Abstract: Objective　To investigate the distribution characteristics of the I474V loci of proprotein convertase subtilisin lkexin type 9 (PCSK9) gene in coronary artery disease (CAD) patients and healthy subjects, study the correlation of blood lipid levels， the development of CAD and the severity of coronary lesions，and provide the reference to elucidate the pathogenesis and genetic risk assessment of CAD.   Methods　According to the results of coronary angiography, blood samples from 288 CAD patients and 300 healthy controls were collected. I474V polymorphism loci in PCSK9 gene was detected by bi-directional polymerase chain reaction (PCR) amplification of specific alleles (Bi-PASA PCR). The results were further confirmed by cycle sequencing. Serum levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were measured by enzymatic methods. Results　Ⅱ and Ⅳ genotypes were dominant in the I474V polymorphism loci of PCSK9 gene. No significant difference was found in allele frequencies of I474V loci between CAD patients and healthy controls (P>0.05). There was statistical significance in TC, LDL-C and HDL-C levels between CAD patients and healthy controls (P<0.05), and the TG level had no statistical significance (P>0.05). Serum levels of TC and TG (P<0.05), but not HDL-C and LDL-C (P>0.05) were statistically different between Ⅱ and Ⅳ genotypes in CAD patients. Subjects with I474V polymorphism of PCSK9 gene had significantly higher serum levels of TC and TG than subjects without I474V polymorphism. The number of coronary lesions was more in patients with Ⅳ genotype than Ⅱ genotype with statistical difference (P<0.05). Conclusions　Ⅱ and Ⅳ genotypes are dominant in the I474V polymorphism loci of PCSK9 gene. The genotype of PCSK9 gene I474V polymorphism is correlated with serum increasing levels of TC and TG and the severity of coronary lesions in CAD patients.

Key words: Proprotein convertase subtilisin lkexin type 9, I474V polymorphism, gene, Coronary artery disease