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 (chi2 = 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.     

Paraoxonase-1 (PON1) activity, but not PON1(Q192R) phenotype, is a predictor of coronary artery disease in a middle-aged Serbian population.

BACKGROUND: Paraoxonase-1 (PON1) is a high-density lipoprotein (HDL)-associated serum enzyme that protects lipoproteins from oxidative modifications. Polymorphisms in the gene, including PON1Q192R, have been studied. However, inconsistencies regarding the above-mentioned polymorphism obscure its association with vascular disease. METHODS: Using a two-substrate (paraoxon/diazoxon) activity method, we investigated the frequencies of PON1Q192R phenotypes in 261 middle-aged subjects: 156 patients with angiographically assessed coronary heart disease (CHD) and 105 CHD-free subjects as the control group. The PON1(192) phenotype was predicted from examination of the two-dimensional plot of hydrolysis rates of diazoxon vs. paraoxon and by using the antimode of the histogram of the ratio of diazoxonase/paraoxonase activity. RESULTS: The PON1Q192R phenotype frequencies in 113 patients with occlusion >50% (coronary artery disease-positive, CAD+ group) vs. control population were as follows: QQ (0.552 vs. 0.510), QR (0.382 vs. 0.408) and RR (0.066 vs. 0.082); chi2=0.414, p=0.813. We found lower paraoxonase (POase) and diazoxonase (DZOase) activities in the CAD+ patients when compared to the control population. According to logistic regression analysis, POase activity was a better predictor of coronary disease onset compared with DZOase activity measurements and PON1Q192R phenotyping. CONCLUSIONS: We conclude that enzyme activity (within a particular phenotypic group) is more important than phenotype alone in predicting susceptibility to coronary artery disease.     

郑州地区2型糖尿病肾功能衰竭患者芳香酯酶与基因Q192R多态性的关系

目的 探讨郑州地区汉族人群2型糖尿病慢性肾功能衰竭(DN-CRF)与血清芳香酯酶(ArE／PON1)活性及其192位基因多态性的关系。方法 通过检测2型糖尿病组(DM，121例)、DN-CRF组(123例)、健康对照组(127例)等观察对象的血清ArE／PONl活性及其192位基因多态性、血脂和脂蛋白等，进行分析研究。结果 郑州地区汉族人群中存在有ArE／PON1 192位等位基因Q与R，DN-CRF组Q、R基因频率为0．45和0．55，与DM、对照组比较，差异无统计学意义；两病例组患者血清酶活性均低于对照组，DN-CFR组降低幅度最大；DN-CFR组内RR基因型患者高密度脂蛋白胆固醇(HDL-C)、高密度脂蛋白2胆固醇(HDL2-C)水平低于QQ基因型，总胆固醇(TC)、甘油三酯(TG)和氧化型低密度脂蛋白(oxLDL)高于QQ基因型。结论 DN-CRF组ArE／PONl192位基因多态性与DM、健康对照组间虽差异无统计学意义，但不能排除DM合并DN-CRF与ArE／PON1的192位基因多态性有关；DN-CRF患者血清ArE／PON1活性降低，可能是DM合并DN的危险因素。     

Association between PON1 L/M55 polymorphism and plasma lipoproteins in two Canadian aboriginal populations.

Serum paraoxonase circulates on a subfraction of high density lipoproteins and appears to use phospholipids on both low and high density lipoprotein particles as a physiological substrate. This functional relationship could explain the reported associations between common variation in the PON1 gene--at codons 55 and 192--and phenotypes related to atherosclerosis and lipoprotein metabolism. We evaluated associations between plasma lipoproteins and PON1 L/M55, PON1 Q/R192 and PON2 A/G148 polymorphisms in samples from two Canadian aboriginal populations, namely the Oji-Cree and the Inuit. In diabetic Oji-Cree, we found that carriers of PON1 M55 had a higher mean plasma triglyceride concentration than non-carriers. In non-diabetic Oji-Cree, we found that carriers of PON1 M55 had higher mean plasma concentrations of total and low density lipoporetein cholesterol and apo B than non-carriers. In Inuit, we found that carriers of PON1 M55 had higher mean plasma concentrations of total and low density lipoprotein cholesterol than non-carriers. The other polymorphic markers were not associated with variation in any plasma lipoprotein trait. Thus, the PON1 M55 allele appeared to be associated with deleterious changes in the plasma lipoprotein profile from two independent Canadian aboriginal samples. These results suggest that common variation in PON1 codon 55 is associated with variation of intermediate traits in plasma lipoprotein metabolism in aboriginal Canadians.     

