PON1 L55M polymorphism is not a predictor of coronary atherosclerosis either alone or in combination with Q192R polymorphism in an Italian population

Background: The present study evaluated the role of the PON1 L55M polymorphism independently and in conjunction with the Q192R polymorphism on the risk of coronary atherosclerosis in an Italian population. Materials and methods: Three hundred and ninety-one subjects with significant coronary stenosis (> 50%) (coronary artery disease-positive; CAD +), 196 subjects with normal coronary arteries (< 10% stenosis) (CAD -) and 178 healthy controls were screened using a combination of polymerase chain reaction and restriction enzyme digestion. Results: In the pooled population, the frequencies of L and M alleles were 0.63 and 0.37, respectively; the most common haplotypes were QQ/LM (24.2%) and QR/LL (21.8%) and a strong linkage disequilibrium between L/55 and R/192 alleles was observed (D′ = -0.91; P < 0.0001). CAD + subjects did not show any significant differences in the distribution of PON1-55 genotypes as compared to CAD - subjects and population controls (χ 2 = 1.5, P = 0.8). After controlling for other risk factors, the low-concentration M allele was not associated with a significant change of CAD risk (OR 1.02; 95% CI 0.80-1.29; P = 0.87). Moreover, the L55M polymorphism did not show any interaction with other risk factors such as smoking, diabetes, hypertension, low levels of high-density lipoprotein (HDL) or high ratios of low-density to high-density lipoproteins. The combination of L55M with the Q192R polymorphism did not show any effect on CAD risk. However, a marginal decrease in myocardial infarction risk was detected when QQ/MM carriers (OR 0.51; 95% CI 0.26-0.99; P = 0.048), but not LL/RR carriers, were compared with subjects not homozygous for an L or R allele. Conclusions: These findings did not indicate a major effect of the PON1 L55M polymorphism, either alone or in combination with the Q192R polymorphism, on CAD risk. Additional studies are needed for a better evaluation of the role of the 55/192 PON1 genotypes in combination on myocardial infarction risk.