Paraoxonase 1 mutations in a Turkish population

The Role of PON1 Variants in Disease Susceptibility in a Turkish Population

Paraoxonase 1 (PON1) enzyme plays a major role in antioxidant defense and protects the cells against reactive species. The most common PON1 Q192R and L55M polymorphisms are responsible for a wide variation of PON1 activity, which showed an up to 13-fold interindividual variation among the same genotype. PON1 genotypes were evaluated with the development of pancreatitis, colorectal cancer, and hypothyroidism in a hospital-based, case-control study. Individuals with rs662 G allele had a two-fold risk of developing hypothyroidism. A weak association was found between rs854560 T allele and pancreatitis. The results were preliminary. Further studies with a larger number and detailed biochemical parameters are needed.

The genetic association between PON1 polymorphisms and osteonecrosis of femoral head: A case-control study

The purpose of this study was to investigate the relationship between Paraoxonase-1 (PON1) gene rs662, rs854555 polymorphisms and osteonecrosis of the femoral head (ONFH) in Han population, northern China.Polymerase chain reaction-restriction fragment length polymorphism was used to determine genotypes of PON1 polymorphisms in 84 patients with ONFH and 96 healthy persons. χ test was used to compare distribution differences of genotype, allele, and haplotype between the case and control groups. The odds ratio (OR) and 95% confidence interval (CI) were calculated to reveal the effects of PON1 polymorphisms on risk of ONFH, and the results were adjusted using logistic regression analysis. The linkage disequilibrium and haplotype analysis were performed with haploview software.That people carrying AA genotype of rs662 were easier to be attacked by ONFH than GG genotype carriers (OR = 2.53, 95% CI = 1.05-6.07, P = .038). Meanwhile, the frequency of A allele in the case group was significantly higher than the controls and it was a risk factor for ONFH (OR = 1.56, 95% CI = 1.03-2.38, P = .038). The A-A haplotype frequency of rs854555-rs662 in PON1 was significantly correlated to the increased susceptibility to ONFH (OR = 2.74, 95% CI = 1.28-5.84).The rs662 polymorphism in PON1 may be associated with ONFH susceptibility, but not rs854555 in Han population, northern China. Additionally, haplotype is also a nonignorable risk factor.

A pilot study assessing the association between paraoxonase 1 gene polymorphism and prostate cancer

OBJECTIVE

We aimed to show the relationship between paraoxonase 1 (PON1) gene polymorphism and the development of prostate cancer (PCa).

MATERIAL AND METHODS

We investigated the association of single nuclotide polymorphisms of PON1 enzyme with the development of PCa risk. A total of 147 male patients were divided into PCa, and control groups. The control group was also divided into two subgroups according to serum prostate specific antigen (PSA) levels as non PCa-high PSA (>4 ng/mL) and non PCa-low PSA (≤4 ng/mL) groups.

RESULTS

The mean ages of the patients were 64.81 years, 63.27 years and 64.22 years in PCa group, non PCa-low PSA and non PCa -high PSA groups, respectively. The mean PSA levels were 10.9 ng/mL, 1.16 ng/mL and 6.63 ng/mL for PCa group, non PCa -low PSA and non PCa -high PSA groups, respectively. In terms of PON1 polymorphisms and allele frequencies, there were no statistically significant differences between PCa and control groups. There was not a statistically significant difference between PCa and non PCa-high PSA groups as for genotypic and allelic frequencies. As a result of this small sample sized hypothetical study of polymorphism, a relationship could not be detected between PCa development and PON1 gene polymorphism.

CONCLUSION

According to the results of this preliminary study, it is thought that more comprehensive future studies are necessary to clarify the possible role of PON1 gene polymorphism in the etiology of PCa.

Phenotype distribution of the paraoxonase gene in patients with cardiac disease

INTRODUCTION

Paraoxonase (PON1) is an enigmatic enzyme with multiple enzymatic properties including arylesterase and lactonase activities besides its ability to hydrolyze the toxic metabolite of parathion, paraoxon. The aim of this study was to determine the phenotype distribution of PON1 in patients with cardiac disease who were classified in coronary artery bypass grafting (CABG), heart valve disease (HVD), heart failure (HF) and ST elevation myocardial infarction (STEMI) groups and healthy subjects as a control group.