心肌梗死患者对氧磷酶-1 Q/R192基因多态性及活性检测的临床意义

目的探讨心肌梗死（AMI）患者对氧磷酶-1（PON1）Q/R192基因多态性及其活性检测的临床意义。方法分别采用紫外线分光光度法和聚合酶链式反应-限制性片段长度多态性（PCR-RELP）法检测65例AMI患者和70名健康体检者PON1活性及PON1Q/R192基因多态性。结果 AMI组血清PON1活性[（78.56±16.69）U/mL]明显低于健康对照组[（118.65±30.25）U/mL]（P〈0.01）。AMI组与健康对照组3种基因型及2种等位基因频率分布差异无统计学意义（P〉0.05）;AMI组与健康对照组间不同PON1 Q/R192基因型间血清PON1活性相比差异有统计学意义（P〈0.01）;AMI组内及健康对照组内PON1 Q/R192不同基因型间血清PON1活性相比差异无统计学意义（P〉0.05）。结论血清PON1活性降低是AMI的危险因素之一;PON1Q/R192基因多态性与AMI的发生无相关性。     

The paraoxonase-1 codon 192 polymorphism is associated with fasting total cholesterol and LDL-cholesterol concentrations only in postmenopausal women. The REGICOR study.

Paraoxonase-1 (PON1) is a high-density lipoprotein (HDL)-linked enzyme which appears to protect low-density lipoproteins (LDL) from oxidation. PON1 activity is associated with variation at the PON1 gene locus, specifically the common amino acid polymorphism at codon 192, for which the Q192 allele specifies low activity and the R192 allele specifies high activity. We investigated the association between the PON1 codon 192 polymorphism and fasting concentrations of glucose, lipids, lipoproteins and PON1 activity in 1380 subjects (724 men and 656 women). Several anthropometric and environmental factors were assessed in the present study. The PON1 Q192 allele frequency was 0.70 and 0.68 in men and women, respectively. In women, but not in men, significant associations were found between the PON1 codon 192 genotype and both total and LDL-cholesterol (p=0.004 and p=0.008, respectively), and subgroup analysis indicated that this relationship was predominant in postmenopausal women. Specifically, the Q192 allele was associated with increased total and LDL-cholesterol concentrations. Furthermore, these lipoprotein variables were higher among postmenopausal women with Q192/Q192 and Q192/R192 genotypes than in premenopausal women with the same genotypes (p<0.001). The findings suggest a gender-specific lipoprotein-genotype association with PON1 codon 192 genotypes in this study sample.     

Paraoxonase-1 gene in patients with chronic obstructive pulmonary disease investigation Q192R and L55M polymorphisms

BACKGROUND: The effect of increased oxidative stress on the development of chronic obstructive pulmonary disease(COPD) is well known. One of the antioxidative systems against oxidative stress in human body is paraoxonase(PON) enzyme that protects low density lipoproteins(LDL) against oxidation. This study aimed to explore the polymorphisms on PON1, Q192 R, L55 M genes of patients with COPD.METHODS: DNAs extraction was obtained from blood samples of 50 patients diagnosed with COPD and 50 patients as a control group who were presented to emergency clinic. Genotypes were obtained with polymerase chain reaction(PCR) and AIw I and Hsp92 II restriction enzymes were used for Q192 R and L55 M polymorphisms, respectively. Analysis of data was done with the Chi-square test and Fisher's exact test.RESULTS: A statistically significant difference in Q192 R polymorphism was found between the COPD patients and the control group(P=0.05). There was no statistically significant difference in L55 M polymorphisms between the patient and control groups(P0.05). Q192 R polymorphism was significantly correlated with the PON1 gene and cigarette smoking; however other risk factors did not show any significant correlation with this polymorphism. Though L55 M polymorphism was significantly correlated with family history and tuberculosis, there was no significant correlation with other risk factors.CONCLUSION: We believe that more studies are needed to study the correlation of L55 M polymorphism with other factors.     

