PON1 55 and 192 Gene Polymorphisms in Type 2 Diabetes Mellitus Patients in a Turkish Population

Coronary Heart Disease in Type 2 Diabetes Mellitus: Genetic Factors and Their Mechanisms, Gene-Gene, and Gene-Environment Interactions in the Asian Populations

Asians are more susceptible to type 2 diabetes mellitus (T2D) and its coronary heart disease (CHD) complications than the Western populations, possibly due to genetic factors, higher degrees of obesity, insulin resistance, and endothelial dysfunction that could occur even in healthy individuals. The genetic factors and their mechanisms, along with gene-gene and gene-environment interactions associated with CHD in T2D Asians, are yet to be explored. Therefore, the objectives of this paper were to review the current evidence of genetic factors for CHD, summarize the proposed mechanisms of these genes and how they may associate with CHD risk, and review the gene-gene and gene-environment interactions in T2D Asians with CHD. The genetic factors can be grouped according to their involvement in the energy and lipoprotein metabolism, vascular and endothelial pathology, antioxidation, cell cycle regulation, DNA damage repair, hormonal regulation of glucose metabolism, as well as cytoskeletal function and intracellular transport. Meanwhile, interactions between single nucleotide polymorphisms (SNPs) from different genes, SNPs within a single gene, and genetic interaction with environmental factors including obesity, smoking habit, and hyperlipidemia could modify the gene's effect on the disease risk. Collectively, these factors illustrate the complexities of CHD in T2D, specifically among Asians.

Paraoxonase 1 (PON1) L55M and Q192R polymorphisms are not associated with chronic kidney disease in Thai individuals with type 2 diabetes

BACKGROUND

Decreased paraoxonase 1 (PON1) activity and PON1 polymorphisms have been found to be associated with chronic kidney disease (CKD) in type 2 diabetes mellitus (T2DM).

OBJECTIVE

This study aimed to investigate the association of the PON1 L55M and Q192R polymorphisms with CKD in T2DM, as well as their relationship with PON1 activity.

METHODS

A total of 166 T2DM patients, including 83 CKD patients and 83 non-CKD patients, were recruited. Biochemical parameters and paraoxonase (PONase) and arylesterase (AREase) activities were measured. The PON1 L55M and Q192R polymorphisms were analysed by a polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. Data were analysed using the chi-square test, Student's t-test and logistic regression analysis.

RESULTS

Total cholesterol, TGs, LDL-C and Cr were significantly higher in CKD patients than in non-CKD patients. In contrast, the estimated glomerular filtration rate (eGFR) and AREase activity were significantly lower in CKD patients than in non-CKD patients (P < .05). The genotype and allele frequencies of the PON1 L55M and Q192R polymorphisms were not significantly different between CKD and non-CKD patients. Multivariate logistic regression analysis showed no association between the PON1 L55M and Q192R polymorphisms and CKD in T2DM. In addition, among all patients, patients with the PON1 LM genotype had significantly lower PONase activity than those with the LL genotype (P < .05). Among all patients, CKD patients and non-CKD patients, those with the PON1 RR genotype had significantly higher PONase activity but lower AREase activity than patients with the QR and QQ genotypes (P < .05).

CONCLUSIONS

PON1 activity was influenced by the PON1 L55M and Q192R polymorphisms. However, the PON1 L55M and Q192R polymorphisms may not be considered genetic biomarkers for CKD in T2DM.

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.

Evaluation of Relationship Between Arylesterase-Based Activity and Genetic Variants of Paraoxonase1 in T2DM Patients within Golestan Province

Arylesterase activity of Paraoxonase-1 (PON1) enzyme may be play important role in initiation and progression of several diseases. Activity or serum level of Arylesterase can be affected by many genetic alterations such as SNPs. The reduction in the activity and serum level of Arylesterase could be involved in Type2 diabetes mellitus (T2DM). The aim of this investigation is to examine the association between Arylesterase activity and promoter polymorphism (- 108C > T) of PON1gene in patients with T2DM in Golestan Province, northern area of Iran. Achievement of this purpose was due to DNA obtaining from blood then SNP determination using PCR-RFLP and Arylesterase activity measurement in the serum of 90 normal individuals and 90patients suffering diabetes. Data was processed by SPSS software version 16. The significant association was observed between the Arylesterase activity and three genotypes of PON1 gene such as CC, CT, and TT in subjects with T2DM. In the present study, it has been shown level of Arylestrase activity of PON1 in patients (117.33 ± 63.96) is lower than it in control group (289.33 ± 68.38); P < 0.05. Our results declared that activity of Arylesterase in diabetic patients was significantly lower than the healthy individuals.