MATERIAL AND METHODS

A total of 300 people (100 cardiac surgery (70 CABG and 30 HVD), 70 HF, 30 STEMI patients and 100 healthy controls) were admitted to this study. Individual variations in PON1 were determined using the dual substrate (paraoxon and phenylacetate) method.

RESULTS

The following phenotype distributions were found in the cardiac disease and control groups: cardiac disease group (n = 200): 48.5% (QQ), 42.5% (QR), 9% (RR) and control group (n = 100): 58% (QQ), 39% (QR), 3% (RR). RR (high activity) phenotypic distribution was more common in the cardiac disease group than in controls (p = 0.04). In particular, the frequency of the RR phenotype was two- to three-fold higher in the STEMI and HF patients compared to the controls as well as CABG and HVD groups.

CONCLUSIONS

We found a higher percentage of RR phenotype in STEMI and HF patients compared to a large control group as well as compared to two other groups of cardiac disease patients.

Genetic variation at Q192R and L55M polymorphisms in PON1

Earlier we have reported Q192R allele frequencies among four Indian populations as a part of an investigation of the distribution of Paraoxonase 1 polymorphisms. Here we present the results obtained after screening eleven populations representing different regions of India for Q192R and L55M. Population genetic analysis examining the effect of micro-evolutionary forces at these loci confirmed genetic differentiation at Q192R earlier suggested. The study groups showed high frequencies of L55 and differential distribution of Q192 and R192. Tests for deviation from neutrality indicated heterozygote excess at rs662 which has Q192R polymorphism. Higher levels of heterozygosity at Q192R than L55M might be because of its role in wide substrate specificity of the enzyme. A small but highly significant correlation between genetic and geographic distances was observed in a spatial autocorrelation analysis indicating non-random distribution of Q192 allele. Our findings are pertinent to toxicogenetic studies evaluating risk assessment towards organophosphate compounds among different continental groups.

Allele frequencies of PON1 Q192R polymorphism in four populations of India

The allelic distribution at Paraoxonase 1 (PON1) Q192R polymorphism determines differential sensitivity towards certain organophosphate pesticides. The alleles Q (Glutamine) and R (Arginine) at amino acid position 192 are responsible for the lower and higher activity of the enzyme towards paraoxon respectively, making knowledge of this distribution in different populations vital. This study reports the genotype and allele frequencies of the Gln192Arg polymorphism of PON1 in four populations of India, comprising two caste and two tribal groups hitherto unexamined for this polymorphism. The R allele frequencies in Jat, Meo, Santhal and Zeliangrong populations were found to be 0.47, 0.45, 0.54 and 0.51 respectively. The gene diversity analyses show a high genetic differentiation at this locus indicative of the role of populations' history and other evolutionary forces. A comparison with allele frequencies among 106 populations from different continents showed a concordance with their geographic distribution which will have repercussions in policies targeting pesticide usage.

Paraoxonase 1 and its relationship with pesticide biomarkers in indigenous Mexican farmworkers

OBJECTIVE

Biomarkers of pesticide toxicity and paraoxonase 1 (PON1) phenotype and genotypes were evaluated in indigenous Mexican farmworkers exposed mainly to organophosphate (OP) pesticides.

METHODS

Acetylcholinesterase, butyrylcholinesterase, and PON1 activities--arylesterase and CMPAase activities--were evaluated spectrophotometrically. PON1 55 and 192 polymorphisms were determined by real-time polymerase chain reaction. Hematological parameters were evaluated using a cytometer.

RESULTS

Butyrylcholinesterase and arylesterase activities were lower in farmworkers, who also showed lower levels of leukocytes but higher percentages of lymphocytes when compared with the nonexposed group. Our results showed a high frequency of OP, high hydrolysis-related PON1 alleles (LL/QR and LL/RR) in the study population. An association was observed between CMPAase activity and PON1Q192R polymorphism.