Polymorphisms of pon1 and pon2 genes in hemodialyzed patients

Objectives

Q192R, L55M and -108C>T polymorphisms of pon1 gene affect PON1 paraoxonase activity while S311C polymorphism of pon2 gene might be associated with coronary heart disease. The aims of this study were to determine the frequencies of Q192R, L55M, -108C>T and S311C polymorphisms in hemodialyzed patients and to examine the relationship between pon1 gene polymorphisms and PON1 paraoxonase activity in those patients.

Design and Methods

The study included 238 control subjects and 263 hemodialyzed patients.

Results

PON1 paraoxonase activity was lower in patients. Genotype frequencies were different between two compared groups only for L55M polymorphism, with control group having higher frequency of MM genotype. Polymorphisms of pon1 gene were associated with significant variation in PON1 paraoxonase activity in both study groups.

Conclusion

Our results suggest that Q192R, L55M and -108C>T polymorphisms are not by itself the causal factors leading to the lower PON1 paraoxonase activity in hemodialyzed patients.     

Low paraoxonase activity in type II diabetes mellitus complicated by retinopathy

Human serum paraoxonase 1 (PON1) is located on high-density lipoprotein and has been implicated in the detoxification of organophosphates, and possibly in the prevention of lipid peroxidation of low-density lipoprotein. PON1 has two genetic polymorphisms, both due to amino acid substitutions: one involving glutamine (Q genotype) and arginine (R genotype) at position 192, and the other involving leucine (L genotype) and methionine (M genotype) at position 55. We investigated the effects of these polymorphisms, and of a polymorphism of the PON2 gene at position 310 (Cys/Ser; C and S genotypes respectively), on serum PON1 activity and concentration, plasma lipids and lipoproteins and glycaemic control in 93 individuals with type II diabetes with no complications and in 101 individuals with type II diabetes with retinopathy. Serum PON1 activity in the group with no complications [median 164.1 nmol.min(-1).ml(-1) (range 8.0-467.8)] was significantly higher than in the group with retinopathy [113.4 nmol. min(-1).ml(-1) (3.0-414.6)] (P<0.001), but the serum PON1 concentration was not different between the groups. The gene frequencies of the PON1-55 and PON1-192 polymorphisms and of the PON2-310 polymorphism were not different between the study populations. The PON1-55 and PON1-192 polymorphisms affected PON1 activity in the way described in a previous study of a control group and subjects with type II diabetes. The PON2-310 polymorphism also significantly affected serum PON1. PON1 activity was significantly higher in individuals with the PON2-310 CC genotype in both groups with type II diabetes, and the PON1 concentration was significantly higher in PON2-310 CC homozygotes with no complications than in the group with retinopathy. Neither the PON1-55 nor the PON1-192 polymorphism was correlated with the serum lipid or lipoprotein concentration in either group. In the group with retinopathy (but not the group with no complications), all three PON polymorphisms were correlated with glycaemic control, which was worse for the PON1-55 genotypes in the order MM>LM>LL (P=0.0032), for the PON1-192 genotypes in the order RR>QR>QQ (P=0.011) and for the PON2-310 genotypes in the order CC>CS>SS (P=0.010). Low serum PON1 activity in retinopathy may be related to an increased tendency for lipid peroxidation. Our findings thus raise the possibility that, in retinopathy, the PON2 gene may influence PON1, and that an inter-relationship between the PON1 and PON2 genes may influence glycaemic control in subjects with type II diabetes complicated by retinopathy.     

