery stenosis of > 50% luminal diameter). Data and information about traditional coronary risk factors (including hypertension, diabetes mellitus, and smoking) and other biochemical indices were collected from all participants. The diagnosis of hypertension was established if patients were on anti-hypertensive medication or if the mean of 3 measurements of systolic blood pressure (SBP) 140 mmHg and/or diastolic blood pressure (DBP) 90 mmHg. Diabetes mellitus was defined on the basis of the World Health Organization (WHO) criteria. Smoking was classified as smokers (including current or ex-smokers) or non smokers. Patients with congenital heart disease, multiple organ failure syndrome and drug users were excluded from this study. The control subjects were comprised of 624 subjects selected from the Cardiovascular Risk Survey (CRS) [13,14]. This Survey consists of 14,618 subjects and is a multipleethnic, community-based, cross-sectional study designed to investigate the prevalence, incidence, and risk factors for cardiovascular diseases in Han, Uygur, and Kazakh population in Xinjiang (west China) between June 2007 and March 2010. Individuals who had underwent heart bypass surgery, coronary stenting, had history of myocardial infarction, CAD, electrocardiographic signs of CAD, and relevant valvular abnormalities in echocardiograms were excluded from this group. Biochemical analyses 5 mL of fasting venous blood was collected into tubes containing ethylene diamine tetraacetic acid (EDTA). The collected samples were centrifugated into plasma, serum and blood cells (including leukocytes). Genomic DNA was extracted from the peripheral leukocytes using standard phenol-chloroform method and stored at 80C for future analysis. We used standard methods for chemical analysis (Dimension AR/AVL Clinical Chemistry System, Newark, NJ, USA) employed by the Clinical Laboratory (...truncated)