CAT C-262T and GPX1 Pro198Leu polymorphisms in a Turkish population

Exposure to heavy metals, antioxidant status, and the interaction of single nucleotide polymorphisms in the genes CAT rs7943316, GSTP1 rs1695, as well as GSTM1 and GSTT1 genes, among workers in occupational settings

Individuals working in diverse fields are consistently exposed to work-related pollutants that can impact their overall health. The current study investigated the presence of pollutants in seven different occupational groups and their impact on human health. Biochemical and genetic approaches were employed. Heavy metals were determined by ICP-MS technique. Oxidative stress biochemical markers and molecular analysis of the glutathione transferases gene SNPs (GSTT1, GSTM1, GSTP1), catalase (CAT, rs7943316), and superoxide dismutase (SOD, rs17880487) was carried out. The results revealed a significantly higher quantity of Cd among five occupational groups. Catalase, malonaldehyde, and glutathione was significantly dysregulated. Molecular analysis of the gene SNPs suggests a probable relationship between the antioxidants and the phenotypic expression of the CAT, GSTP1, GSTT1, and GSTM1 SNPs. It is concluded that chronic exposure to occupational contaminants like Cd affects human health through oxidative stress in association with some of their gene SNPs.

Oxidative-Stress Related Gene Polymorphism in Endometriosis-Associated Infertility

Background and Objectives: Endometriosis is a benign inflammatory disease associated with infertility and chronic pelvic pain, estimated to affect 7−10% of reproductive-age women, with the possibility of malignant transformation. Recent studies focus on oxidative stress and genetic mutations as risk factors in the pathophysiology of endometriosis-associated infertility. Materials and Methods: This case-control study is the first in Eastern European women that aimed to investigate four genes’ genetic polymorphisms that encode antioxidant enzymes involved in oxidative stress (glutathione peroxidase 1, GPX1 198Pro > Leu, catalase CAT-262C > T, glutathione S-transferase M1, and T1 null genotype) and their association with endometriosis-related infertility. We compared 103 patients with endometriosis-associated infertility with 102 post-partum women as the control group. Results: The endometriosis group had a mean age of 34.5 +/− 6.12 years, while the control group’s mean age was 35.03 +/− 5.95 years. For CAT-262C > T polymorphism, the variant genotypes were significantly more frequent in the endometriosis group. Moreover, for the GPX1 198Pro > Leu, the endometriosis group had significantly more frequent CT and TT genotypes. The null genotype of GSTM1 was detected significantly higher in the endometriosis group. No significant differences were found in the frequency of GSTT1 between the two groups. This study suggests that GPX1 198Pro > Leu, CAT-262C > T, and GSTM1 polymorphisms may be risk factors and that the association between the GSTM1-GSTT1 null genotype may play a significant role in endometriosis-associated infertility. Moreover, this study suggests that the GSTT1 null genotype does not influence the disease. Visual identification of endometriotic lesions with microscopic confirmation is the accepted gold standard for diagnosing endometriosis, but general anesthesia and laparoscopy are required. Conclusions: In this regard, a panel of genetic or laboratory markers is needed for the early diagnostics of this prevalent disease, especially in the case of young patients with future pregnancy intention.

Predisposition of SOD1, GPX1, CAT genetic variants and their haplotypes in cataractogenesis of type 2 diabetes mellitus in Pakistan

AIMS

Cataract formation is accelerated by hyperglycemia due to the excessive production of oxidative stress. This study aimed to examine the underlaying role of glutathione peroxidase 1 (GPX1) rs1800668, catalase (CAT) rs1001179 and superoxide dismutase 1 (SOD1) 50 bp Indel promotor region variants in the pathogenesis of cataract in patients with diabetes.

METHODS

A population-based case-control study of n=680 individuals was conducted which comprised of four respective groups: type 2 diabetes mellitus, diabetic cataract, senile cataract patients and controls. Screening of genotypes was performed by allele-specific (AS) and conventional polymerase chain reaction (PCR). Statistical testing was carried out using SPSS© 20.0, MedCal© and SNPStats© software's. Bioinformatics analysis of linkage disequilibrium was done by HaploView© software 7.0.

RESULTS

GPX1 (rs1800668) showed significant association with higher susceptibility of opacification in type 2 diabetes mellitus (χ²=23.0, Adjusted OR=1.63, 95% CI: 1.05-2.49, p<0.001). A protective role was anticipated by CAT variant (rs1001179) for the development of resistance against the pathogenicity of cataract with diabetes (χ² = 107, Adjusted OR=0.17, 95% CI: 0.10-0.29, p<0.001). Linkage disequilibrium (LD) plot of GPX1 and CAT variants revealed that CTC-CTT haplotypes demonstrated the presence of linkage (D'=1.0) and co-inheritance (LOD=13.84) in patients of diabetic cataract.