The most effective polymorphisms of paraoxonase-1 gene on enzyme activity and concentration of paraoxonase-1 protein in type 2 diabetes mellitus patients and non-diabetic individuals: A systematic review and meta-analysis

INTRODUCTION

Many studies have evaluated the association of paraoxonase-1 (PON1) gene polymorphisms with enzyme activity and concentration in type 2 diabetes mellitus (T2DM). However, the exact impact of these polymorphisms is not still obvious. Hence, we conducted a systematic review and meta-analysis to clarify the association of PON1 polymorphisms with its enzyme characteristics in T2DM patients and non-diabetic individuals.

METHODS

We searched electronic databases including PubMed, Web of Science, Embase and Scopus for publications by April 2018. The pooled response ratio (rr) for the association and their corresponding 95% confidence intervals (CIs) were calculated using a fixed-effect model.

RESULTS

Fifteen relevant studies fulfilled our inclusion criteria. The results showed a 1.25-fold increase in total PON1 activity in non-diabetic group against T2DM patients (p-value = 0.024). Also, only Q192R and L55M polymorphisms had sufficient studies to be included in the meta-analysis. All three genotypes of Q192R polymorphism showed significantly different activities between the study groups with the highest pooled effect size for RR genotype (rr_QQ < rr_QR < rr_RR) while this difference was seen only in LL genotype of L55M polymorphism. Therefore, Q192R polymorphism was more correlated with type 2 diabetes mellitus. In case of concentration, there was no significant differences between two groups (p-value = 0.897).

CONCLUSION

Current meta-analysis suggested that the observed difference of total PON1 activity was due to the different activity of various genotypes of PON1 enzyme in case of L55M and Q192R polymorphisms so that LL and RR genotypes had the most important role in the establishment of mentioned difference.

The Associations between Paraoxonase 1 L55M/Q192R Genetic Polymorphisms and the Susceptibilities of Diabetic Macroangiopathy and Diabetic Microangiopathy: A Meta-Analysis

INTRODUCTION

Plenty of studies have focused on the associations of paraoxonase 1 Q192R and L55M genetic polymorphisms with diabetic macroangiopathy and microangiopathy susceptibility, but these associations remain controversial. Therefore, this meta-analysis was conducted to demonstrate these relationships.

METHODS

Relevant studies published in English or Chinese were identified in PubMed, Embase, Wanfang Database, and CNKI by applying specific inclusion and exclusion criteria. Statistical analyses were performed using the STATA 12.0 statistical software.

RESULTS

25 Case-control studies were included in the meta-analyses: six on the association between paraoxonase 1 L55M genetic polymorphism and diabetic macroangiopathy risk, nine on the association between L55M and diabetic microangiopathy risk, 12 on the association between Q192R and diabetic macroangiopathy risk, and 12 on the association between Q192R and diabetic microangiopathy risk. Paraoxonase 1 L55M genetic polymorphism was significantly associated with diabetic microangiopathy susceptibility in the dominant model [odds ratio (OR) 0.53, 95% confidence interval (CI) 0.33-0.83, P = 0.006], the homozygous model (OR 0.37, 95% CI 0.16-0.86, P = 0.021), the allelic contrast model (OR 0.62, 95% CI 0.43-0.90, P = 0.011), the recessive model (OR 12.04, 95% CI 8.02-18.06, P = 0.000), and the heterozygous model (OR 0.57, 95% CI 0.38-0.85, P = 0.006), but L55M was not significantly associated with macroangiopathy susceptibility. Paraoxonase 1 Q192R genetic polymorphism was significantly associated with diabetic macroangiopathy susceptibility in the homozygous model (OR 1.88, 95% CI 1.06-3.32, P = 0.030), the allelic contrast model (OR 1.31, 95% CI 1.02-1.69, P = 0.038), and the recessive model (OR 1.55, 95% CI 1.11-2.16, P = 0.010), but not in the dominant and heterozygous models. Meanwhile, there was no significant association between paraoxonase 1 Q192R genetic polymorphism and diabetic microangiopathy susceptibility.

