The Potential Role of POR*28 and CYP1A2*F Genetic Variations and Lifestyle Factors on Clozapine and N-DesmethylClozapine Plasma Levels in Schizophrenia Patients.

BACKGROUND: Despite its advantages over other antipsychotics, for treatment-resistant schizophrenia, clinical use of Clozapine (CLZ) is challenging by its narrow therapeutic index and potentially life-threatening dose-related adverse effects. RESEARCH DESIGN AND METHODS: As the potential role in CLZ metabolism is assigned to CYP1A2 enzyme and consequently Cytochrome P450 oxidoreductase (POR) their genetic variations might help to determine CLZ levels in schizophrenia patients. For this purpose, 112 schizophrenia patients receiving CLZ were included in the current study. Plasma CLZ and N-desmethylclozapine (DCLZ) levels were analyzed by using HPLC and genetic variations were identified with the PCR-RFLP method. RESULTS: The patients' CYP1A2 and POR genotypes seemed to not affect plasma CLZ and DCLZ levels whereas in the subgroup analysis, POR *28 genotype significantly influenced simple and adjusted plasma CLZ and DLCZ levels concerning smoking habit and caffeine consumption. CONCLUSIONS: The findings of the present study highlight the importance of both genetic and non-genetic factors (smoking and caffeine consumption) for the individualization of the CLZ treatment. In addition to that, it suggests that the added utility of not only the CLZ metabolizing enzymes but also POR, which is crucial for proper CYP activity, to guide CLZ dosing might be useful for clinical decision-making.

Association between serotonin 2A receptor (HTR2A), serotonin transporter (SLC6A4) and brain-derived neurotrophic factor (BDNF) gene polymorphisms and citalopram/sertraline induced sexual dysfunction in MDD patients.

Sexual dysfunction (SD) is a troublesome adverse effect of selective serotonin reuptake inhibitors (SSRIs). A variety of mechanisms might be involved in the occurrence of SD but the exact mechanism is still not clear. Genetic variations among patients treated with SSRIs are strong determinants of intolerance and poor compliance. The present study aimed to determine the relationship between serotonin-2A receptor (HTR2A) gene -1438A/G and 102T/C polymorphisms, serotonin transporter gene (SLC6A4) 5-HTT-linked polymorphic region (5-HTTLPR) insertion/deletion variant and brain-derived neurotrophic factor (BDNF) gene Val66Met polymorphisms and the occurrence of SD adverse effect in major depressive disorder patients treated with citalopram (CIT) or sertraline (SERT). The result from this investigation revealed that the -1438A/G and 102T/C polymorphisms appear to be associated with the SD induced by CIT. It was also demonstrated that patients receiving SERT, carrying T allele of HTR2A or L allele of 5-HTTLPR more likely to experience SD. Most important overall finding of the study is the combined effects of -1438A/G, 102T/C, and 5-HTTLPR polymorphisms. In a logistic regression model, the occurrence of SD increased with the number of risky alleles. As compared with subjects receiving SERT with few risky (≤2) alleles, those with had 5-6 alleles had an increased SD risk. After all, according to these findings, -1438A/G, 102T/C, and 5-HTTLPR polymorphisms could be considered as promising pharmacogenetic biomarkers in CIT/SERT treatment in major depressive disorder (MDD) patients to avoid the occurrence of SD.

The relationship between the serotonin 2A receptor gene -1438A/G and 102T/C polymorphisms and citalopram/sertraline-induced nausea in major depressed patients.

OBJECTIVE: The aim of the present study was to determine the relationship between the polymorphisms of -1438A/G and 102T/C in the 5-HT2A receptor (HTR2A) gene and nausea/vomiting as a side effect induced by sertraline (SERT) or citalopram (CIT) in patients with major depressive disorder. METHODS: A total of 128 patients were enrolled, 63 patients received CIT, whereas 65 patients were treated with SERT. Nausea/vomiting were assessed with the UKU Side-effects Rating Scale at baseline and at the end of the second and fourth weeks. Polymerase chain reaction-restriction fragment length polymorphism technique was employed to determine genetic differences. RESULTS: We have found that, in the patients treated with CIT, there was a nominally significant difference in the genotypic distribution associated with -1438A/G polymorphism between patients with and without nausea (X2  = 6.15, p = 0.041). Moreover, logistic regression analysis revealed a significant association between nausea/vomiting as a side effect and -1438A/G polymorphism. That is, patients with the G allele were at a higher risk for developing nausea/vomiting (p = 0.044, odds ratio = 2.213). The 102T/C polymorphism in the HTR2A gene had no significant effect on the nausea/vomiting as a side effect among participants treated with either CIT or SERT. CONCLUSION: The present study suggests the association of the HTR2A gene -1438A/G polymorphism with nausea/vomiting as a side effect related to CIT treatment.

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.

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

Oxidative stress is believed to play an important role in the pathogenesis of considerable number of complex diseases. The antioxidant enzymes catalase (CAT) and glutathione peroxidase (GPX) are important components of cell defense against oxidative stress, and polymorphisms in the genes which regulate their expression may contribute to differences in susceptibility of individuals to oxidative damage caused by reactive oxygen species. The aim of this study was to assess the distribution of CAT C-262T and GPX1 Pro198Leu genotypic variants in a Turkish population. Genotyping analyses of CAT and GPX1 were conducted in 250 unrelated, healthy volunteers by the PCR-RFLP assay. The allele frequencies were 0.784 (C) and 0.216 (T) for CAT and 0.636 (C) and 0.364 (T) for GPX1 Pro198Leu. The genotype frequencies were 0.632 (CC), 0.304 (CT), and 0.064 (TT) for CAT and 0.416 (CC), 0.44 (CT), and 0.144 (TT) for GPX1 Pro198Leu. The genotype frequencies did not deviate from Hardy-Weinberg equilibrium. The results are compared with those of other reported populations. They showed marked ethnic group differences.