CONCLUSIONS

GPX1 (rs1800668) variant may serve as an antioxidant biomarker for the assessment of risk for cataract in type 2 diabetes mellitus. GPX1 enzyme owed an antioxidant activity which can reduce the oxidative stress and hence could develop resistance in cataractogenesis. The findings could be beneficial as a potential target to the future pharmacogenomic studies of cataract prevention and eradication in diabetes mellitus.

Contribution of glutathione peroxidase 1 (Pro200Leu) single nucleotide polymorphism and serum homocysteine levels in the risk of acute myocardial infarction in Egyptians

Background

Oxidative stress is among the most common risk factors in the pathogenesis of acute myocardial infarction (AMI). Glutathione peroxidase 1 enzyme coded by the GPX1 gene plays an essential role in reducing oxidative stress. Previous studies correlated the GPX1 (Pro200Leu) single nucleotide polymorphism (SNP) with AMI incidence. Elevated homocysteine (Hcy) levels induce oxidative stress and are considered an independent risk factor for AMI. Evidence showed a complex relationship between Hcy and GPx-1 activity. This study examined the association of the common (Pro200Leu) SNP in GPX1 with AMI incidence in an Egyptian population. This study is the first to check this association in an Egyptian population. Moreover, the association between serum Hcy and the incidence of AMI was checked, and the novelty was to statistically correlate GPX1 Pro200Leu genotypes with serum Hcy levels in patients and control subjects. Hundred control subjects and hundred and twenty AMI patients were genotyped using PCR-RFLP analysis. An ELISA was used to measure serum Hcy levels.

Results

The GPX1 (Pro200Leu) genotype distribution and allele frequency were not significantly different between patients and control subjects (P = 0.60 and P = 0.62, respectively). Serum levels of Hcy were significantly elevated in patients compared to control subjects (P ≤ 0.0001). However, no significant difference was observed in serum Hcy levels among different GPX1 genotypes in neither patients nor control subjects.

Conclusions

The minor T allele of GPX1 Pro200Leu is not associated with AMI risk in this Egyptian population. However, high homocysteine serum levels might contribute independently to the risk of AMI. Finally, Hcy levels were not significantly different in homozygous minor TT compared to homozygous wild CC.

Association between superoxide dismutase 2, glutathione peroxidase 1, xeroderma pigmentosum group d gene variations, and head and neck squamous cell cancer susceptibility

As oxidative stress is implicated in the pathogenesis of head and neck squamous cell cancer (HNSCC), the functions of antioxidant enzyme systems and DNA repair proteins are critical in the development of cancer. To investigate the role of genetic polymorphisms of the antioxidant superoxide dismutase 2 (SOD2) Val16Ala, glutathione peroxidase 1 (GPX1) Pro198Leu, and the DNA repair Xeroderma Pigmentosum Group D (XPD) Lys751Gln genes under exogenous risk factors, including smoking and alcohol consumption, in HNSCC carcinogenesis, we conducted a case-control study on 139 unrelated cases and 265 non-cancer controls. Polymorphisms were analyzed in additive, dominant and recessive genetic models, individually and in an interaction model. Carriers of the T allele of SOD2 were associated with an increased risk for HNSCC in the overall subgroups of males and smokers; similarly, the T allele of GPX1 was associated with elevated risk in the overall and smoker subgroup. A 12.47-fold increased risk was observed for the carriers of GPX1 TT, SOD2 CT and XPD CC genotypes for HNSCC. This is the first study presenting the potential roles of SOD2, GPX1 and XPD polymorphisms in interaction and under three genetic models in the development of HNSCC. The results suggest that these polymorphisms slightly modify the risk in HNSCC development individually but are significantly higher when they functioned and were evaluated together.

An investigation of the relation between catalase C262T gene polymorphism and catalase enzyme activity in leukemia patients

INTRODUCTION

Catalase (CAT), an antioxidant enzyme, catalyzes conversion of hydrogen peroxide to water and molecular oxygen, protecting cells against oxidative stress. The aim of this study was to investigate the possible association between CAT C262T polymorphism in the promoter region of the CAT gene and leukemia risk and to determine the relationship between CAT genotypes and CAT enzyme activities.

MATERIAL AND METHODS

Genotypes of 102 cases and 112 healthy controls' genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism methods. Catalase activity was measured with the method of Aebi.

RESULTS

The frequencies of the T allele among the cases and controls were 28.4% and 25.9%, respectively (p = 0.75). The frequencies of CC, CT, and TT among cases were 57.8%, 27.4%, and 14.7%, respectively, while in controls, the frequencies of CC, CT, and TT were 54.4%, 39.3%, and 6.3%, respectively, which were not significantly different. Although CAT enzyme activity was lower in leukemia patients with TT genotypes than in controls, this did not reach statistical significance (p = 0.37).