Hyperhomocysteinemia, paraoxonase activity and risk of coronary artery disease

OBJECTIVES: Paraoxonase-1 (PON1) detoxifies homocysteine thiolactone (HcyT) in human blood and could thus delay the development of atherosclerosis. We investigated (a) PON1 activity and polymorphisms, and (b) the relationship between PON1 activity, homocysteine (Hcy) and the severity of CAD patients in Tunisian population. DESIGN AND METHODS: We used PCR-RFLP analysis to detect the Q192R and L55M variants of the PON1 gene in 100 patients with CAD and in 120 healthy controls. Paraoxonase activity was measured spectrophotometrically using phenylacetate as a substrate. Total plasma homocysteine concentrations were determined by direct chemiluminescence assay. RESULTS: We found an increased Hcy level in CAD patients compared to the control group (15.86+/-8.63 vs. 11.9+/-3.25 micromol/L respectively, P<0.001), and a decrease in PON1 activity in CAD patients as compared to the control group (117+/-56 vs. 181+/-73 U/mL respectively, P<0.001). PON1 Q192R and L55M polymorphisms were not associated with the presence of CAD (P=0.592, P=0.294, respectively). However, we found that PON1 activity is lower with the PON1 192RR than with PON1 192QQ genotypes in the study population. Furthermore, there were no association between PON1 L55M polymorphism and PON1 activity. We showed a significant decrease in PON1 activity in CAD patients presenting 0- to 3-vessel stenosis (155+/-39; 135+/-36; 103+/-22; 77+/-24 U/mL, respectively; P<0.001). CONCLUSION: In this study, we showed that low PON1 activity is associated with the PON1 192RR genotypes and associated with the severity of CAD in the Tunisian population. We hypothesize that high level of Hcy together with low PON1 activity results in an increased plasma HcyT plasma concentration leading to protein N-homocysteinylation and the development and progression of atherosclerosis.     

The evaluation of two genetic polymorphisms of paraoxonase 1 in patients with pulmonary embolism

Background and Objective

Pulmonary embolism (PE) is caused by some genetic factors for more than half patients. Paraoxonase 1 (PON1) has significant anti‐oxidative and anti‐inflammatory effects. According to our knowledge, there is no study researching the relation between PON 1 gene polymorphisms and PE in the literature. Therefore, it is aimed to research possible impacts of PON 1 Q192R and L55M polymorphisms on PE, considering anti‐inflammatory and anti‐oxidative effects of PON 1 in Turkish population.

Methods

One hundred and five PE patients and one hundred and seventeen controls were enrolled in this study. Genomic DNA was isolated and genotyped using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analyses for the PON1 gene Q192R and L55M polymorphisms.

Results

Any associations were not found between clinical and demographical characteristics of PE patients and the PON1 gene Q192R polymorphism; however, there were associations between surgery, chronic renal failure, and cerebrovascular disease on the history of patients and L55M polymorphism (P = .013, P = .037, and P = .031, respectively). Genotype and allele frequencies did not show any significant differences between patients and controls according to PON1 gene Q192R and L55M polymorphisms (P > .05).

Conclusion

The results of this study suggest that there is no correlation between PE and PON 1 gene Q192R and L55M polymorphisms in the Turkish population from the Central Black Sea region. Besides, whole genotypes and alleles of Q192R and L55M are not risk factors for patients with PE in this population.

     

The paraoxonase L55M and Q192R gene polymorphisms and myocardial infarction in a Tunisian population

ObjectivesIn the present study, we examined a possible association between the PON1 Q192R and L55M polymorphisms and myocardial infarction (MI) in a sample of the Tunisian population.Design and methodsThree hundred and ten patients with MI and 375 controls were recruited. Paraoxonase gene polymorphisms at codon 192 and 55 were analyzed by PCR-RFLP.ResultsGenotype distributions and allele frequencies of L55M were similar among the control and MI groups. For the Q192R polymorphism patients with MI had significantly higher frequency of the RR genotype compared to controls [17.1% vs. 10.9%; OR (95% CI), 1.93 (1.24–3.02); p = 0.004]. The MI patient group showed a significantly higher frequency of the R allele compared to the controls [38% vs. 30%; χ² = 10.74, p = 0.001]. The association between the PON1 Q192R polymorphism and MI remained significant after adjustment for other well-established cardiovascular risk factors.ConclusionsThe present study showed a significant and independent association between the PON1 Q192R polymorphism (presence of R allele) and MI in the Tunisian population.     