CONCLUSIONS

Our results suggest that pesticide exposure modifies biochemical and hematological biomarkers in the study population, and that the phenotype of PON1 (CMPAase) is a sensible susceptibility biomarker of OP pesticide toxicity.

Significant interethnic differencies in functional variants of PON1 and P2RY12 genes in Roma and Hungarian population samples

Antiplatelet therapy with clopidogrel is one of the most common therapies given to patients worldwide. However, the clinical efficacy and toxicity of clopidogrel is not constant in every patient due to interindividual variations. There are several factors that contribute to these interindividual differencies such as SNPs in genes of specific receptors and enzymes. PON1 (paraoxonase 1) plays an important role in the bioactivation of clopidogrel. Single nucleotide polymorphisms of this gene decrease the activity of paraoxonase enzyme and lead to an unefficient clopidogrel effect. P2RY12 (purinergic receptor P2Y, G-protein coupled, 12) gene is coding a receptor, which is situated on the surface of the platelets and plays a role in ADP-induced platelet aggregation. In this study we investigated 2 functional SNPs of PON1 gene (rs662 and rs854560) and 3 variants of the P2RY12 gene (rs2046934, rs6798347, rs6801273) in samples pooled from average Hungarian Roma and Hungarian population samples with PCR-RFLP method. For the PON1 variants we detected that the R allele frequency was significantly lower in the Roma group compared to the Hungarian population. (0.249 vs 0.318 p < 0.001). By contrast, the frequency of the M allele was significantly higher in Roma than in Hungarians (0.332 vs 0.290 p < 0.05). For the 3 P2RY12 variants we could find significant differencies only in rs2046934: the frequency of the CC genotype is 7 times higher in Hungarians than in Romas (1.4 vs 0.2 %, p < 0.05). The data presented here represent a unique genetic profile in Roma people that has not been reported for other populations.

Effect of PON1 gene polymorphisms in Turkish patients with hepatocellular carcinoma

Background: Reactive oxygen species (ROS) can oxidize biological molecules that mediate carcinogenesis by causing metabolic malfunction and damage to DNA. Human serum paraoxonases (PON1, PON2 and PON3) play a role in antioxidant defense and protect the cell against ROS. PON1 polymorphisms Q192R and L55M have been shown to be associated with several human cancers, but their association with hepatocellular carcinoma (HCC) has yet to be investigated. Methods: We performed genotyping analysis using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in a hospital-based case–control study of 217 confirmed HCC patients and 217 age-, gender-, smoking- and alcohol consumption-matched cancer-free controls in Turkish population. Results: Q192R and L55M polymorphisms were in significant linkage disequilibrium (LD) (D′ = 0.77). However, allele, genotype and haplotype analysis showed no significant differences between the risks of HCC and PON1 polymorphisms. Moreover, no significant differences were found between clinical findings, clinicopathological features and sex in comparison with the PON1 genotypes in HCC group. Conclusion: Our results suggest for the first time that neither the Q192R polymorphism nor the L55M polymorphism has relationship with the risk of developing HCC. Further independent studies are required to clarify the possible role of PON1 gene Q192R and L55M polymorphisms on the risk of developing HCC in a larger series and also in patients of different ethnic origins.

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Human serum paraoxonases (PON) play a key role to protect the cell against ROS.

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We analyzed for the first time the relationship between PON1 polymorphisms and HCC.

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No significant differences between HCC risk and PON1 (L55M, Q192R) polymorphisms

Effect of paraoxonase 1 192 Q/R polymorphism on paraoxonase and acetylcholinesterase enzyme activities in a Turkish population exposed to organophosphate