CONCLUSIONS

This is the first report showing that CAT C262T polymorphism is not a genetic predisposing factor for the risk of leukemia in the Turkish population. However, additional research is needed to confirm these findings.

Denatonium Benzoate-Induces Oxidative Stress in the Heart and Kidney of Chinese Fast Yellow Chickens by Regulating Apoptosis, Autophagy, Antioxidative Activities and Bitter Taste Receptor Gene Expressions

Simple Summary

Denatonium benzoate is a strong bitter taste receptor agonist, extensively used for its activation of different cell pathways. Taste signals have been associated to food recognition and avoidance, and bitter taste provokes an aversive reaction and is assumed to protect chickens from consuming poisons and harmful toxic substances. The results of the study revealed that dietary supplementation with medium and high doses of denatonium benzoate damaged the epithelial cells of the heart and kidneys by inducing apoptosis and autophagy and reduced the growth of chickens, respectively. However, mRNA expressions of bitter taste receptors, downstream signaling effector genes, apoptosis-, autophagy- and antioxidant-related genes were higher on day 7, while these expressions were subsequently decreased on day-28 in the heart and kidney of Chinese Fast Yellow chickens in a dose-response manner.

Abstract

The sense of taste which tells us which prospective foods are nutritious, poisonous and harmful is essential for the life of the organisms. Denatonium benzoate (DB) is a bitter taste agonist known for its activation of bitter taste receptors in different cells. The aim of the current study was to investigate the mRNA expressions of bitter taste, downstream signaling effectors, apoptosis-, autophagy- and antioxidant-related genes and effector signaling pathways in the heart/kidney of chickens after DB dietary exposure. We randomly assigned 240, 1-day-old Chinese Fast Yellow chicks into four groups with five replicates of 12 chicks and studied them for 28 consecutive days. The dietary treatments consisted of basal diet and feed containing DB (5, 20 and 100 mg/kg). The results revealed that dietary DB impaired (p < 0.05) the growth performance of the chickens. Haemotoxylin and eosin staining and TUNEL assays confirmed that medium and high doses of DB damaged the epithelial cells of heart/kidney and induced apoptosis and autophagy. Remarkably, the results of RT-PCR and qRT-PCR indicated that different doses of DB gradually increased (p < 0.05) mRNA expressions of bitter taste, signaling effectors, apoptosis-, autophagy- and antioxidant- related genes on day 7 in a dose-response manner, while, these expressions were decreased (p < 0.05) subsequently by day-28 but exceptional higher (P < 0.05) expressions were observed in the high-dose DB groups of chickens. In conclusion, DB exerts adverse effects on the heart/kidney of chickens in a dose-response manner via damaging the epithelium of the heart/kidney by inducing apoptosis, autophagy associated with bitter taste and effector gene expressions. Correlation analyses for apoptosis/autophagy showed agonistic relationships. Our data provide a novel perspective for understanding the interaction of bitter taste, apoptosis, autophagy and antioxidative genes with bitter taste strong activators in the heart/kidney of chicken. These insights might help the feed industries and pave the way toward innovative directions in chicken husbandry.

A Novel PCR-RFLP Method for Detection of POR*28 Polymorphism and its Genotype/Allele Frequencies in a Turkish Population

BACKGROUND

The Cytochrome P450 (CYP) enzymes are involved in the metabolism of many endogenous and exogenous substances. They need electrons for their activity. CYP mediated oxidation reactions require cytochrome oxidoreductase (POR) as an electron donor. A common genetic variation identified in the coding region of POR gene (POR*28) leads to an alteration in POR activity by causing amino acid change. The current study aimed to determine the allele and genotype frequencies of POR*28 in a healthy Turkish population by using a novel genotyping assay.

METHODS

A novel PCR-RFLP assay was developed for the detection of POR*28 (rs1057868) polymorphism and the obtained frequencies were compared with the data established in various ethnic groups.

RESULTS

Genotypic analysis revealed that of 209 healthy, unrelated individuals tested for POR*28 polymorphism, 55.5% of the studied subjects were homozygous for the CC genotype, 34.9% were heterozygous for the CT genotype and 9.6% were homozygous for the TT genotype. The allele frequencies were 0.73 (C) and 0.27 (T). The present results were in accordance with the Hardy- Weinberg equilibrium. The distribution of POR*28 allele varies between populations. The frequency of the T allele among members of the Turkish population was similar to frequencies in Caucasian populations but was lower than in Japanese and Chinese populations.

