Evaluation of Paraoxonase1 Polymorphisms in Hypothyroid Patients and Their Relationship with Paraoxonase Activity and Serum Lipids

Objective: The risk for atherosclerosis increases in hypothyroidism, although its associated mode of pathogenesis has not been determined yet. Paraoxonase1 (PON1) is an enzyme that is antioxidative and antiatherogenic. This study was planned to determine distributions of PON1 192 and 55 gene polymorphisms in hypothyroid patients and healthy individuals and to investigate the effects of these polymorphisms on PON1 activity and serum lipids. Material and Methods: Seventy-five primary hypothyroid patients and 45 healthy volunteers were recruited into the study and PON1 192 and 55 gene polymorphisms, serum PON1 activity, and lipid profiles were measured in them. Results: The activity of PON1 declined in the recruited patients compared to that in the control group (p<0.05). No significant difference was observed in PON1 192 Q/R and 55 L/M genotype distributions and allele frequencies between patients and the control group. Moreover, these polymorphisms affected PON1 activity (p<0.05) but had no effect on serum lipids. Conclusion: PON1 192 and 55 polymorphisms cause significant changes in paraoxonase activity. PON1 activity was lower in hypothyroid patients and was independent of these polymorphisms, thus does not create any genetic risk for increased atherosclerosis in these patients.