Detecting the polymorphisms of paraoxonase (PON) cluster in Chinese Han population based on a rapid method

BACKGROUND: An increased risk of coronary heart disease has been shown to be associated with polymorphisms in PON1 gene in different populations. Polymorphisms in PON2 gene have been associated with the level of plasma lipoproteins and glucose and are thought to play a role in atherosclerosis. METHODS: To detect PONs polymorphisms more rapidly and reliably, we modified and improved the method established by Motti et al. We redesigned the primer for amplifying the common polymorphism at position 311 of PON2, which produced more reliable and efficient amplification. RESULTS: A second common polymorphism at codon 148 was also detected by our new method, as were the 2 polymorphisms in the PON1 gene. The new method allowed identification of 4 polymorphisms (PON1-192, PON1-55, PON2-148 and PON2-311) simultaneously. The PONs genotypes of 82 healthy persons were identified by this method. The allelic frequencies were: PON1-192: Q 46.3%, R 53.7%; PON1-55: L 95.1%, M 4.9%; PON2-148: A 85.4%, G 14.6%; PON2-311: S 77.4%, and C 22.6%, respectively. CONCLUSION: This method represents a simple, economical and time-saving technique to simultaneously detect 4 polymorphisms in the PON cluster. It provides a useful application to enable further study of the relationship between PON1 and PON2 and their role in atherosclerosis.     

HDL3-related decreased serum paraoxonase (PON) activity in uremic patients: comparison with the PON1 allele polymorphism

BACKGROUND: Patients with chronic renal failure on maintenance haemodialysis (HD) are at high risk of atherothrombotic events; an enhanced oxidant stress might have a major role. The decrease of human paraoxonase (PON1), an anti-oxidant high-density lipoprotein (HDL)-linked enzyme, is a possible mechanism for developing cardiovascular disease. To ascertain the causes of low PON1 in such patients, we investigated the contribution of both PON1 gene polymorphism and individual pattern of HDL. METHODS: On 74 HD patients (47 M and 27 F) and on 92 healthy individuals (HS, 48 M and 44 F), we studied PON1 activity, PON1 genotype (55 and 192 PON1 allelic polymorphisms) and the lipid profile, including the HDL subfractions. RESULTS: We observed in HD patients the following significant differences: (1) decreased median PON1 activity (73.5 vs. 110 U/l); (2) decreased mean HDL concentration (1.05 +/- 0.18 vs. 1.55 +/- 0.41 mmol/l); (3) decreased mean HDL3 concentration (0.79 +/- 0.21 vs. 1.28 +/- 0.24 mmol/l). Total HDL retained about 70% of serum activity, almost completely carried (95%) by the HDL3. Finally, PON1 activity remained significantly low in HD vs. HS after matching for the allelic polymorphism. CONCLUSIONS: The reduction of the HDL3, not the genetic PON1 polymorphism, seems the most important determinant of PON1 activity reduction in HD.     

The paraoxonase promoter polymorphism (-107)T>C is not associated with carotid intima-media thickness in Sicilian hypercholesterolemic patients

