Association between M/L55-polymorphism of paraoxonase enzyme and oxidativeDNA damage in patients with type 2 diabetes mellitus and in control subjects

The paraoxonase enzyme (PON) gene polymorphism causes a change of methionin e (M-allele) to leucine (L-allele). PON may reduce low density lipoprotein oxidation and prevent atherosclerosis. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) is a sensitive index of oxidative DNA damage. We have studied the association between the PON genotypes and the urinary excretion of 8-OHdG. The study population consisted of 93 Finnish type 2 diabetes patients and 1 06 non-diabetic control subjects. The 24-h excretion of 8-OHdG was signific antly higher in diabetic patients than in control subjects (P < 0.001). In control subjects, the ratio of the 8-OHdG/glomerular filtration rate increa sed in order of genotype from MM to ML to LL (P < 0.0412). These results su ggest that lipid peroxidation may have an effect on DNA oxidation.