N-acetyltransferase 2 Slow Acetylator Research Articles

Evaluation of NMP22 in bladder cancer patients sensitive to environmental toxins.

Bladder cancer (BC) is recognized as environmentally related. The interaction of environmental exposure to chemicals and genetic susceptibility seem to play important roles in BC development. In order to improve diagnosis and the recognition of BC risk, a group of markers which combine genetic susceptibility with detoxification and nuclear matrix protein (NMP22) is proposed. The aim of the study was to examine the utility of nuclear matrix protein (NMP22) as a diagnostic marker in BC in genetic susceptibility (NAT2 slow acetylators) combined with detoxification abilities (glutathione S-transferase GST and isoenzyme GST-π). The NMP22 level in urine, N-acetyltransferase 2 (NAT2) genotype and GST activity in hemolysate blood, as well as isoenzyme GST-π level, were determined in the urine and serum of 43 patients with BC and from 25 non-cancer controls. NMP22 and isoenzyme GST-π levels were measured by ELISA. The NAT2 genotype was examined in DNA isolated from whole blood using the PCR (Polymerase Chain Reaction) technique, while the activity of GST was determined with the spectrophotometric method. In the BC group, NMP22 (p = 0.005) concentration, GST-π (p = 0.003) in urine and GST (p = 0.009) activity in blood were statistically significantly higher than in the healthy controls. The majority of BC patients were slow acetylators (NAT2 genotype). A correlation between the level of nuclear matrix protein NMP22 and GST was found in all BC group (p = 0.007) and also slow acetylators (p = 0.0147). The results support the utility of a marker combination, which covers the genetic susceptibility to chemicals with the level of detoxification and nuclear matrix protein in BC patients. A relationship between NMP22 level in urine, GST level in blood and NAT2 genotype was observed. Also the isoenzyme GST-π in urine seems useful as a marker of BC.

Catalytic properties and heat stabilities of novel recombinant human N-acetyltransferase 2 allozymes support existence of genetic heterogeneity within the slow acetylator phenotype.

Human N-acetyltransferase 2 (NAT2) catalyzes the N-acetylation of numerous aromatic amine drugs such as sulfamethazine (SMZ) and hydrazine drugs such as isoniazid (INH). NAT2 also catalyzes the N-acetylation of aromatic amine carcinogens such as 2-aminofluorene and the O- and N,O-acetylation of aromatic amine and heterocyclic amine metabolites. Genetic polymorphism in NAT2 modifies drug efficacy and toxicity as well as cancer risk. Acetyltransferase catalytic activities and heat stability associated with six novel NAT2 haplotypes (NAT2*6C, NAT2*14C, NAT2*14D, NAT2*14E, NAT2*17, and NAT2*18) were compared with that of the reference NAT2*4 haplotype following recombinant expression in Escherichia coli. N-acetyltransferase activities towards SMZ and INH were significantly (p<0.0001) lower when catalyzed by the novel recombinant human NAT2 allozymes compared to NAT2 4. SMZ and INH N-acetyltransferase activities catalyzed by NAT2 14C and NAT2 14D were significantly lower (p<0.001) than catalyzed by NAT2 6C and NAT2 14E. N-Acetylation catalyzed by recombinant human NAT2 17 was over several hundred-fold lower than by recombinant NAT2 4 precluding measurement of its kinetic or heat inactivation constants. Similar results were observed for the O-acetylation of N-hydroxy-2-aminofluorene and N-hydroxy-2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine and the intramolecular N,O-acetylation of N-hydroxy-N-acetyl-2-aminofluorene. The apparent V max of the novel recombinant NAT2 allozymes NAT2 6C, NAT2 14C, NAT2 14D, and NAT2 14E towards AF, 4-aminobiphenyl (ABP), and 3,2'-dimethyl-4-aminobiphenyl (DMABP) were each significantly (p<0.001) lower while their apparent K m values did not differ significantly (p>0.05) from recombinant NAT2 4. The apparent V max catalyzed by NAT2 14C and NAT2 14D were significantly lower (p<0.05) than the apparent V max catalyzed by NAT2 6C and NAT2 14E towards AF, ABP, and DMABP. Heat inactivation rate constants for recombinant human NAT2 14C, 14D, 14E, and 18 were significantly (p<0.05) higher than NAT2 4. These results provide further evidence of genetic heterogeneity within the NAT2 slow acetylator phenotype.

Genetic heterogeneity among slow acetylator N-acetyltransferase 2 phenotypes in cryopreserved human hepatocytes.