CONCLUSION

Paraoxonase 1 L55M and Q192R genetic polymorphisms play important roles in diabetic macroangiopathy and microangiopathy susceptibility. Further well-designed studies based on large samples are needed to confirm these results.

The association between paraoxonase 1 activity and the susceptibilities of diabetes mellitus, diabetic macroangiopathy and diabetic microangiopathy

We carried out this meta‐analysis to explore the influence of paraoxonase 1 activity on the susceptibility of diabetes mellitus (DM), diabetic macroangiopathy and diabetic microangiopathy. Relevant studies were identified from PubMed, Web of Science and CNKI without language limitation, following the inclusion and exclusion criteria. Statistical analyses were implemented with the STATA 12.0 statistical software. Thirty‐six case‐control studies were included in the meta‐analyses, in which 35 for the association between paraoxonase 1 activity and DM risk, 8 for diabetic macroangiopathy and 7 for diabetic microangiopathy. Paraoxonase 1 activity was significantly associated with the susceptibility of DM in pooled population (SMD = −1.37, 95% CI = −1.79 ∼ −0.96, P = .000), and Asians (SMD = −2.00, 95% CI = −2.56 ∼ −1.44, P = .000), but not in non‐Asians (SMD = −0.44, 95% CI = −0.91 ∼ 0.03, P = .069). However, marked heterogeneity was existed (I² = 98.10%, P = .000) and subgroup analyses failed to investigate the sources of heterogeneity. Then, meta‐regression was performed and found that ethnicity could explain the observed between‐study heterogeneity (P = .002). Meanwhile, significant associations were found between paraoxonase 1 activity and diabetic macroangiopathy (SMD = −1.06, 95% CI = −1.63 ∼ −0.48, P = .000) and diabetic microangiopathy (SMD = −0.72, 95% CI = −1.32 ∼ −0.13, P = .018). In conclusion, paraoxonase 1 activity plays important roles in the risk of DM, diabetic macroangiopathy and microangiopathy with ethnicity differences. Further studies with large sample and well design are needed to confirm these results.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

European versus Asian differences for the associations between paraoxonase-1 genetic polymorphisms and susceptibility to type 2 diabetes mellitus

Many studies have examined the associations between paraoxonase‐1 (PON1) genetic polymorphisms (Q192R, rs662 and L55M, rs854560) and the susceptibility to type 2 diabetes mellitus (T2DM) across different ethnic populations. However, the evidence for the associations remains inconclusive. In this study, we performed a meta‐analysis to clarify the association of the two PON1 variants with T2DM risk. We carried out a systematic search of PubMed, Embase, CNKI and Wanfang databases for studies published before June 2017. The pooled odds ratios (ORs) for the association and their corresponding 95% confidence intervals (CIs) were calculated by a random‐ or fixed‐effect model. A total of 50 eligible studies, including 34 and 16 studies were identified for the PON1 Q192R (rs662) and L55M (rs854560) polymorphism, respectively. As for the PON1 Q192R polymorphism, the 192R allele was a susceptible factor of T2DM in the South or East Asian population (OR > 1, P < 0.05) but represented a protective factor of T2DM in European population (OR = 0.66, 95% CI = 0.45–0.98) under a heterozygous genetic model. With regard to the PON1 L55M polymorphism, significant protective effects of the 55M allele on T2DM under the heterozygous (OR = 0.77, 95% CI = 0.61–0.97) and dominant (OR = 0.80, 95% CI = 0.65–0.99) genetic models were found in the European population, while no significant associations in the Asian populations under all genetic models (P > 0.05). In summary, by a comprehensive meta‐analysis, our results firmly indicated that distinct effects of PON1 genetic polymorphisms existed in the risk of T2DM across different ethnic backgrounds.