CONCLUSIONS

In this study, a novel method was developed, which could be applied easily in every laboratory for the genotyping of POR *28 polymorphism. The developed genotyping method and documented allele frequencies may have potential in understanding and predicting the variations in drug response/adverse reactions in pharmacotherapy and susceptibility to diseases in POR-mediated metabolism reactions.

Association of polymorphisms in genes coding for antioxidant enzymes and human male infertility

PURPOSE

Although oxidative stress is thought to be an important cause of male infertility, primarily due to DNA and cell membrane damage, little is known about the genetic causes underlying suboptimal function of the seminal enzymatic antioxidant system. The aim of this study was to investigate the relationship of four potentially functional polymorphisms associated with oxidative stress pathway genes (superoxide dismutase-SOD2 lle58Thr and SOD2 rs4880, catalase-CAT C-262T, glutathione peroxidase 1-GPX1 Pro200Leu) and two null variants of the glutathione S transferase (GSTT and GSTM) genes and infertility risk.

METHODS

A case control study was conducted on 313 infertile patients and 80 fertile donors. Each ejaculate was subjected to a seminal analysis that included the classical parameters seminal volume, sperm concentration, sperm motility, and sperm morphology, as well as sperm DNA fragmentation (patients only). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and PCR multiplex methods were carried out for genotyping.

RESULTS

Statistically significant differences were found between fertile donors and infertile patients for SNP CAT C-262T; the CC genotype was related with a twofold increased risk of infertility (odds ratio [OR] = 2.262; 95% confidence interval [CI] = 1.369-3.733; P = 0.001), whereas the CT genotype was associated with a protective effect (OR = 0.401; 95% CI = 0.241-0.667; P = 0.001). Surprisingly, the SOD2 Ile58ssThr SNP was not represented in the sample population, so its frequency in the current population frequenting fertility clinics in Madrid may be very low.

CONCLUSIONS

Our results suggest that the CAT SNP C-262T is potentially associated with an increased risk of male infertility.

Clinical variables and ethnicity may influenced by polymorphism of CAT -262C/T and MnSOD 47C/T antioxidant enzymes in Algerian type1 diabetes without complications

The latest studies in Algeria show that the frequency of type 1 diabetes (T1D) without complications is lower than that with complications and represents a significant burden in terms of cost and treatment. For this reason, we are interested in uncomplicated type1 diabetes and risk factors that are related to polymorphisms of antioxidant enzymes in order to prevent its complications. A total of 260 blood samples of young Algerian adults were examined. The genotypic analysis of Catalase gene (CAT -262C/T, rs1001179) and the superoxide dismutase gene (MnSOD 47C/T, rs4880) was performed by real-time PCR using TaqMan technology. The genotypic distribution of the CAT -262C/T promoter gene's polymorphism showed a significant difference between control and T1D patients for the CC genotype (p = 0.009; OR = 0.30) and for the T allele (p = 0.002; OR = 2.82). In addition, the genotypic distribution of the MnSOD 47C/T gene showed an association with T1D for the CT genotype (p = 0.040; OR = 2.37). Our results revealed that polymorphisms of CAT and MnSOD may be associated with physiopathology causing the onset of T1D. Our data, suggest that the genotypic frequencies of these SNPs appear to be influenced by clinical variables and by the Arab-Berber ethnic origin of the Algerian population.

Catalase C-262T Gene Variant in Patients with Bronchial Asthma

Bronchial asthma (BA) is a chronic inflammatory disease of the airways in the pathogenesis of which oxidative stress has a very important role. Single nucleotide polymorphisms (SNPs) in catalase gene may result in decreased antioxidative defense capacity, and thus a higher risk for BA development. Since oxidative stress has an important role in the pathogenesis of BA and catalase has a key role in antioxidant defense, the aim of this study was to examine the association of CAT C-262T polymorphism with BA in Serbian patients with BA.

A total of 170 subjects (79 patients with BA and 91 controls) were screened for CAT C-262T SNP using PCR-RFLP method.

The analysis of genotype distribution did not show statistically significant differences between BA patients and controls (p > 0.05). Moreover, no differences were detected when comparison was performed based on dominant or recessive model. The distribution of CAT-262C and CAT-262T alleles did not show differences between patients and healthy controls (p = 0.715; OR = 1.091; 95% CI = 0.684–1.741). Further analysis of genotype and allele distributions, based on stratification by sex, did not show significant differences between BA patients and controls (p > 0.05).

This is the first study that examined CAT C-262T (rs1001179) SNP in Serbian patients with BA. The results obtained in this study showed that biallelic SNP at the position-262 in the catalase gene is not associated with BA in the Serbian population.

