Summary: | <sec><title>Background:</title><p>Evidences suggest that paraoxonase 1 (PON1) confers important antioxidant and anti-inflammatory properties when associated with high-density lipoprotein (HDL).</p></sec><sec><title>Objective:</title><p>To investigate the relationships between p.Q192R SNP of <italic>PON1</italic>, biochemical parameters and carotid atherosclerosis in an asymptomatic, normolipidemic Brazilian population sample.</p></sec><sec><title>Methods:</title><p>We studied 584 volunteers (females n = 326, males n = 258; 19-75 years of age). Total genomic DNA was extracted and SNP was detected in the TaqMan<sup>®</sup> SNP OpenArray<sup>®</sup> genotyping platform (Applied Biosystems, Foster City, CA). Plasma lipoproteins and apolipoproteins were determined and PON1 activity was measured using paraoxon as a substrate. High-resolution β-mode ultrasonography was used to measure cIMT and the presence of carotid atherosclerotic plaques in a subgroup of individuals (n = 317).</p></sec><sec><title>Results:</title><p>The presence of p.192Q was associated with a significant increase in PON1 activity (RR = 12.30 (11.38); RQ = 46.96 (22.35); QQ = 85.35 (24.83) μmol/min; p < 0.0001), HDL-C (RR= 45 (37); RQ = 62 (39); QQ = 69 (29) mg/dL; p < 0.001) and apo A-I (RR = 140.76 ± 36.39; RQ = 147.62 ± 36.92; QQ = 147.49 ± 36.65 mg/dL; p = 0.019). Stepwise regression analysis revealed that heterozygous and p.192Q carriers influenced by 58% PON1 activity towards paraoxon. The univariate linear regression analysis demonstrated that p.Q192R SNP was not associated with mean cIMT; as a result, in the multiple regression analysis, no variables were selected with 5% significance. In logistic regression analysis, the studied parameters were not associated with the presence of carotid plaques.</p></sec><sec><title>Conclusion:</title><p>In low-risk individuals, the presence of the p.192Q variant of <italic>PON1</italic> is associated with a beneficial plasma lipid profile but not with carotid atherosclerosis.</p></sec>
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