Association between promoter polymorphism (-108C>T) of paraoxonase1 gene and it's paraoxonase activity in patients with Type2 diabetes in northern Iran

Type 2 diabetes mellitus (T2DM) is one of the diseases which depend on the obesity associated with insulin resistance. Various factors, such as a reduction in the activity of paraoxonase-1 enzyme (PON1), could affect T2DM. PON1 is a multifunctional enzyme with paraoxonase and arylesterase activities. The Activity of PON1 is influenced by various SNPs. The aim of presence study is to investigate the association between promoter polymorphism (-108C>T) of PON1 gene and its paraoxonase activity in patients suffering from Type 2 diabetes in Golestan Province, north of Iran. To this end, genomic DNA was extracted from whole blood then genotyping was carried out using PCR-RFLP and enzymatic activity of paraoxonase was measured in the serum of 90 healthy subjects and 90 diabetic patients. Data was analyzed using SPSS version 16. The relationship between the level of paraoxonase activity with polymorphisms of CC, CT, and TT was statistically significant in patients with T2DM. There was a significant association between polymorphism C-108>T of PON1 and type2 diabetes mellitus, with 24.4% of control group subjects and 15.5% of patients having CC genotype; p<0.05. The ratio for CT genotype in target and control groups was 51.1% and 61.1% respectively; p<0.05. TT genotype was 33.3% in patients and 14.4% in the control group; p<0.05. In the present study, the highest frequency belonged to CT genotype in both the control and the target groups, followed by CC genotype in control group and TT genotype in target group. Our findings revealed that paraoxonase activity of PON1 in the control group was significantly higher in comparison with diabetic patients.

The Q192R polymorphism of the paraoxonase-1 (PON1) gene is associated with susceptibility to gestational diabetes mellitus in the Greek population

A key factor protecting from oxidative stress in gestational diabetes mellitus (GDM) and in type 2 diabetes (T2D) is paraoxonase-1 (PON1). Inconclusive and limited data exist regarding the effect of a coding polymorphism (Q192R) of the PON1 gene in conferring susceptibility to both states. In the present study, we investigated the association between the PON1 gene and the risk for GDM in the Greek population and assessed for the first time its transcriptional efficiency. We studied 185 women with GDM and 104 non-diabetic controls for the PON1 polymorphism. For PON1 mRNA expression, peripheral leucocytes were harvested from 20 GDM and 20 control women, harboring different genotypes for the polymorphism, using real-time quantitative PCR. The RR genotype and the R allele of the PON1 Q192R polymorphism were significantly associated with an increased risk for GDM (p = 0.012 and p < 0.0001, respectively). Furthermore, there was no statistical correlation between the individual metabolic parameters tested and the three genotypes. Finally, the expression levels of PON1 mRNA in GDM patients did not exhibit any statistical difference compared with normal controls (p = 0.138). These data independently document that the Q192R polymorphism is closely associated with GDM susceptibility, while the PON1 gene expression is not impaired in GDM.

Serum paraoxonase level and paraoxonase polymorphism in patients with acromegaly

BACKGROUND

Acromegalic patients have increased cardiometabolic risk factors due to an elevation of growth hormone (GH) levels. Human serum paraoxonase (PON), a high-density lipoprotein (HDL)-related enzyme, is one of the major bioscavengers and decreases the oxidation of low-density lipoprotein (LDL), a key regulator in the pathogenesis of atherosclerosis. In this study, we investigated a potential relationship between serum PON levels or PON polymorphisms and acromegaly.

METHODS

A total of 48 acromegalic patients and 44 healthy controls were included in this study. Serum GH levels, insulin-like growth factor-1 levels and lipid profiles were measured. Serum PON levels, as well as PON 1 L55M and Q192R gene polymorphisms, were examined.

RESULTS

No significant differences were found in terms of age, gender, presence of diabetes, serum LDL cholesterol (LDL-C), HDL-C, or triglyceride levels between the case and control groups (P > 0.05). A statistically significant difference was found in serum PON levels between the cases and controls (P = 0.007). The median serum PON level was 101 ± 63.36 U/l in the case group and 63 ± 60.50 U/l in the control group. There was a significant correlation between serum PON levels and IGF-1 levels (P = 0.004, r = 0.319); however, no significant differences were found in PON1 L55M and PON Q192R polymorphisms between the patients and controls (P = 0.607 and P = 0.308, respectively). In addition, no significant differences were found in serum PON levels in acromegalic patients who were and were not in remission (P = 0.385), nor between those with PON1 L55M and Q192R polymorphisms (P = 0.161 and P = 0.336, respectively).