Oxidative stress gene polymorphisms may have an impact in the development of ischemic stroke

BACKGROUND

Antioxidants are responsible for detoxification of harmful effects of reactive oxygen species. Genetic factors may influence antioxidant activity as a result of polymorphisms on antioxidant enzymes. These polymorphisms can be risk in ischemic stroke (IS) risk. IS is a disorder with genetic and environmental factors contributing to overall risk. Although a few studies have been conducted, there have been no reports on catalase (CAT C262T), manganese superoxide dismutase (MnSOD Ala16Val) and glutathione peroxidase 1 (GPX1 Pro198Leu) gene polymorphisms and IS risk.

METHODS

We aimed to perform a case-control study to increase the awareness of the impact of oxidative stress (OS) gene polymorphism in the development of IS. A restriction fragment length polymorphism-polymerase chain reaction was used to determine genotypes. The interactions between genes and smoking and possible risk factors were evaluated.

RESULTS

An approximately four-fold higher IS risk was found in patients with the Val allele compared to the Ala allele. Smoking was a risk factor in the development of IS for CAT TT and MnSOD Ala/Val genotypes; we found a 3.5- to 5.5-fold higher IS risk in CAT TT and MnSOD Ala/Val genotypes. Different logistic regression models were performed for possible risk factors (smoking, body mass index, low-density lipoprotein and diabetes mellitus). The IS risk increases statistically significant only with age by multiple logistic regression analysis. CAT gene polymorphisms in IS patients were not different from controls.

CONCLUSIONS

It is unlikely that CAT and GPX1 single nucleotide polymorphisms are risk factors for IS. The results of the present study show that smoking may be a risk factor for IS risk in patients with MnSOD mutant genotypes.

Pro198Leu Polymorphism in the Glutathione Peroxidase 1 Gene Contributes to Diabetic Peripheral Neuropathy in Type 2 Diabetes Patients

Glutathione peroxidase 1 (Gpx1) is an endogenous antioxidant enzyme. The T allele of the Pro198Leu polymorphism in the Gpx1 (rs1050450, 198C > T) gene is associated with reduced enzyme activity. The aim of this study was to evaluate the association between Pro198Leu polymorphism and risk of diabetic peripheral neuropathy (DPN). We examined 1244 T2DM patients and 730 healthy controls. In the patient group, 33 % had diabetic peripheral neuropathy. All subjects were genotyped for the Gpx1 Pro198Leu polymorphism by polymerase chain reaction and restriction analysis. A significant increase in the T allele and TT genotype frequencies was observed in DPN patients compared to those without DPN (OR 1.55, 95 % CI 1.30-1.85 and 1.89, 95 % CI 1.30-2.74, respectively). The association remained significant after correction for age, disease duration, HbA1c and BMI. When distribution of T allele was compared between DPN+ and DPN- subgroups and controls, OR was 1.54 for DPN+ and 1.00 for DPN- patients. In conclusion, our findings suggest that Gpx1 Pro198Leu genotypes are significantly associated with the risk of diabetic peripheral neuropathy in patients with T2DM. The study provides new clinically relevant information regarding genetic determinants of susceptibility to diabetic neuropathy.

Influence of Gender and SNPs in GPX1 Gene on Biomarkers of Selenium Status in Healthy Brazilians

Selenium (Se) status varies worldwide as a result of natural variation of Se content in soils, dietary pattern, and the presence of SNPs. Further, Se status in Brazilians and its relationship between genetic variation and Se biomarkers is unknown. This work investigated the association between SNPs in glutathione peroxidase genes and biomarkers of Se status in healthy Brazilians. The study was conducted in 116 healthy adults in São Paulo, Brazil. Plasma and erythrocyte Se were measured by HGFAAS. Erythrocyte GPx (eGPx) activity was measured spectrometrically in a biochemical analyzer. Genotypes were determined by real-time PCR using Taqman(®) Assays. eGPx activity was higher in females compared with males. Lower erythrocyte Se concentrations were found in heterozygous GC carriers for GPX1 rs8179169. eGPx activity was higher in females with the common genotypes, except for rs8179169. GC carriers for rs8179169 had lower erythrocyte Se in both genders, and only male carriers of the variant alleles of both rs1050450 and rs1800668 had higher eGPx activity. In conclusion, the genotype for SNPs in GPX1 and gender affected biomarkers of Se status in this pilot study with healthy Brazilians.

