Study On The Correlation Between Single Nucleotide Polymorphisms Of SRB1 And ITGB2 Gene And Coronary Heart Disease

BackgroundCoronary heart disease (CHD) is caused by the interaction of genetic and enviromental factors. CHD is one of the leading cause of death and disability worldwide. Lipid metabolism and inflammation are two mechanism of the development of CHD. Scavenger receptor class B, type Ⅰ (SRB1) is a key regulator of high density lipoprotein (HDL) metabolism. It facilitates the efflux of cholesterol from cells in peripheral tissues to HDL and mediates the selective uptake of cholesteryl esters from HDL in the liver. SRBI deficiency is associated with down-regulation of cholesterol homeostasis in the arterial wall that results in an increased susceptibility to atherosclerosis. Inflammation is another mechanism of atherosclerotic disease.Leukocyte adhesion and chemotaxis is the first step of inflammation. And the basis of cell adhesion is adhesion molecules. Integrin beta 2(ITGB2, integrin beta 2), namely CD18, is an important member of the integrin family of adhesion molecules. In our previous proteomics research, the expression of ITGB2 has differences between epicardial and subcutaneous adipose tissue from patients with and without CAD. Coronary heart disease is a complex polygenic hereditary disease, research of the genetic pathogenesis of CHD may provide a new methods for diagnostic of CHD.ObjectiveTo study the correlation between the polymorphism of SRB1 and ITGB2 gene and the onset of CHD, we analyzed differences of alleles and genotypes frequencies between CHD group and non-CHD group. And we also analyzed differences of the indexes related to metabolism among different genotypes of each SNPs.Methods1. ParticipantsOur participants are selected from the CHD research database of Peking union medical college hospital.The diagnostic criteria of CHD:according to the coronary angiography results, one or more branch of right or left main trunk, left anterior descending, left circumflex branch have a narrow of 50% or higher.We select patients with stenosis of 75% or more into CHD group,and coronary angiography results no abnormal or stenosis<25% into non-CHD group. The two groups are matched of gender, age, BMI, proportion of diabetes, proportion of dyslipidemia patients.2. Screening SNPs loci(1) Select gene tag SNPs in haploview, choose SNPs in promoter, exons,3’UTR or 5’ UTR, then find the MAF value (minimum allele frequency) of target SNPs in the Hapmap based on principles of MAF greater than 0.05;(2) Screening SNPs loci according to genome-wide association study (GWAS) results and literature reported. Select those has positive reported results or trends.3. SNP detection methodsUse OMEGA DNA extraction kit to extract DNA, Sequenom MassARRAY SNP detection platform to test. Detection process mainly includes primers design and synthesis, PCR amplification reaction, SAP, purification, single base extension, mass spectrometry analysis, test results using TYPER 4.0 software (sequenom).4. The statisticsUse Plink software to analyze the genotype frequency distribution of Hardy Weinberg equilibrium (HWE), minimum allele frequency (Minor allele frequency, MAF) and "case-control" correlation study.Use SPSS(Version 17.0) to analyze the measurement data comparison between different genotypes. If the P value is less than 0.05, it indicates a significant difference.Results1. Information of objective:496 cases in CHD group, including 256 men,244 women, average age was 60.19±9.8 years old.367 cases in non-CHD group, including 181 men, 186 women, average age was 59.39±11.0 years old. There are no significant differences between the two groups in gender, age, BMI, proportion of diabetes, proportion of dyslipidemia patients.2. Hardy-Weinberg Equilibrium:Tthe genotypes frequencies of all the six SNPs were consistent witll those expected under Hardy-Weinberg Equilibrium test.3. "Case-Control" association analysis:Between the CHD group and non-CHD group, there Was a significant difference in the alleles frequency(p=0.017),genotype frequency(p=0.0028), recessive model (p=0.000672) of rs838880.4. Comparing the measurement data in different genotypes of SNPs:Among three genotypes of rs5888, there was a significant difference(p=0.03)in the level of History of dyslipidemia and serum LPA. Among three genotypes of rs235236, there were significant differences in the levels of serum HDL、APOA1 and history of hypertension.Among three genotypes of rs2070947, there was a significant difference in the level of serum APOA1、hsCRP.ConclusionThere is a correlation between the rs838880 of SRB1 and the onset of CHD,and CC genotype could reduce the risk of CHD. There is a correlation between the rs838880 of SRB1 and the onset of CHD. Rs5888 of SRB1 has a correlation with dyslipidemia, AA genotype may have protective effect. CT genotype of rs2070946 may be a risk factor for inflammation.