Organophosphate (OP) compounds are the most commonly used pesticide groups and they are commercially used in the market for local and industrial purposes. Paraoxonase 1 (PON1) enzyme plays an important role in biotransformation of OP compounds, which shows toxic effects via inhibiting the acetylcholinesterase (AChE). The aim of this study was to determine the effects of PON1 gene polymorphism and its effects on PON and AChE enzyme activities in individuals who were exposed to organophosphorus insecticides due to occupational reasons, and to profile the probability of susceptibility to organophosphorus compounds. For this purpose, 54 individuals who were exposed to OPs and 54 healthy unrelated controls were studied. First, PON1 and AChE enzyme activities were measured. Second, PON1 192 Q/R polymorphism was determined by standard polymerase chain reaction–restriction fragment length polymorphism technique. When the PON1 192 Q/R polymorphism was compared with PON1 enzyme activities, statistically significant association was found in both OP-exposed and control groups ( p < 0.05). PON1 192 R(+) (QR + RR genotypes) genotype carriers had higher PON1 activities than 192 R(−) (QQ) genotype carriers. On the other hand, results were statistically analyzed in terms of AChE enzyme activities and there were statistically significant differences only in the OP-exposed group ( p < 0.05). The mean AChE concentration in the OP-exposed group was determined as 33.79 ± 6.84 U/g haemoglobin (Hb) for PON1 192 R(+) carriers and 30.37 ± 7.62 U/g Hb for PON1 192 R(+) carriers. As a conclusion, PON1 and AChE activities were increasing according to the genotypes found in individuals having been exposed to OPs at a chronic level; 192 R(+) > 192 R(−), respectively.

Two- and three-locus haplotypes of the paraoxonase (PON1) gene are associated with coronary artery disease in Asian Indians

INTRODUCTION

In view of the reported association of SNPs in the paraoxonase (PON1) gene with coronary artery disease (CAD), and the absence of conclusive data from India, we investigated the relationship of three SNPs at different loci (-108C/T, L55M and Q192R) of the PON1 gene and their haplotypes with CAD among people residing in the northern plains of India.

MATERIALS AND METHODS

One hundred and seventy-eight healthy controls and two hundred and four angiographically-proven CAD patients were genotyped using PCR-RFLP.

RESULTS

Of the three SNPs, only the R allele of Q192R polymorphism was associated with CAD (p<0.05). Two locus haplotypes QT (OR 0.55, p=0.0004, 95% CI 0.39-0.77, significant) and LQ (odds ratio 0.73, p=0.03, 95% CI 0.55-0.97, trend) showed protective effects, while haplotypes MR (OR=5.36, p=0.0001, 95% CI 2.045-14.049) and MC (OR=2.71, p=0.011, 95% CI 1.221-6.046) were associated with increased risk of CAD. MRT, a minor three-locus haplotype also displayed significant association (OR 4.93, 95% CI 1.7-13.5) with the disease. Significance was assessed after applying Bonferroni's correction.

CONCLUSIONS

Our study revealed that only one SNP at a single locus but several haplotype combinations of PON1 coding and promoter-region polymorphisms were associated with the risk of or protection against CAD. Thus, haplotype analysis brought better insights into the association of PON1 gene polymorphisms with CAD in Asian Indians.

Multifactor dimensionality reduction analysis of MTHFR, PAI-1, ACE, PON1, and eNOS gene polymorphisms in patients with early onset coronary artery disease

BACKGROUND

Association studies in the Turkish population have investigated the single locus effects of different gene polymorphisms on coronary artery disease (CAD). CAD is a complex polygenic disease that involves complex interactions among multiple genetic and environmental conditions.

DESIGN

We evaluated associations of five candidate genetic polymorphisms (methylene tetrahydrofolate reductase C677T, plasminogen activator inhibitor 4G/5G, endothelial nitric oxide synthase (eNOS) 3-27 base pair repeat, insertion, or deletion of a 287 bp Alu repeat sequence polymorhism of angiotensin I converting enzyme, and paraoxonase Gln192Arg PON1 polymorphisms) with the presence and extent of early onset CAD.

METHODS

DNA was isolated and amplified from 90 consecutive patients with angiographically proven early onset CAD (ages 41 ± 5 for men, 49 ± 7 for women) and also from 90 control subjects with no significant coronary obstruction angiographically (ages 42 ± 5 for men, 48 ± 6 for women). Multifactor dimensionality reduction (MDR) analysis was performed to identify a model of CAD based on both genetic and conventional risk factors.