Genetic polymorphisms in human N-acetyltransferase 2 (NAT2) modify the metabolism of numerous drugs and carcinogens. These genetic polymorphisms modify both drug efficacy and toxicity and cancer risk associated with carcinogen exposure. Previous studies have suggested phenotypic heterogeneity among different NAT2 slow acetylator genotypes. NAT2 phenotype was investigated in vitro and in situ in samples of human hepatocytes obtained from various NAT2 slow and intermediate NAT2 acetylator genotypes. NAT2 gene dose response (NAT2*5B/*5B>NAT2*5B/*6A>NAT2*6A/*6A) was observed towards the N-acetylation of the NAT2-specific drug sulfamethazine by human hepatocytes both in vitro and in situ. N-acetylation of 4-aminobiphenyl, an arylamine carcinogen substrate for both N-acetyltransferase 1 and NAT2, showed the same trend both in vitro and in situ although the differences were not significant (p>0.05). The N-acetylation of the N-acetyltransferase 1-specific substrate p-aminobenzoic acid did not follow this trend. In comparisons of NAT2 intermediate acetylator genotypes, differences in N-acetylation between NAT2*4/*5B and NAT2*4/*6B hepatocytes were not observed in vitro or in situ towards any of these substrates. These results further support phenotypic heterogeneity among NAT2 slow acetylator genotypes, consistent with differential risks of drug failure or toxicity and cancer associated with carcinogen exposure.

High frequency of NAT2 slow acetylator alleles in the Malay population of Indonesia: an awareness to the anti-tuberculosis drug induced liver injury and cancer

Background: Arylamine N-acetyltransferase 2 (NAT2) polymorphism was previously reported to have association with the risk of drug toxicities and the development of various diseases. Previous research on the Indonesian population, especially Javanese and Sundanese, showed that there were 33% NAT2 slow acetylator phenotype. The aim of this study was to map the NAT2 variation in the Malay ethnic to gain a deeper insight into NAT2 haplotypic composition in this ethnic.Methods: 50 healthy samples from the Indonesian Malay ethnic were obtained. They were interviewed about their ethnic backgrounds for the last three generations. DNA was extracted from peripheral blood and NAT2 genotyping was done using the PCR direct Sequencing. Data were compiled according to the genotype and allele frequencies estimated from the observed numbers of each specific allele. Haplotype reconstruction was performed using PHASE v2.1.1 software.Results: We found 7 haplotypes consisting of 6 SNPs and 14 NAT2 genotype variations in Indonesian Malay population. The most frequent allele was NAT2*6A (38%) which was classified as a slow acetylator allele. According to bimodal distribution, the predicted phenotype of the Malay population was composed of 62% rapid acetylator and 38% slow acetylator. According to trimodal distribution, the predicted phenotypes for rapid, intermediate and slow acetylators were 10%, 52% and 38% respectively.Conclusion: Our result indicates the presence of the allelic distribution and revealed the most frequent acetylator status and phenotype for the Indonesian Malay population. The result of this study will be helpful for future epidemiological or clinical studies and for understanding the genetic basis of acetylation polymorphism in Indonesia.

Polymorphisms of xenobiotic metabolizing enzymes in bladder cancer patients of the Semmelweis University Budapest, Hungary

ABSTRACTPolymorphic xenobiotic metabolizing enzymes such as N-acetyltransferase 2 (NAT2) or glutathione S-transferase M1 (GSTM1) are known to modulate bladder cancer risk. As no apparent data were available from Hungary, a former member of the eastern European economic organization, a study was performed in Budapest. In total, 182 bladder cancer cases and 78 cancer-free controls were investigated by questionnaire. Genotypes of NAT2, GSTM1, GSTT1, rs1058396 and rs17674580 were determined by standard methods. Current smokers’ crude odds ratio (OR) (3.43) and former smokers crude OR (2.36) displayed a significantly increased bladder cancer risk. The risk rose by a factor of 1.56 per 10 pack years. Exposure to fumes was associated with an elevated bladder cancer risk (23% cases, 13% controls). Sixty-four % of the cases and 59% of controls were slow NAT2 acetylators. It was not possible to establish a particular impact of NAT2*6A and *7B genotypes (15 cases, 8%, 5 controls, 7%). GSTT1 exerted no marked influence on bladder cancer (negative 21% cases vs. 22% controls). The portion of GSTM1 negative bladder cancer patients was increased (63% cases vs. 54% controls). The SLC14A1 SNPs rs1058396[AG/GG] and the nearby rs17674580[CT/TT] occurred more frequently in cases (79% and 68%) than controls (77% and 55%). The portion of GSTM1 negative bladder cancer patients is comparable with portions reported from other industrialized areas like Lutherstadt Wittenberg/Germany (58%), Dortmund/Germany (70%), Brescia/Italy (66%) or an occupational case-control series in Germany (56%). Data indicate that GSTM1 is a susceptibility factor for environmentally triggered bladder cancer rather than for smoking-mediated bladder cancer.