From Six Gene Polymorphisms of the Antioxidant System, Only GPX Pro198Leu and GSTP1 Ile105Val Modulate the Risk of Acute Myeloid Leukemia

Oxidative stress might contribute to the occurrence of cancers, including the hematological ones. Various genetic polymorphisms were shown to increase the quantity of reactive oxygen species, a phenomenon that is able to induce mutations and thus promote cancers. The purpose of the study was to evaluate the association between CAT C262T, GPX1 Pro198Leu, MnSOD Ala16Val, GSTM1, GSTT1, and GSTP1 Ile105Val gene polymorphisms and acute myeloid leukemia risk, in a case-control study comprising 102 patients and 303 controls. No association was observed between AML and variant genotypes of CAT, MnSOD, GSTM1, and GSTT1 polymorphisms. Our data revealed a statistically significant difference regarding the frequencies of GPX1 Pro198Leu and GSTP1 Ile105Val variant genotypes between AML patients and controls (p < 0.001). Our results showed no association in the distribution of any of the CAT C262T, GPX1 Pro198Leu, GSTM1, GSTT1, and GSTP1 polymorphisms regarding age, gender, FAB subtype, cytogenetic risk groups, FLT3 and DNMT3 gene mutations, and overall survival. Our data suggests that the presence of variant allele and genotype of GPX1 Pro198Leu and GSTP1 Ile105Val gene polymorphisms may modulate the risk of developing AML.

Superoxide Dismutase and Catalase Genotypes in Pediatric Migraine Patients

This study compared superoxide dismutase (SOD) and catalase (CAT) alleles in 97 consecutive children and adolescents with migraine to 96 healthy children and adolescents. Isolated genomic DNA was used as a template for SOD1 (35 A/C), SOD2 16 C/T, and CAT2 [(-262 C/T) and (-21 A/T)] allele genotyping. The SOD2 16 C/T genotype and C allele frequency differed significantly between controls and migraine (P = .047; P = .038). CAT -21 AA genotype and A allele frequency were significantly higher in both migraine with aura patients (P = .013; P = .004) and migraine without aura patients (P = .003; P = .001) compared to controls. To our knowledge, this is the first demonstration of differences in SOD and CAT genotypes between pediatric migraine patients and age-matched controls. Further studies on the functional implications of these genetic variants on neural antioxidant capacity and the use of antioxidant modulators for migraine treatment are warranted.

Interaction of Polymorphisms of Resistin Gene Promoter -420C/G, Glutathione Peroxidase -1 Gene Pro198Leu and Cigarette Smoking in Nonalcoholic Fatty Liver Disease

BACKGROUND

Many studies have suggested that cigarette smoking and polymorphisms of resistin and glutathione peroxidase-1 (GPx-1) genes are closely correlated with the pathogenesis of nonalcoholic fatty liver disease (NAFLD). However, few reports have investigated these associations with respect to NAFLD susceptibility. We, therefore, examined the distribution of polymorphisms in GPx-1 and resistin genes in NAFLD patients and healthy controls and analyzed the relationship between these polymorphisms and smoking status.

METHODS

Nine hundred NAFLD patients and 900 healthy controls were selected, and the genetic polymorphisms of resistin gene promoter-420C/G and GPx-1 gene Pro198Leu were analyzed by polymorphism-polymerase chain reaction (PCR) in DNA extracted from peripheral blood leukocytes. Interactions between the two mutants and the gene-environment interaction with cigarette smoking were also analyzed.

RESULTS

Genotype frequencies of -420C/G (GG) and Pro198Leu (LL) were significantly higher in NAFLD cases (49.56% and 50.11%, respectively) compared with healthy controls (23.67% and 24.22%, respectively) (P = 0.0069; P = 0.0072). Moreover, the risk of NAFLD with -420C/G (GG) was significantly higher than in controls (odds ratio [OR] =3.1685, 95% confidence interval (CI) =1.9366-5.2073). Individuals carrying Pro198Leu (LL) had a high risk of NAFLD (OR = 3.1424, 95% CI = 1.7951-5.2367). Combined analysis of the polymorphisms showed that the -420C/G (GG)/Pro198Leu (LL) genotype was significantly more common in the NAFLD group than in the control group (39.44% vs. 12.78%, respectively, P = 0.0054), while individuals with -420C/G (GG)/Pro198Leu (LL) had a high risk of NAFLD (OR = 5.0357, 95% CI = 3.1852-7.8106). Moreover, the cigarette smoking rate in the NAFLD group was significantly higher than in the control group (OR = 1.8990, P = 0.0083 in the smoking index (SI) ≤400 subgroup; OR = 5.0937, P = 0.0051 in the SI >400 subgroup), and statistical analysis suggested a positive interaction between cigarette smoking and -420C/G (GG) (γ = 5.6018 in the SI ≤400 subgroup; γ = 4.4770 in the SI >400 subgroup) and Pro198Leu (LL) (γ = 5.7715 in the SI ≤400 subgroup; γ = 4.5985 in the SI >400 subgroup) in increasing the risk of NAFLD.

CONCLUSION

NAFLD risk factors include -420C/G (GG), Pro198Leu (LL) and cigarette smoking, and these three factors have a significant additive effect on NAFLD risk.