RESULTS

MDR analysis detected a significant model with four genes (prediction success ∼ 61%, p = 0.03). When the total number of the conventional risk factors is analysed with the candidate polymorphisms, a different model is identified that includes three of the four genes from the above model and achieves a similar prediction of CAD as the gene only model.

CONCLUSION

These data indicate that gene-gene and gene-environmental risk interactions form significant models in predicting early onset CAD.

Genetic polymorphism in paraoxonase 1 (PON1): Population distribution of PON1 activity

Paraoxonase-1 (PON1) is a serum esterase that hydrolyzes the activated oxon form of several organophosphates. The central role of PON1 in detoxification of organophosphate (OP) pesticides was demonstrated in knockout mouse studies, suggesting that human variability in PON1 needs to be considered in health risk assessments involving exposure to these pesticides. The current analysis focused on two genetic loci in which polymorphisms demonstrated to affect PON1 activity. Detailed kinetic studies and population studies found that the *192Q (wild type) allele is more active toward some substrates (such as sarin, soman, and diazoxon) and less active toward others (such as paraoxon or chlorpyrifos) relative to the variant *192R allele. Another allele that affects activity is *55M; PON1 enzyme quantity, rather than specific activity or substrate preference, is altered. The *192R variant occurs commonly with a frequency of 25-64% across the populations analyzed. The *55M allele is less common, occurring in 5-40% of individuals depending upon the ethnic group studied. These activity and allele frequency data were incorporated into Monte Carlo simulations in which the frequency of both variant alleles was simultaneously modeled in Caucasian, African American, and Japanese populations. The resulting Monte Carlo activity distributions were bimodal for the substrate paraoxon with approximately fourfold differences between low- and high-activity modal medians. Differences in activity between total population median and 1st percentile were five- to sixfold. When sarin metabolic variability was simulated, the population distributions were unimodal. However, there was an even greater degree of interindividual variability (median to 1st percentile difference >20-fold). These results show that the combined effects of two PON1 allelic variants yielded a population distribution that is associated with a considerable degree of interindividual variability in enzyme activity. This indicates that assessments involving PON1 substrates need to evaluate polymorphism-related variability in enzyme activity to display the distribution of internal doses and adverse responses. This may best be achieved via physiologically based pharmacokinetic (PBPK) models that input PON1 activity distributions, such as those generated in this analysis, to simulate the range of oxon internal doses possible across the population.

Frequency of paraoxonase 192/55 polymorphism in an Iranian population

Paraoxonase (PON1) is a serum enzyme that plays an important role in prevention of atherosclerosis and also protects against organophosphate-induced neurotoxicity. PON1 displays a high variability in human populations. In this study, PON1-192 and -55 polymorphisms and correlation to serum PON1 activity were investigated in 132 healthy Iranian individuals from Isfahan province. The genotype frequencies for PON1-192 were approximately 48% (QQ), 42.% (QR), and 10% (RR) and for PON1-55 17% (MM), 48% (ML), and 35% (LL). Thus, the frequencies of alleles R and L were 0.31 and 0.59, respectively. PON1 activity toward paraoxon was markedly affected in both polymorphic populations in the following order QQ < QR < RR genotype for PON1-192 and MM < ML < LL genotype for PON1-55. Neither polymorphism significantly affected PON1 activity toward phenylacetate. The RR/LL individuals had the highest PON1 activity and QQ/MM individuals the least. The QR/ML haplotype was the most frequent seen in Iranians, and the RR/MM and QR/MM haplotypes were absent in this population. In conclusion, the frequencies of PON1-192 and -55 polymorphisms in this Iranian population were different from those seen in other Asian populations from Japan and China but similar to those for European Caucasians.

Serum paraoxonase and arylesterase activities in patients with lung cancer in a Turkish population

BACKGROUND

Lung cancer (LC) is the leading cause of cancer-related deaths. Oxidative DNA damage may contribute to the cancer risk. The antioxidant paraoxonase (PON1) is an endogenous free radical scavenger in the human body. The aim of this study was to determine serum PON1 and arylesterase (ARE) activities in patients with newly diagnosed LC.