BACKGROUND AND OBJECTIVES: Increased plasma low-density lipoprotein-cholesterol (LDL-C) levels in hypercholesterolemic subjects are associated with enhanced LDL oxidation that represents an additional risk for atherosclerotic disease. Human serum paraoxonase (PON1), a high-density lipoprotein (HDL) associated enzyme, has been shown to protect LDL from oxidation, thus playing an important role in reducing the risk of atherosclerosis. PON1 gene polymorphisms have been found to be associated with the variations in serum PON1 levels and activities, and with the risk for coronary artery disease (CAD). This study was performed to evaluate the contribution of the PON1 promoter (-107)T>C and the coding region Gln 192 Arg (Q192R) and Leu 55 Met (L55M) polymorphisms to the presence of carotid atherosclerosis in 208 Sicilian subjects with primary hypercholesterolemia. METHODS: Carotid artery intima-media wall thickness (IMT) was measured as an indicator of early atherosclerotic disease. The subjects were classified according to whether they have a normal (1 mm) IMT. Subjects were also investigated for physical and biochemical parameters, including PON1 activity. RESULTS: No significant differences were detected among the PON1 genotypes with respect to age, sex, BMI, plasma lipids, systolic blood pressure in both groups of patients. There were significant differences between PON1 genotypes with respect to PON1 activity. The 192QQ, 55MM and (-107)TT genotypes showed lower PON1 activity compared to the RR, LL and CC genotypes. The PON1 (-107)T>C genotype distribution in both IMT groups showed no significant differences in percentage of TT, CT and CC genotypes. Similar results were obtained analyzing the Q192R and L55M genotype frequencies. Stepwise forward logistic regression analysis confirmed the lack of association between PON1 genotypes and carotid abnormalities. CONCLUSIONS: In conclusion, our data provided no evidence of a significant association between either PON1 promoter (-107)T>C or coding region, Q192R and L55M, polymorphisms and early carotid atherosclerosis in Sicilian hypercholesterolemic subjects.     

Variation at the paraoxonase gene locus contributes to carotid arterial wall thickness in subjects with familial hypercholesterolemia

OBJECTIVES: Paraoxonase (PON1) is a potent enzyme, physically associated with the high-density lipoprotein particle. PON1 may protect against cardiovascular disease (CVD), since it is capable of hydrolyzing oxidized LDL-cholesterol, thereby negating the detrimental effects of this lipoprotein on the arterial wall. DESIGN AND METHODS: In 187 patients with familial hypercholesterolemia, we studied the seven most common single nucleotide polymorphisms (SNPs) in both the coding and promoter sequences of PON1 (L55M, Q192R, T-107C, C-126G, G-162A, G-824A, and C-907G) in terms of PON1 activity and intima media thickness (IMT) of the carotid arterial wall, a validated surrogate marker for CVD. RESULTS: In concordance with several previous studies, we observed that the L55M, T-107C, G-162A, G-824A, and C-907G SNPs conferred PON1 activity towards phenylacetate, while this was not the case for the Q192R and C-126G SNPs. Importantly, in a multivariate regression analysis, G-824A proved to be an independent predictor of carotid IMT. Additionally, the two fully discordant homozygous haplotypes, C-907/G-824/G-162/C-126/T-107/55M versus -907G/-824A/-162A/-126G/-107C/L55, differed by 22% in carotid IMT (P = 0.007). CONCLUSIONS: Genetic variation at the PON1 locus has a strong influence on PON1 activity as well as on carotid IMT. These data indicate that PON1 is indeed involved in the pathogenesis of atherosclerosis. Whether this also translates into a role for PON1 in the occurrence of CVD events needs to be confirmed by large prospective studies in the general population.     

Are PON1 Q/R 192 and M/L 55 polymorphisms risk factors for diabetes complications in Turkish population?

ObjectivesWe investigated whether the human serum paraoxonase (PON1) Q/R 192 and M/L 55 polymorphisms are associated with the complications of the type 2 diabetes (T2D).Design and methodsStudy group was consisted of 50 healthy subjects and 100 type 2 diabetes mellitus (DM) patients. Following measuring of serum PON1 activity, isolation of DNA and genotyping analyses were performed.ResultsPON1 activity of the patients with complications was significantly reduced by 23.5% compared to the group of diabetic patients and by 26.3% than the controls. According to multivariate analysis, we observed a three times significant effect of Q/R 192 polymorphism on the susceptibility to the occurrence of complications.ConclusionsProtective effects of paraoxonase against peroxidation of LDL particles are important in T2D complications. Although both of the two polymorphisms are associated, 192 polymorphism seems to be stronger predictor of the risk of diabetic complications.     

Paraoxonase 1-192Q allele is a risk factor for idiopathic chronic pancreatitis.