The impact of CYP2C19 polymorphisms on citalopram metabolism in patients with major depressive disorder

WHAT IS KNOWN AND OBJECTIVE

Genetic variations in drug-metabolizing enzyme genes change drug pharmacokinetics and response. CYP2C19 is a clinically important enzyme that metabolizes citalopram (CIT). The objective of this study was to determine CYP2C19 genetic polymorphisms and to evaluate the impact of these polymorphisms on the metabolism of citalopram in a sample of the Turkish population. We also assessed *17 polymorphism in healthy subjects in this population.

METHODS

The CYP2C19 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism method (209 healthy individuals and 50 patients for CIT metabolism), and the plasma concentrations of CIT and demethylcitalopram (DCIT) were quantified by high-performance liquid chromatography.

RESULTS AND DISCUSSION

The CYP2C19*1 and *17 allele frequencies for the patient group and the healthy group were 71·0%, 18·0% and 81·1%, 18·9%, respectively. There was no significant difference between the two groups (P > 0·05). The mean plasma concentrations and the mean dose-corrected (C/D) plasma levels of DCIT were significantly higher in patients with the CYP2C19*1/*1 genotype compared to patients with CYP2C19*1/*2 and CYP2C19*2/*2 genotypes (P < 0·05). Furthermore, the mean metabolic ratio (MR, CIT/DCIT) was also significantly higher in the CYP2C19*1/*2 + CYP2C19*2/*2 genotypes (P < 0·05). On the other hand, plasma CIT, DCIT concentrations and M/R value in the CYP2C19*1/*1 genotypes were no different to those of the CYP2C19*1/*17 genotypes (P > 0·05).

WHAT IS NEW AND CONCLUSION

Our data suggest that CYP2C19*17 polymorphism does not have a significant effect on CIT metabolism. In contrast CYP2C19*2 polymorphism has a prominent role and is likely to contribute to interindividual variability in CIT metabolism in vivo at therapeutic doses.

Gene variants encoding proteins involved in antioxidant defense system and the clinical expression of Wilson disease

BACKGROUND & AIMS

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism resulting from pathogenic mutations of the ATP7B gene. The basis of phenotypic variability of the disease is not understood. The main mechanism of copper toxicity is probably related to generation of intracellular oxidative stress. To evaluate whether interindividual variability within genes encoding proteins involved in antioxidant defense system may modulate phenotypic expressions of WD.

METHODS

Variability within genes encoding the cytosolic enzymes: glutathione peroxidase (GPX1 rs1050450) and manganese superoxide dismutase (SOD2 rs4880), and peroxisomal enzyme: catalase (CAT rs1001179) were analysed in 435 patients. Individual genotypes were tested for their relationship with phenotypic features of WD.

RESULTS

GPX1 genotypes were not related to phenotypic manifestations of WD. Among males homozygocity for the SOD2 rs4880 T allele was related to earlier onset of WD. Patients homozygous for the CAT rs1001179 T allele characterized with later onset of WD [median (interquartile range) age: 29.0 (14.0) years vs. 22.0 (12.0) years, respectively, P < 0.004], later manifestation of hepatic symptoms [34.5 (14.0) years vs. 22.0 (12.0) years, P < 0.0009], and later presentation of neurological symptoms [37.0 (16.0) years vs. 28.0 (13.0) years, P < 0.03] than those having one or two C alleles.

CONCLUSION

Variability within the CAT gene may be an important modifier of the clinical course of WD. SOD2 genotype may influence WD phenotype among males. These observations indirectly confirm a role of oxidative stress in the pathogenesis of WD, as well as indirectly suggest that peroxisomes impairment may be involved in WD pathophysiology.

CAT, GPX1, MnSOD, GSTM1, GSTT1, and GSTP1 genetic polymorphisms in chronic myeloid leukemia: a case-control study

Oxidative damage at the DNA level may be promoted by high levels of reactive oxygen species (ROS), leading to genomic instability and increased neoplastic risk. Superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) enzymes are implicated in the prevention of DNA damage by ROS. The aim of the study was to investigate the relationships between CAT C262T, GPX1 Pro198Leu, MnSOD Ala16Val, GSTM1, GSTT1, and GSTP1 Ile105Val polymorphisms and the risk of CML. No association was observed between CML and variant genotypes of GPX1, MnSOD, GSTM1, and GSTT1 polymorphisms in any of the investigated cases. Our study suggests that the homozygous variant genotype of the GSTP1 Ile105Val gene polymorphisms may be associated with the risk of developing CML (OR = 2.5; 95% CI = 1.08–5.7; P value = 0.02), while the heterozygous genotype of the CAT C262T polymorphism seems to have a protective effect against CML (OR = 0.59, 95% CI = 0.39–0.89, P value = 0.01). In most cases, no association was found between laboratory parameters and prognostic factors and the variant genotype of investigated gene polymorphisms. We concluded that CAT, GPX, MnSOD, GSTM1, and GSTT1 gene polymorphisms are not associated with the risk of CML. Variant genotype of the GSTP1 Ile105Val gene polymorphisms may contribute to the risk of developing CML.