Distribution and Role of N-acetyltransferase 2 Genetic Polymorphisms in Bladder Cancer Risk in a Lebanese Population

Background:In Lebanon, bladder cancer (BC) has an unusually high prevalence. Individuals who are exposed to aromatic amines from smoking or certain occupations and carrying the slow N-acetyl transferase 2 (NAT2) acetylator’ phenotype may be at a higher risk.Methods:Data and DNA from 115 Lebanese BC cases and 306 controls were examined. Ten NAT2 single nucleotide polymorphisms were genotyped, seven of which were then included in haplotype and phenotype analysis.Results:BC patients were more likely to be males (87.8% vs. 54.9%) and current smokers (60.9% vs. 26.5%) when compared to controls. In both groups, most participants had the slow NAT2 acetylator phenotype (66.1% of BC cases vs 62.7% of controls; P=0.302) with the NAT2*5B and *6A haplotypes being the most common. The odds ratio (95%CI) of having BC among slow NAT2 acetylators was 1.157 (0.738-1.815) and remained non-significant after adjustment [1.097 (0.666-1.806)]. Sensitivity analysis with a subgroup of 113 cases and 84 controls for which occupational history was available revealed a statistically significant association between slow NAT2 acetylators and BC in females only. The sample size was however very small and the CI quite wide.Conclusions:This is the first study to evaluate the distribution of NAT2 haplotypes and their potential role in BC in a Lebanese population. The absence of any significant association may be due to the relatively small sample size, the unavailability of matching by gender, and the lack of evaluation of genetic interactions with extent of active and passive smoking, exposure to environmental pollutants, diet, and other genes. The potential association limited to females needs further evaluation.

Association between N-Acetyltransferase 2 Polymorphism and Bladder Cancer Risk: a Meta-Analysis in a Single Ethnic Group.

Many studies have evaluated the correlation between N-acetyltransferase 2 (NAT2) slow acetylation genotype and bladder cancer risk. However, the results are inconsistent and remain to be confirmed in each ethnic group. To assess the effects of NAT2 acetylation status on the risk of bladder cancer in the Chinese population, a meta-analysis was performed. Studies were identified using PubMed and Chinese databases through February 2016. The associations were assessed with pooled odds ratios (ORs) and 95% confidence intervals (CIs). This meta-analysis included 10 studies with 896 bladder cancer cases and 1188 controls. In the overall analysis, NAT2 slow acetylation phenotype was significantly associated with an increased risk of bladder cancer in the Chinese population (OR = 1.68, 95% CI = 1.11 - 2.53). In the subgroup analyses by geographic areas and sources of controls, significant risk was found in Mainland China (OR = 1.83, 95% CI = 1.04 - 3.20) and hospitalbased studies (OR = 1.74, 95% CI = 1.27 - 2.38), but not in Taiwan China. This meta-analysis suggested that the NAT2 slow acetylation genotype is associated with an increased bladder cancer risk in Chinese individuals.

NAT2 slow acetylator associated with anti-tuberculosis drug-induced liver injury in Thai patients.

Anti-tuberculosis drug-induced liver injury (AT-DILI) is one of the most common forms of drug-induced liver injury (DILI) in high tuberculosis (TB) burden countries. Among anti-tuberculosis drugs, isoniazid is the main cause of hepatotoxicity in patients with AT-DILI. To investigate the association of AT-DILI with N-acetyltransferase 2 (NAT2) genotype status in Thai TB patients. We enrolled 53 patients diagnosed with AT-DILI and 85 patients who tolerated anti-tuberculosis treatment as controls. Acetylator status was determined based on the inferred NAT2 haplotypes from four common single-nucleotide polymorphisms (SNPs) in Thais using Sanger sequencing. Phenotype frequencies of the NAT2 acetylator in AT-DILI patients were respectively 71.7%, 22.6% and 5.7% for slow, intermediate and rapid acetylators. Among slow, intermediate, and rapid acetylators in treatment tolerant controls, phenotype frequencies were respectively 22.4%, 62.4% and 15.3%. Slow NAT2 acetylators demonstrated a significant association with risk of AT-DILI. The odds ratio of comparing slow NAT2 acetylator in DILI patients and tolerance was 8.80 (95%CI 4.01-19.31, P = 1.53 × 10-8). Slow acetylator status in the NAT2 genotype is a significant risk factor for DILI in Thai patients with TB. This evidence provides confirmatory data in support of the role of NAT2 in AT-DILI in the Thai population.