Association of cytokine gene polymorphisms in CWP and its severity in Turkish coal workers.

BACKGROUND: Cytokines appear to play a key role in some inflammatory reactions affecting the interactions among pro- and anti-inflammatory mechanisms that result in several diseases such as coal workers' pneumoconiosis (CWP). In this study, to determine the cytokine gene profiles of Turkish coal miners, we performed genotyping analysis to investigate the polymorphisms of CWP-related pro-inflammatory (TNFA, IL1A, IL1B, and IL6) and anti-inflammatory cytokines (IL-1RN and TGFB1). An additional goal was to observe whether these cytokine gene polymorphisms influence the development risk and severity of. METHODS: Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. RESULTS: TNFA (-238) gene polymorphism principally affected CWP development and severity (OR = 3.47: 95% CI, 1.12-10.77 and OR = 4.30: 95% CI, 1.25-14.74, respectively) and also risk of CWP (OR = 3.79: 95% CI, 1.37-10.46). The TNFA (-308) variant was associated with a risk for the CWP severity (OR = 2.84: 95% CI, 1.08-7.39). A protective effect of IL6 was found on the development (OR = 0.48: 95% CI, 0.21-0.93) and severity of CWP (OR = 0.37: 95% CI, 0.15-0.91). CONCLUSIONS: We suggest that TNFA (-238) variant may be a risk factor in both development and the severity of CWP, while TNFA (-308) variant seems to be important only in disease severity. On the other hand, IL6 variant may have a protective effect on the development and disease severity.

Polymorphisms of microsomal epoxide hydrolase and glutathione S-transferase P1 in a male Turkish population.

Polymorphic genes encoding drug-metabolizing enzymes may account for interindividual differences in certain types of diseases especially cancer. In this study, microsomal epoxide hydrolase (EPHX1) and glutathione S-transferase P1 (GSTP1) gene polymorphisms were determined among 133 healthy males of a Turkish population. Frequencies of EPHX1 and GSTP1 gene polymorphisms were determined by using the polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) method. The observed genotype frequencies of EPHX1 exon 3 were Tyr113Tyr:50.4%, Tyr113His: 42.1%, His113His: 7.5% and EPHX1 exon 4 were His139His: 69.2%, His139Arg: 28.6%, Arg133Arg: 2.2%. GSTP1 exon 5 genotype frequencies were Ile105Ile: 58.7%, Ile105Val: 35.3%, Val105Val: 6.0% and GSTP1 exon 6 genotype frequencies were Ala114Ala: 85.0%, Ala114Val: 14.3%, Val114Val: 0.7%. These results reveal that the frequencies of EPHX1 and GSTP1gene polymorphisms in a small sampling of males within a Turkish population are similar to European Caucasian populations.

The oxidative DNA base damage in testes of rats after intraperitoneal cadmium injection.

Cadmium is known to be a carcinogenic metal that especially its compounds have sufficient evidence in both humans and experimental animals beneath its environmental effects. Testis tissue is highly sensitive to the effects of cadmium. It is proposed that cadmium also increases oxygen derived free radicals and lipid peroxidation. As indicators of oxidative DNA damage, 6 oxidative DNA bases were determined by using Gas Chromatography/Mass Spectrometry-Selected Ion Monitoring technique. 45 Sprague-Dawley rats (225-300 g) were used as experimental animals and were divided into 3 groups of 15 rats. A single 2 mg NaCl/kg body wt, 0,5 and 1,25 mg CdCl2/kg body wt were injected intraperitoneally to control, low and high dose groups, respectively. 5-OH Cytosine, 8-OH Adenine and Fapy Guanine lesions were elevated significantly in high dose group in the first day. A clear dose-response relationship was seen between dose groups and 8-OH Adenine levels related with time in all periods. There was a significant dose-response relationship in 2-OH Adenine, Fapy Guanine and 8-OH Guanine, especially in the second week suggesting the inhibition of XPA protein by cadmium after first week. In contrast, the observation of a significant decrease of 5-OH Cytosine levels after first week showed that cadmium could not affect the enzymes repairing the cytosine base lesions.

Influence of the delta-aminolevulinic acid dehydratase (ALAD) polymorphism on biomarkers of lead exposure in Turkish storage battery manufacturing workers.

BACKGROUND: The relationship between delta-aminolevulinic acid dehydratase polymorphism (ALAD) and biomarkers of exposure was investigated in Turkish lead workers in this study. METHODS: Seventy two male lead battery manufacturing workers were selected for the study. Blood lead (BPb) and urinary lead (UPb) concentrations were determined by atomic absorption spectrometry. Erythrocyte ALAD activity and urinary 5-aminolevulinic acid (UALA) were measured spectrophotometrically. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to determine the genotype of the ALAD gene. RESULTS: In total, 51 workers (70.8%) had the ALAD 1-1 genotype, whereas 21 workers (29.2%) had the ALAD 1-2 genotype. No significant relationships were found between the two genotypes and BPb, UPb, and ALAD activity. ALAD1 homozygotes showed significantly higher levels of UALA in comparison with those ALAD2 carriers. CONCLUSIONS: ALAD 1-1 individuals might be an increased risk compared to ALAD2 carriers to disturbance in heme biosynthetic pathway in high lead exposure.