The status of the human serum paraoxonase in a Romanian sample

Written by Kaucsár Tamás, Dronca Eleonora, Paşca P. Sergiu, Nemeş Bogdan, Endreffy Emőke, Dronca Maria

Human serum paraoxonase (PON1) is a calcium-dependent hydrolase, associated with high density lipoprotein (HDL). PON1 is involved in the pathogenesis of cardiovascular diseases by protecting LDL against peroxidation. It also plays a major role in detoxifying neurotoxic organophosphorus compounds (such as paraoxon) and nerve agents. The PON1 gene has two common coding region polymorphisms: L55M and Q192R, leading to decreased serum PON1 levels and modifying the substrate affinity of the enzyme towards paraoxon. The goals of the present study were to examine the frequencies of the two PON1 genotypes in a sample from the general Romanian population and to verify whether the PON1 phenotype could predict the Q192R genotype. Therefore we have performed special genetic melting point analysis with real-time PCR technology and we assayed the paraoxonase and arylesterase activities of the PON1 enzyme using spectrophotometric methods in 79 individuals. The frequencies of the PON1 genotypes were: 56,96% QQ, 37,97% QR and 5,06% RR, respectively: 13,92% MM, 55,70% ML and 30,38% LL. Through the two-dimensional enzyme analysis plot we detected that the values fall along one of three distinct lines according to the PON1 Q192R genotypes. At the same time the ratio of the paraoxonase/arylesterase activity showed separation of all three PON1 192 genotypes, with no overlap between the groups (QQ: < 4, QR: 4-10, RR: > 10). Our study is the first to investigate the distribution of genotypes in the Romanian population. It also shows that the PON1 phenotype estimates the PON1 Q192R genotype, hence being more useful and informative than the genotype alone.

Print   Email