CONCLUSIONS

Elevated serum PON levels were detected in acromegalic patients, independently of their remission status. This suggests protective effects for cardiometabolic risk parameters.

Oxidative stress-related genes in type 2 diabetes: association analysis and their clinical impact

Worldwide prevalence of diabetes mellitus motivates a number of association studies to be conducted throughout the world. Eleven polymorphisms from nine candidate genes in oxidative stress pathway have been analyzed in eastern Indian type 2 diabetic patients (n = 145) and healthy controls (n = 100). Different biochemical parameters were also analyzed for their association with the disease. Significant associations were observed for rs2070424 A>G SOD1 (OR 3.91, 95% CI 2.265-8.142, P < 0.001), rs854573 A>G PON1 (OR 3.415, 95% CI 2.116-5.512, P < 0.001), rs6954345 G>C PON2 (OR 3.208, 95% CI 2.071-4.969, P < 0.001), RAGE rs1800624 -374 T>A (OR 3.58, 95% CI 2.218-5.766, P < 0.001), and NOS3 -786 T>C (OR 3.75, 95% CI 2.225-6.666, P < 0.001). Haplotype containing two risk alleles of PON1 and PON2 genes was significantly associated with disease (OR 8.34, 95% CI 1.554-44.804, P < 0.002). Our results suggest that carriers of major and efficient alleles of oxidative stress genes are more likely to survive the comorbid complications and single copy of risk allele is sufficient for developing the disease.

Genetic polymorphisms in paraoxonase 1 and G protein-coupled receptor 77, and the risk of glucose-6-phosphate dehydrogenase deficiency in a Saudi population

Objectives:

To investigate the role of amino acid substitution variants Q192R and C698T in the development of glucose-6-phosphate dehydrogenase (G6PD) deficiency in a Saudi male population.

Methods:

This case-control study was carried out in 200 Saudi male individuals: 100 patients with G6PD deficiency, and 100 control subjects collected between July and August 2011 in the Taif region of Saudi Arabia. A total of 2100 male Saudi individuals were screened by a fluorescence spot test, and 100 with G6PD deficiency were selected. Two common variants PON1 (rs662) and C5L2 (rs149572881) were genotyped using polymerase chain reaction followed by restriction fragment length polymorphism analysis.

Results:

The results showed that the R allele and QR genotype were associated with the Q192R polymorphism in PON1 (R versus Q odds ratio [OR], 1.72; 95% confidence interval [95% CI], 1.1-2.6; p=0.01; and QR versus QQ: OR, 1.98; 95% CI, 1.1-3.6; p=0.02). All the C698T genotypes and allele frequencies in C5L2 were almost similar in both the cases and controls (CT versus CC: OR, 2.04; 95% CI, 0.3-11.4; p=0.40; and T versus C: OR, 2.02; 95% CI, 0.3-11.1; p=0.41).

Conclusions:

These findings suggest the association of PON1 with G6PD deficiency in the Saudi male population studied herein. Future studies, including correlation analyses between the clinical features and genotypes in populations of different ethnicities, are warranted to confirm the disease association with these genetic mutations.

Paraoxonase1 genetic polymorphisms in a mixed ancestry African population

Paraoxonase 1 (PON1) activity is markedly influenced by coding polymorphisms, Q/R at position 192 and M/L at position 55 of the PON1 gene. We investigated the frequencies of these polymorphisms and their effects on PON1 and antioxidant activities in 844 South African mixed ancestry individuals. Genotyping was done using allele-specific TaqMan technology, PON1 activities were measured using paraoxon and phenylacetate, oxidative status was determined by measuring the antioxidant activities of ferric reducing antioxidant power and trolox equivalent antioxidant capacity, and lipid peroxidation markers included malondialdehyde and oxidized LDL. The frequencies of Q192R and L55M were 47.6% and 28.8%, respectively, and the most common corresponding alleles were 192R (60.4%) and 55M (82.6%). The Q192 was significantly associated with 5.8 units' increase in PON1 concentration and 15.4 units' decrease in PONase activity after adjustment for age, sex, BMI, and diabetes, with suggestion of differential effects by diabetes status. The PON1 L55 variant was associated with none of the measured indices. In conclusion, we have shown that the Q192R polymorphism is a determinant of both PON1 concentration and activity and this association appeared to be enhanced in subjects with diabetes.

