SERUM PARAOXONASE ACTIVITY AND PON1 192 AND PON1 55 POLYMORPHISMS IN PREPUBERAL CHILDREN. THE FOUR PROVINCES STUDY

Background. Paraoxonase (PON1) is an ester hydrolase related to the elimination of oxidized compounds of low-density lipoprotein (LDL) particles and therefore to cardiovascular risk. The aim of the present study was to analyze the relationship between serum PON1 activity and PON1 192 and 55 polymorphisms in the prepuberal children included in the Four Provinces Study. Methods. The study population included 1,275 children aged 6 to 8 years old. Serum PON1 activity was measured by paraoxon hydrolysis. PON1 192Q/R and PON1 55M/L polymorphisms were analyzed by polymerase chain reaction and restriction analysis. Results. In the population as a whole, the prevalence of the less common PON192R allele was 30% and that of the PON55M allele was 38%, without significant differences in the frequencies between provinces. PON1 activity was highest in Orense and lowest in Murcia, both in the group as a whole and within each genotype. In Orense, significant correlations between PON1 activity and plasma total cholesterol, high-density lipoprotein cholesterol and apolipoprotein AI levels were found. Regression analysis showed that the PON1 192Q/R polymorphism is the main determinant of PON1 activity in our population. Conclusions. No significant differences between provinces in the frequencies of the PON192 and PON55 polymorphisms were found. However, although the PON192 polymorphism is the main determinant of PON1 activity, Orense showed the highest activity and Murcia the lowest for all the genotypes, suggesting that already at this age some factors are regulating PON1 activity for each genotype.