METHODS

This case control study involved a total of 39 patients with newly diagnosed LC (untreated) and same number of age- and sex-matched healthy individuals. Serum PON1 and ARE activities in addition to lipid parameters were measured in both groups.

RESULTS

Serum PON1 and ARE activities were found to be lower in patients with LC compared to the controls (p = 0.001 and p = 0.018, respectively). The ratio of PON1/high density lipoprotein (HDL) was significantly lower in the LC group compared to the control one (p = 0.009). There were positive correlations between the serum levels of HDL and PON1 in both the control (r = 0.415, p = 0.009) and the LC groups (r = 0.496, p = 0.001), respectively. PON1 enzyme activity was calculated as three different phenotypes in both groups. In regard to lipid parameters, total cholesterol levels were significantly lower (p = 0.014) in the LC group whereas the other lipid parameters such as HDL, LDL, and triglyceride levels were not significantly different among groups.

CONCLUSION

Serum PON1 activity is significantly low in the LC group compared with the healthy controls. Metastasis status and cigarette smoking do not affect serum PON1 activity in the LC patients.

Distribution of paraoxonase-1 gene polymorphisms and enzyme activity in a Peruvian population

Paraoxonase-1 (PON1) is a serum esterase associated with high density lipoproteins and capable of detoxifying toxic metabolites of organophosphorus (OP) compounds. Two major polymorphisms have been described in the coding region of the PON1 gene at positions 192 and 55 and at least five in the 5'-regulatory region, the most important at position -108. Depending on the substrate, PON1 192 Q/R polymorphism can affect PON1 enzymatic activity. In the present study, we have determined the distribution of the PON1 192 Q/R and -108 C/T polymorphisms in a Peruvian population and compared the distribution of these polymorphisms with those of other world populations. PON1 phenotype and enzyme activity also were measured as they can influence the population resistance to the toxicity of OP compounds. The genotype distribution at position 192 was: QQ = 0.236, QR = 0.607, and RR = 0.157; and distribution at position -108 was: CC = 0.315, CT = 0.596, and TT = 0.089. The frequencies of the high activity R and C alleles were 0.461 and 0.613, respectively. The frequency of the PON1 192 Q allele was significantly lower than that of American, Caucasian-American, European-Brazilian, and Costa Rican samples. Outside the American continent, the frequency of this allele was lower than for all European countries, Thais, and Indians, but higher than for Chinese or Japanese. Regarding the toxicological importance of these polymorphisms, it was inferred that PON1 phenotyping (assessment of the R alloform) and genotyping (determination of the PON1 -108TT genotype) could be helpful as individual markers of susceptibility. PON1 phenotyping may be useful in further epidemiological studies involving agriculture workers occupationally exposed to OP compounds in developing countries.

8-Hydroxydeoxyguanosine levels in human leukocyte and urine according to exposure to organophosphorus pesticides and paraoxonase 1 genotype

OBJECTIVE

In order to investigate a role of paraoxonase 1 (PON1) polymorphism in organophosphorus (OP)-induced 8-hydroxydeoxyguanosine (8-OHdG) levels, urinary metabolites of OP, PON1 genotypes, and 8-OHdG levels in leukocyte and urine were measured in OP indoor insecticide sprayers and controls in summer and winter.

METHODS

The study population contained 18 male sprayers and age-matched 18 male controls. Sprayers were primarily exposed to OP insecticides (mainly fenitrothion, dichlorvos, chlorpyrifos, and diazinon), and partially to pyrethroids (mainly permethrin) and carbamates (mainly propoxur). Urinary metabolites of OP were measured by gas chromatography-mass spectrometry. 8-OHdG levels in leukocyte and urine were measured by ELISA kit. PON1 genotype was identified using allele-specific fluorogenic TaqMan probes.