Allele and genotype frequencies of CYP2B6 in a Turkish population

Increasing interest in cytochrome P450 2B6 (CYP2B6) genetic polymorphism was stimulated by revelations of a specific CYP2B6 genotype significantly affecting the metabolism of various drugs in common clinical use in terms of increasing drug efficacy and avoiding adverse drug reactions. The present study aimed to determine the frequencies of CYP2B6*4 CYP2B6*5, CYP2B6*6, CYP2B6*7 and CYP2B6*9 alleles in healthy Turkish individuals (n = 172). Frequencies of three single nucleotide polymorphisms were 516G>T (28%), 785A>G (33%), and 1459C>T (12%). The frequencies of CYP2B6*1, *4, *5, *6, *7, and *9 alleles were 54.3 (95% CI 49.04-59.56), 6.4% (95% CI 3.81-8.99), 11% (95% CI 7.69-14.31), 25.3% (95% CI 20.71-29.89), 0.87% (95% CI -0.11-1.85) and 2.0% (95% CI 0.52-3.48), respectively. Allele *6 was more frequent (25.3%) than the other variant alleles in Turkish subjects. The frequencies of CYP2B6*4, *5, *6, *7, and *9 alleles were similar to European populations but significantly different from that reported for Asian populations. This is the first study to document the frequencies of the CYP2B6*4, *5, *6, *7, *9 alleles in the healthy Turkish individuals and our results could provide clinically useful information on drug metabolism by CYP2B6 in Turkish population.

Frequency of polymorphism -262 c/t in catalase gene and oxidative damage in Slovak children with bronchial asthma

INTRODUCTION

Bronchial asthma is a complex disease in which genetic factors, environmental factors and oxidative damage are responsible for the initiation and modulation of disease progression. If antioxidant mechanisms fail, reactive oxygen species damage the biomolecules followed by progression of the disease. Catalase is one of the most important endogenous enzymatic antioxidants. In the present study, we examined the hypothesis that increased oxidative damage and polymorphism in the CAT gene (-262 promoter region, C/T) are associated with childhood bronchial asthma.

PATIENTS AND METHODS

Genotyping of the polymorphisms in the CAT gene in healthy (249) and asthmatic children (248) was performed using polymerase chain reaction-restriction fragment length polymorphism. Markers of oxidative damage: content of sulfhydryl groups and thiobarbituric acid-reactive substances were determined by spectrophotometry in children.

RESULTS

The TT genotype of catalase was more frequent among the asthmatic patients (22.6%) than in healthy children (4.8%) (odds ratio=5.63; 95% confidence interval=2.93-10.81, P<.001). The amount of sulfhydryl groups decreased significantly and conversely, the content of thiobarbituric acid-reactive substances increased significantly in bronchial asthma and in catalase TT genotype compared to other catalase genotypes of this gene.

CONCLUSIONS

These results suggest that catalase polymorphism might participate in development of bronchial asthma and in enhanced oxidative damage in asthmatic children. Genetic variation of enzymatic antioxidants may modulate disease risk.

Phenotype and genotype relationship of glutathione peroxidase1 (GPx1) and rs 1800668 variant: the homozygote effect on kinetic parameters

GPx1 is one of the most important enzymes involved in oxidative balance so that, we studied the phenotype and genotype relationship of GPx1 activity and rs 1800668 (C/T) site and also evaluated the changes of GPx1 kinetic parameters in the rs 1800668 homozygotes. One hundred fifty eight subjects were recruited after clinical exams. The rs 1800668 (C/T) genotype distribution was identified using RFLP-PCR method. The hemolysate GPx1 activity was spectrophotometrically measured in a reaction coupled with glutathione reductase (GR). The GPx1 enzyme was purified using gel filtration chromatography with Sephacryl S-300 column and, Km(app) was studied in the rs 1800668 TT and CC homozygotes. The results showed that the GPx1 activity is significantly associated to the rs 1800668 (C/T) genotype distribution (P<0.05) so that, the GPx1 activity was high among the CC homozygotes (P<0.03). In addition, Km(app) for TBHP substrate in the TT homozygote (8.48 μM) was higher than the CC homozygote (5.74 μM). We concluded that the C allele within rs 1800668 position is related to the GPx1 activity and may be a potential factor involved in development of inflammatory events.