Impact on offspring methylation patterns of maternal gestational diabetes mellitus and intrauterine growth restraint suggest common genes and pathways linked to subsequent type 2 diabetes risk

Size at birth, postnatal weight gain, and adult risk for type 2 diabetes may reflect environmental exposures during developmental plasticity and may be mediated by epigenetics. Both low birth weight (BW), as a marker of fetal growth restraint, and high birth weight (BW), especially after gestational diabetes mellitus (GDM), have been linked to increased risk of adult type 2 diabetes. We assessed DNA methylation patterns using a bead chip in cord blood samples from infants of mothers with GDM (group 1) and infants with prenatal growth restraint indicated by rapid postnatal catch-up growth (group 2), compared with infants with normal postnatal growth (group 3). Seventy-five CpG loci were differentially methylated in groups 1 and 2 compared with the controls (group 3), representing 72 genes, many relevant to growth and diabetes. In replication studies using similar methodology, many of these differentially methylated regions were associated with levels of maternal glucose exposure below that defined by GDM [the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study] or were identified as changes observed after randomized periconceptional nutritional supplementation in a Gambian cohort characterized by maternal deprivation. These studies provide support for the concept that similar epigenetic modifications may underpin different prenatal exposures and potentially increase long-term risk for diseases such as type 2 diabetes.

Relationship between the paraoxonase 1 gene glutamine 192 to arginine polymorphism and gestational diabetes mellitus in Saudi women

OBJECTIVES

Gestational diabetes mellitus (GDM) is recognized as an imbalance between insulin resistance and insulin secretion, leading to maternal hyperglycemia. Previous studies in a Saudi population indicated a high frequency of Paraoxonase 1 glutamine 192 to arginine (PON1 Q192R) polymorphism, suggesting this polymorphism as an additional risk factor. The present study was designed to explore the possible association between the PON1 Q192R polymorphism and GDM in a Saudi population.

METHODS

This case-control study was carried out in 500 pregnant women, including 200 GDM cases and 300 non-GDM women. Genotyping for PON1 Q192R (rs662) variants was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The results of the present study indicates that Q192R polymorphism was significantly associated with GDM in a Saudi population with the minor allele frequency (MAF) (p=0.0007). Q192R genotypes and alleles showed a strong association with GDM (p=0.009 and p=0.0007, respectively).

CONCLUSION

In conclusion, these findings suggest that the PON1 Q192R polymorphism has high MAF in GDM in the studied Saudi population.

Can paraoxonase 1 polymorphisms (L55 M and Q192 R) protect children with type 1 diabetes against lipid abnormalities?

BACKGROUND

Only a few studies have focused on the possible modulatory role of paraoxonase 1 (PON1) polymorphisms in lipid profiles, especially in children and in adolescents with type 1 diabetes (T1D).

OBJECTIVE

We propose to study the association between PON1 polymorphisms (PON1-55 and PON1-192) and a lipid profile in a young Tunisian population with T1D.

METHODS

The study compared 122 children and adolescents with T1D with 97 controls. Genomic DNA was collected from 116 patients and 91 controls. Lipid parameters were determined by automated methods. PON1 activity was measured by a spectrophotometric method and genotyping of the PON1 gene was assessed by multiplex polymerase chain reaction followed by restriction fragment-length polymorphism.

RESULTS

A significant increase in total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol (LDL-C), apolipoprotein B (ApoB), and lipoprotein (a) (Lp(a)) and a significant decrease in apolipoprotein A1 (ApoA1), ApoA1/ApoB ratio, and PON1 activity/HDL-C ratio were observed in children with T1D compared with controls. In the LLQR haplotype, the group with diabetes showed significantly higher values of total cholesterol, LDL-C, apoB, Lp(a), and apoA1/apoB ratio compared with the control group. Those with diabetes with the LLQQ haplotype showed a significant decrease in LDL-C and Lp(a) compared with controls (P < .0001).

