Determination of Serum Paraoxonase (PON1) Phenotype Distribution

Serum paraoxonase (PON1) is a high-density lipoprotein (HDL)-associated esterase that can prevent the formation of oxidized low-density lipoprotein (ox-LDL). PON1 activity is reduced in cardiovascular diseases. In the present study, distribution of PON1 phenotypes in patients with coronary artery disease (CAD) was determined. Also, as studies on the association between PON1 activity and the extent of coronary stenosis are limited, the relationship between paraoxonase and arylesterase activities of PON1 with extent of coronary stenosis has been investigated. Sixty one patients with coronary stenosis of <50% and sixty three patients with coronary stenosis of >70% were included in this study. Paraoxonase and arylesterase activities were measured using paraoxon and phenylacetate as substrates, respectively. Phenotyping of the PON1 Q192R polymorphism was determined by double-substrate method. In patients with stenosis of <50%, 41%, 46% and 13% of the patients belonged to phenotypes of Q, QR and R, respectively. The corresponding values in patients with stenosis of >70% were 48%, 41% and 11%, respectively. Patients with stenosis of <50% had significantly higher paraoxonase and arylesterase activities (P= 0.02 and P = 0.04, respectively) compared to those with stenosis of >70%. The levels of HDL-C in patients with stenosis of <50% were significantly higher than those of >70% stenosis group (P=0.025). In the present study, phenotype distribution of PON1 in subjects with CAD was determined. Also, there were significant differences in paraoxonase and arylesterase activities and also HDL-C levels between patients with coronary stenosis of <50% and those with coronary stenosis of >70%. Therefore, this study provides further support for the important role of paraoxonase activity in coronary atherosclerosis.