RESULTS

The mean concentrations of urinary dimethyl phosphate (DMP) and total dialkyl phosphates (DAP) in summer and those of 8-OHdG in summer and winter were significantly higher in OP sprayers than controls. This resulted in a significant positive correlation between 8-OHdG levels and urinary DMP or DAP, suggesting a correlation between OP metabolites and production of oxidative stress. Of PON1 genotypes, incidences of Q/Q, Q/R, and R/R types were 17, 39, and 44% in OP sprayers and controls, respectively. Although PON1 polymorphism did not contribute to the leukocyte and urinary 8-OHdG levels, the urinary OP metabolite concentrations in summer showed a significant decrease as the number Q allele decreased.

CONCLUSION

These results indicate that an increase in OP metabolites is associated with a high level of oxidative stress in OP sprayers, although the contribution of the PON1 polymorphism to the metabolism of OP is still unclear.

Gln-Arg192 polymorphism of paraoxonase 1 is associated with carotid intima-media thickness in patients of type 2 diabetes mellitus of Chinese

Serum paraoxonase (PON) is a high-density lipoprotein-bound enzyme that can prevent oxidation of low-density lipoprotein by hydrolyzing lipid peroxides and thus exert an anti-atherogenic effect. Recent studies have suggested that glutamine(Q isoform)/arginine(R isoform) polymorphism at position 192 of PON(1) gene is associated with macrovascular disease of type 2 diabetes mellitus (T2DM). We re-investigated this relationship using carotid intima-media thickness (IMT) as a surrogate continuous variable for macroangiopathy. The genotype and allele frequency of PON(1) 192 Q/R polymorphism was assayed by polymerase chain reaction-restriction fragment length polymorphism in 152 type 2 diabetic patients and 128 healthy subjects from a population of Chinese Han nationality in ChengDu area. The carotid IMT was measured by B-mode ultrasonography in type 2 diabetic patients. No differences were found in PON(1) gene Q/R polymorphism in the type 2 diabetic patients when compared with the control group. The mean carotid IMT in type 2 diabetic subjects with the QQ, QR and RR genotype was 0.65+/-0.27, 0.83+/-0.27 and 1.05+/-0.32 mm, respectively. One-way ANOVA showed that IMT was significantly greater in the RR subgroup than in both QR and QQ subgroups (P<0.01). Multivariate logistic regression analysis showed R allele to be the main determinant of IMT variability (OR 4.0 95% CI 2.10-7.40 P=0.005). Our data support the view that 192 R allele of PON(1) gene is a risk factor for macrovascular disease of T2DM in Chinese.

Human serum paraoxonase (PON1) activity in acute organophosphorous insecticide poisoning

Human serum paraoxonase (PON1) and perhaps other mammalian paraoxonases catalyzes the hydrolysis of certain organophosphorus (OP) insecticides and nerve gases and so may alter significantly an individual's susceptibility to the toxicity of these chemicals. Serum PON1 exhibits a substrate dependent polymorphism and this polymorphism shows great interethnic variability. This study focused on the investigation of PON1, arylesterase and cholinesterase activities in 28 acute OP insecticide poisoning cases. Insecticide analysis were performed by GC-NPD and activities of enzymes were measured by using spectrophotometer. The activity levels for salt stimulated PON1, basal PON1 and arylesterase were found as 78.83 (35.39-186.13), 39.97 (2.49-80.43) micromol/min/l and 126.26 (36.34-288.24) mmol/min/l respectively. On the other hand the activity levels for butyrylcholinesterase (BTC) and acetylcholinesterase (AchE) were found as 797.23 (106.3-3823)U/l and 4.65 (0.21-30.29)U/ml. There was a correlation between percent stimulation of PON1 and BTC activities (r=0.446, P<0.05), but this correlation was lower than in cases who exposed to OP insecticides chronically. As a conclusion, in chronic and acute OP exposure, both PON1 level and phenotype must be taken into consideration.