CONCLUSION

PON1 polymorphisms (PON1-55 and PON1-192) seem to be involved in the altering the lipid profile in T1D. The LLQR haplotype provided an atherogenic lipid profile in children with T1D compared with controls. LLQQ haplotype seemed to have a protective effect against the increase in LDL-C and Lp(a) that are heavily involved in the development of cardiovascular diseases.

Association of paraoxonase gene polymorphisms with diabetic nephropathy and retinopathy

Emerging reports have revealed a potential association of paraoxonase (PON) gene polymorphisms with diabetic nephropathy (DN) and diabetic retinopathy (DR). However, the identification of susceptible genes and the quantification of associated risks are elusive owing to a lack of reproducibility. Therefore, a meta‑analysis was conducted in the present study to improve the understanding of the effect of PON1 and PON2 on DN and DR. A total of 10 articles, involving 2,877 patients and 3,246 controls met the inclusion criteria. Functional variants (n=4) were evaluated, including rs662 (p.Q192R) and rs854560 (p.L55M) in PON1; and rs7493 (p.S311C) and rs12026 (p.A148G) in PON2. Overall, PON1‑L55M was found to be significantly associated with DR in all the genetic models: allele [odds ratio (OR)=2.42; 95% confidence interval (CI), 1.91‑3.07]; dominant (OR=5.76; 95% CI, 3.14‑10.55), homozygote (OR=10.53; 95% CI, 5.59‑19.86), heterozygote (OR=3.62; 95% CI, 1.94‑6.74), and recessive (OR=3.56; 95% CI, 2.61‑4.86), with no evidence of between‑study heterogeneity. However, such associations were not detected in DN and the other three polymorphisms did not show any associations with DN or DR. The current meta‑analysis highlighted results for the risk of association of PON1‑55L with DR. The results also indicated that PON2 gene polymorphisms, as well as PON1‑Q192R, may not confer major genetic risk to DN or DR. Additional studies are required to enrich the understanding of PON genes, particularly for its functional role in DR.

Implications of serum paraoxonase activity in obesity, diabetes mellitus, and dyslipidemia

Human serum paraoxonase 1 (PON1) is an enzyme with esterase activity, and is physically bound to high-density lipoproteins (HDL). It plays a key role in the action of HDL toward protection of lipoprotein and biological membrane against oxidative damage. It may have a protective role against atherosclerosis by virtue of its action on hydrolyzing lipid peroxides and preventing accumulation of phospholipids in oxidized low-density lipoprotein (LDL). PON1 is hypothesized to be an indicator of the risk of atherosclerosis and coronary artery disease development. Numerous studies have implicated PON1 activity in relation to various endocrine disorders. The current article reviews the clinical perspectives of PON1 activity with regards to obesity, diabetes mellitus with its complications, and dyslipidemia.

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.

Association of PON1 and PON2 polymorphisms with PON1 activity and significant coronary stenosis in a Tunisian population

PON1 and PON2 have attracted considerable attention as candidate genes for coronary heart disease because their enzymes function as key factors in lipoprotein catabolism pathways. We studied the distribution of PON1 and PON2 polymorphisms, including genotyping, lipid profile, and PON1 activity, and their association with PON1 activity and significant coronary stenosis (SCS) in a Tunisian population. PON1 activity was lower in patients with SCS than in controls. It increased with the R allele (QQ < QR < RR) in PON1-192 genotypes and with the L allele (MM < ML < LL) in PON1-55 genotypes. In the presence of metabolic syndrome and diabetes, PON1-192RR and PON2-311CC were associated with an increased risk of SCS and PON1-55MM seems to have lower risk. This association was evident among nonsmokers for PON1-55MM and among smokers for PON1-192RR and PON2-311CC. The GTGC haplotype seemed to increase the risk of SCS compared with the wild haplotype in a Tunisian population.

