New data on the world distribution of paraoxonase (PON1 Gln 192 - Arg) gene frequencies.

Human paraoxonase (PON), a serum enzyme that hydrolyses organophosphate insecticides and nerve agents, plays an unclear physiological role. Of the three genes in the paraoxonase gene family, PON1 shows a polymorphism, Gln 192- Arg, governed by two common alleles, named *Q and *R. These determine two different isoforms associated respectively with lower and higher activity towards paraoxon, a toxic metabolic product of the insecticide parathion. The *R allele has been often found associated with increased risk of coronary heart disease. As human populations go towards greater exposure to environmental changes, including changes in dietary habits, contact with insecticides or other toxic substances, health risks will change as well. In the prevention of these newly emerging risks, it could be important to know the distribution of the two alleles in the various world populations. In this paper we report on the genotype and allele frequencies in different populations, most of whom have never been examined for this polymorphism. Samples were taken from mainland Italy, Sardinia, Ethiopia, Benin, and Ecuador. The *R allele frequencies for the samples were: 0.313, 0.248, 0.408, 0.612, and 0.789, respectively. The data show a large variability in the allele frequencies, and in particular that the PON1 allele distribution depends on membership to different geographic populations.