Variability of the paraoxonase gene (PON1) in Euro- and Afro-Brazilians

The human high-density lipoprotein-associated paraoxonase (EC 3.1.1.2; PON1) plays a role in the hydrolysis of organophosphorus compounds and against the oxidative damage of low-density lipoprotein. In the present study, variants of PON1 (55 and 192) were investigated by PCR-RFLP and PCR-SSCA in Euro- (N = 101) and Afro-Brazilians (N = 70). The PON1*55 and PON1*192 allele frequencies were significantly different in these ethnic groups (p < 0.05 and p < 0.001, respectively). The genotype frequencies for PON1*55 (LL, LM, and MM) in Euro- and Afro-Brazilians were 33, 56, and 11% and 47, 49, and 4%, respectively. The genotype frequencies for PON1*192 were significantly different in Euro- and Afro-Brazilians (QQ, QR, RR: 48, 42, and 10% and 21, 52, and 27%, respectively; p < 0.001). The haplotype frequency distributions were also significantly different in Euro- (LQ = 30.20%; LR = 30.69%; and MQ = 39.11%) and Afro-Brazilians (LQ = 24.97%; LR = 46.46%; MQ = 22.18%; and MR = 6.39%; p < 0.001). Linkage disequilibrium (D) in relation to the maximum expected value was higher in Euro- (100%) than in Afro-Brazilians (58%). We suggest that the high linkage disequilibrium in Caucasians and Asians characterized by the absence or very low frequency of the MR haplotype is mainly due to genetic drift and possibly also to natural selection favoring the PON1*192Q allele or a variant in linkage disequilibrium with it. This seems to be the first study on the PON1 variability at the DNA level in South American samples and one of the few studies on individuals of mixed African origin.

How to manage individualized drug therapy: application of pharmacogenetic knowledge of drug metabolism and transport

Significant fractions of health budgets must be spent for treatment of drug side effects and for inefficient drug therapy. Hereditary variants in drug metabolizing enzymes, drug transporters, and drug targets are important determinants of drug response and toxicity and may therefore aid in selection and dosage of drugs. Today there is extensive knowledge of genetic polymorphisms of cytochrome P450 (CYP) enzymes 2A6, 2C9, 2C19, and 2D6; of phase-2 enzymes such as thiopurine S-methyltransferase; and more recently of drug transporters such as the MDR-1 gene-product P-glycoprotein, affecting a significant share of currently used drugs. However, application of pharmacogenetic knowledge to clinical routine is limited in current practice. To promote the application of pharmacogenetic knowledge in clinical routine, research on genotype-based dose adjustments is still necessary - as is the promotion of faster and cheaper genotype analyses. Furthermore, the benefits of CYP genotype-directed drug therapy should be evaluated in properly designed prospective studies. Once such steps have been successfully taken, drug therapy could well become more prevention-directed and patient-tailored than it is possible today, replacing the current "one drug in one dose for one disease" strategy by a more individualized approach.

The human paraoxonase Gln-Argl92 (Q/R) polymorphism in turkish patients with coronary artery disease

It has been suggested that a Q/R (Glnl92Arg) polymorphism of paraoxonase (PON) might be associated with the predisposition to coronary artery disease (CAD). Therefore, we studied the human paraoxonase gene (PON1) polymorphism in Turkish patients with CAD by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). This polymorphism was determined in 96 CAD patients and in 105 control subjects. The frequencies of the QQ, QR, and RR genotypes were found as 36.5, 52.0, and 11.5% in CAD patients and 48.6, 41.0, and 10.4% in control subjects, respectively. The QR genotype was the most common in the patient group, whereas the QQ genotype was more frequent in individuals without CAD. Frequency of the R allele was higher among CAD patients compared to controls (38.5% versus 31%). However, neither the genotype nor the allele distribution of the Gln92Arg polymorphism of PON1 was statistically significantly different between the two groups (P>0.05). Although both systolic and diastolic blood pressure levels were slightly higher in patients with the QQ genotype, there was no differences in regard to age, sex, serum triglyceride, total cholesterol or high-density lipoprotein cholesterol among CAD patients with different PONI Gln192Arg genotypes. In summary, our results suggest that no association exists between the Gln192Arg polymorphism of paraoxonase and CAD in Turkish patients.