BACKGROUND: The cause of chronic pancreatitis (CP) remains unknown. However, oxidative stress might play a role since recent animal studies have demonstrated that oxygen-free radicals contribute to the pathogenesis of experimental pancreatitis. Human serum paraoxonase (PON1) is an antioxidant enzyme that protects against cellular damage from oxidative stress. Genetic variations resulting in variable activity rates of this enzyme, are of toxicological and physiological importance. AIM: We investigated whether genetic polymorphisms of the PON1 gene modify the risk for CP. MATERIALS AND METHODS: DNA samples were obtained from 236 adult CP patients of hereditary (n = 23), alcoholic (n = 137), or idiopathic (n = 76) origin. DNA from 113 healthy controls and from 93 alcoholic controls were analyzed for comparison. Patients and controls were all of Caucasian origin. Genetic polymorphisms (L55M and Q192R) in PON1 were determined by PCR, followed by restriction fragment length polymorphism analyses in all subjects. RESULTS: The frequencies of the PON1-55 alleles did not differ between CP patients and healthy controls. However, the PON1-192Q allele was significantly more common in idiopathic CP patients (OR : 1.5, 95% CI 1.02, 2.5) compared with healthy controls. CONCLUSIONS: These data suggest that the PON1-192Q allele, resulting in partly deficient antioxidant and detoxification activity of this enzyme, might be a risk factor for idiopathic CP in Caucasians.     

Paraoxonase/arylesterase ratio, PON1 192Q/R polymorphism and PON1 status are associated with increased risk of ischemic stroke

Objectives:In recent years, importance of enzyme activity measurements, in addition to genotyping, in epidemiological studies relating paraoxonase 1 (PON1) and vascular disease was emphasized. This is the first report evaluating paraoxonase and arylesterase activities as risk factors for ischemic stroke. In addition, PON1 192Gln(Q)/Arg(R) and 55Leu(L)/Met(M) polymorphisms were also analyzed.Design and methods:The study population was comprised of 108 ischemic stroke patients and 78 controls. Enzyme activities were determined by spectrophotometric assays and for genotyping, standard PCR protocols followed by restriction enzyme digestions were used.Results:The prevalence of the PON1 192RR genotype was increased among stroke patients (16.7%) as compared to controls (9.0%, P = 0.129). Paraoxonase and arylesterase activities and PON1 activity ratio (paraoxonase/arylesterase) were found to be lower in patients than in controls. Logistic regression analysis revealed PON1 activity ratio (odds ratio, OR = 0.697, 95% CI, 0.541 to 0.898, P = 0.005), PON1 192RR genotype (OR = 3.434, 95% CI, 1.159 to 10.178, P = 0.026) and PON1 status (PON1 activity ratio combined with PON1 192RR genotype; OR = 1.406, 95% CI, 1.038 to 1.905, P = 0.028) as significant predictors of stroke.Conclusions:This study identified PON1 activity ratio, PON1 192RR genotype and PON1 status as important risk factors for ischemic stroke.     

Genetic and environmental determinants of the PON-1 phenotype

BACKGROUND: Paraoxonase (PON-1) is a high-density lipoprotein (HDL)-associated enzyme that may protect against cardiovascular disease (CVD), because it hydrolyses oxidized phospholipids of low-density lipoprotein (LDL) and therefore prevents the detrimental effects on the arterial wall. The current report describes the determinants of PON-1 bioavailability and activity. MATERIALS AND METHODS: This is the largest (n = 1527) cross-sectional evaluation performed on PON-1 genotypes (Q192R, T-107C and L55M) and environmental determinants to PON-1 catalytic activity and bioavailability in serum of postmenopausal women. PON-1 catalytic activity and PON-1 bioavailability were measured, in vitro, with a paraoxon hydrolysis assay and a phenylacetate hydrolysis assay, respectively. RESULTS: The major determinant of paraoxon hydrolytic activity is the Q192R genotype, but there was also a relation with the C-107T and L55M genotype, HDL levels and alcohol consumption. Phenylacetate hydrolytic activity was most strongly affected by the C-107T genotype followed by the L55M genotype, HDL levels, alcohol consumption and smoking. CONCLUSIONS: PON-1 Q192R, C-107T and L55M genotype, alcohol consumption, smoking and HDL levels are determinants of serum PON-1 phenotype. The contributions of the genetic markers to the PON-1 phenotype are stronger than the contributions of the lifestyle determinants.