| Coronary artery disease (CAD) is one of the leading causes of death worldwide. It is a complex disease resulted from numerous gene-gene and gene-environment interactions. It is commonly accepted that dyslipidemia, including elevated levels of atherogenic lipoproteins and/or reduced levels of high-density lipoprotein (HDL), is a prerequisite for most forms of CAD. Moreover, epidemiological studies over the past 50 years have revealed that multiple genes, especially those involved in lipid metabolism, are responsible for the genetic susceptibility of CAD.Cholesterol 7a-hydroxylase (CYP7A1), which catalyzes the initial catabolic reaction of cholesterol and serves as the rate-limiting factor of regulation of bile acid synthesis in the liver. Therefore, CYP7A1 is thought to be one of the candidate genes associated with dyslipidemia and CAD, as wellas a putative new target for gene therapy to prevent CAD.In the post-genomic era, study on association of sequence variation with phenotype is one of the main objectives of medical genetics. Single nucleotide polymorphisms (SNPs), the third- generation genetic marker, possess the characteristics of large numbers and dispersed distribution. SNPs, especially those in the coding regions (cSNPs) and gene regulatory elements are implicated as a causative factor in human genetic disease. Association study based on population level may find the possible SNP and/or haplotype associated with the disease. They are of importance for clarifying the genetic pathology of some polygenic inheritance disease.To further our understanding of the possible role played by SNPs of the CYP7A1 gene in dyslipidemia and CAD, we examined the distribution of a known SNP (A-204C) of CYP7A1 gene in 183 Chinese patients with CAD and 181 controls in Chengdu area by PCR-RFLP. Then, we screened the unknown SNPs of this gene by high-throughput denaturing high-performance liquid chromatography (DHPLC), and further confirmed by DNA sequencing and RFLP assay. Finally, we analyzed the association of these SNPs with lipid metabolism in patients with CAD.As to the known SNP-A-204C, CYP7A1 gene allele frequencies of C, A were 84% and 16% in CAD group and 82.2% and 17.8% in control group, respectively. There was no significantdifference in frequencies of alleles and genotypes between CAD group and control group (P>0. 05). However, in CAD patients there was significant difference in total cholesterol (TC) levels between CC, CA and AA genotypes (P<0. 05), and the levels of high density lipoprotein cholesterol (HDL) and low density lipoprotein cholesterol (LDL) in CAD patients with AA genotype were lower than those in CAD patients with CC and CA genotypes (P <0.05). In addition, in control group there was significant difference in TC levels between CC and CA genotypes (P <0.05). The frequencies of C, A alleles at A-204C polymorphic site were significantly different from those reported in Caucasian (PA in intron 2 of the CYP7A1 gene was discovered by using DHPLC, DNA sequencing and RFLP analysis. The allele frequencies of G and A were 60.4% and 39.6% in CAD group and 62.4% and 37.6% in control group, respectively. There was no significant difference in frequencies of alleles and genotypes in this polymorphism between the CAD group and the control group (P>0.05). However, the LDL and VLDL levels of AA genotype were significantly different fromthat of GAgenotype in the female subgroup of CAD patients(P<0.05). Therefore, the 20890A polymorphism may be related to LDL and VLDL levels in the plasma and contribute to dyslipidemia and CAD in Chinese in Chengdu area.Additionally, three other new SNPs were observed. They are 5656OA at the end of exon 4, a synonymous mutation of 7653OT (S253S) in exon 5 and 87... |
PDF Full Text Request