The Past and Present of Paraoxonase Enzyme: Its Role in the Cardiovascular System and Some Diseases

Although paraoxonase is synthesized in many tissues including the heart, colon, kidneys, lungs, small intestines and brain, its major locus of synthesis is the liver. PON1 is in close association with apolipoproteins and protects LDL against oxidation. It was reported that PON1 quantities dropped to 40 times lower than normal in cardiovascular diseases and diseases like diabetes, ulcerative colitis, Crohn's disease, chronic renal failure, SLE, Behcet's disease, cancer, hepatitis B, obesity, metabolic syndrome, Alzheimer's and dementia. It is speculated that the concerning decline in serum PON1 amount results from single nucleotide polymorphism in the coding (Q192R, L55M) and promoter (T-108C) sites of the PON1 gene. Additionally, circulating amounts of PON1 are affected by vitamins, antioxidants, fatty acids, dietary factors, drugs, age and lifestyle. This collection attempts to review and examine the past and present studies of paraoxonase and its relation with the cardiovascular system and some relevant diseases.

Paraoxonase 1 polymorphisms L55M and Q192R were not risk factors for Parkinson's disease: a HuGE review and meta-analysis

PURPOSE

The Paraoxonase 1 (PON1) has been studied as a potential candidate gene for Parkinson's disease risk, but direct evidence from genetic association studies remains inconclusive. We performed a meta-analysis pooling data from all relevant studies in order to determine the effects of two PON 1 polymorphisms (L55M and Q192R) on Parkinson's disease.

METHODS

We applied a random effects to combine odds ratio (OR) and 95% confidence intervals. Q statistic was used to evaluate the homogeneity, and Egger's test and Funnel plot were used to assess publication bias. In secondary analyses, we examined dominant and recessive models as well.

RESULTS

Concerning the PON1 L55M polymorphism, we identified 9 eligible studies (a total of 2582 cases and 3997 controls). The random effects pooled OR was OR=1.29, (0.90, 1.84). Concerning the Q192R polymorphism, we identified 7 eligible studies (a total of 2582 cases and 3997 controls). The random effects pooled OR was OR=1.08(0.81, 1.43). Analysis with dominant and recessive genetic models yielded the same inferences as genotype-based comparisons for both of the two polymorphisms.

CONCLUSION

The results of this meta-analysis suggested that both PON1 L55M and Q192R were not responsible for PD.

Serum paraoxonase-1 (PON1) activities (PONase/AREase) and polymorphisms in patients with type 2 diabetes mellitus in a North-West Indian population

OBJECTIVE

Paraoxonase-1 (PON1), an HDL-C associated enzyme, protects lipoproteins from oxidation. There is evidence that PON1 enzyme activity is reduced in the patients with type 2 diabetes mellitus (T2DM). North-West Indian Punjabis, a distinct ethnic group has high incidence of T2DM. However till date there is no information regarding PON1 enzyme activities and PON1 polymorphisms in T2DM patients of this ethnic group.

METHODS

We identified polymorphisms in the coding Q192R, L55M and promoter -909G/C, -162A/G, -108C/T of the PON1 gene by using PCR-RFLP, multiplex PCR and allele specific oligonucleotide PCR assays in 250 T2DM patients and 300 healthy controls. We also assessed paraoxonase (PONase) and arylesterase (AREase) activities of PON1 enzyme.

RESULTS

The serum PONase (114.2 vs. 178.0nmol/min/ml) and AREase (62.7 vs. 82.5μmol/min/ml) activities were significantly lower (p<0.0001) in patients as compared to controls. PONase activity was affected by all the studied PON1 polymorphisms. However, AREase activity was not affected by any of these polymorphisms. Coding Q192R and promoter -909G/C polymorphisms showed significant differences in genotypic distribution. QR, RR (Q192R) and GC, CC (-909G/C) genotypes and L-C-A-R-G, L-T-A-R-G, L-T-G-Q-C haplotypes showed significant association with type 2 diabetes. No significant linkage disequilibrium was observed among the five polymorphisms.

CONCLUSION

Both PONase and AREase activities are lower in patients and this could lead to increased lipid peroxidation and accelerated atherosclerosis in them. PONase activity, but not AREase activity is influenced by PON1 polymorphisms. QR, RR, GC, CC genotypes and L-C-A-R-G, L-T-A-R-G, L-T-G-Q-C haplotypes are commoner in diabetics as compared to controls and may be related to genetic susceptibility to type 2 diabetes.