Development of a prediction system for anti-tuberculosis drug-induced liver injury in Japanese patients.

Drug-induced liver injury (DILI) is a common adverse drug reaction in patients receiving antituberculosis (anti-TB) treatment. Among the anti-TB agents, isoniazid (INH) is the primary drug that causes hepatotoxicity in TB patients with DILI. Previous reports in several populations have consistently demonstrated an association between polymorphisms in the N-acetyltransferase 2 (NAT2) gene, which is responsible for INH hepatic metabolism, and a risk of DILI in TB patients. In this study, the genetic and baseline clinical data from 366 Japanese patients with TB (73 patients with DILI and 293 without DILI) were used to develop a system to predict DILI risk due to anti-TB agents. The distribution of the NAT2 acetylator status among the TB patients with DILI was 31 (42.5%), 29 (39.7%), and 13 (17.8%) for rapid, intermediate, and slow acetylators, respectively. A significant association was observed between NAT2 slow acetylators and DILI risk (odds ratio 4.32, 95% confidence interval 1.93–9.66, P value=5.56×10−4). A logistic regression model based on age and NAT2 genotype revealed that the area under the curve for the receiver-operating characteristic curve was 0.717. The findings demonstrated that slow NAT2 acetylator status is a significant predictor of the risk of DILI by anti-TB agents, and a personalized anti-TB treatment approach may aid in making treatment decisions and reducing the incidence of DILI.

Association of N-acetyltransferase-2 polymorphism with an increased risk of coronary heart disease in a Chinese population.

We investigated the possible correlations between N-acetyltransferase-2 (NAT2) gene polymorphisms and the risk of coronary heart disease (CHD). CHD patients (113) and healthy controls (118) were enrolled from the First People's Hospital of Yuhang between January 2013 and June 2014. The patients were divided into mild CHD (N = 72) and severe CHD (N = 41) subgroups. DNA samples were extracted and the distributions of NAT2 polymorphisms were examined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Clinical characteristic indexes of severe CHD patients were also examined for relevant statistical analysis. WT, M1, M2, and M3 alleles were observed in both case and control groups. PCR-RFLP identified a wild-type homozygote, WT/WT; a mutant heterozygote, WT/Mx; and a mutant homozygote, Mx/Mx (x = 1, 2, and 3) variant of the NAT2 genotype. Mx/Mx differed significantly between case and control groups (P < 0.05); the frequencies of all four alleles did not differ significantly between case and control groups (P > 0.05). Slow acetylator genotype frequencies were notably higher in the case group than in the control group (P < 0.05). Individuals with the slow acetylator genotype were at 1.97-times higher risk of CHD and also displayed higher triglyceride and lower high-density lipoprotein cholesterol levels than those with the rapid acetylator genotype (P < 0.05). Therefore, the NAT2 polymorphism was believed to be associated with increased risk of CHD, with the NAT2 slow acetylator genotype serving as a risk factor for severe CHD in a Chinese population.

Susceptibility of N-acetyltransferase 2 slow acetylators to antituberculosis drug-induced liver injury: a meta-analysis.

This study aimed to evaluate the association between N-acetyltransferase 2 (NAT2) gene polymorphisms and the risk of antituberculosis drug-induced liver injury (ATLI). A meta-analysis was performed including 27 studies with 1289 cases and 5462 controls. Odds ratio with 95% CI was used to evaluate the strength of association. Our meta-analysis found that NAT2 slow acetylators were associated with increased risk of ATLI compared with fast and intermediate acetylators when standard dose of isoniazid was administrated (odds ratio: 3.08; 95% CI: 2.29-4.15). Individuals with NAT2 slow acetylators may have increased risk of ATLI when standard dose of isoniazid was used. Detection of NAT2 genotype may benefit to the prevention of ATLI.

N-Acetyltransferase 2 (NAT2) genetic variation and the susceptibility to noncardiac gastric adenocarcinoma in Taiwan

BackgroundN-Acetyltransferase (NAT) is an important enzyme with the capacity to metabolize carcinogenic aromatic amines. However, it remains controversial whether the encoded functional NAT2 genetic polymorphism is related to the risk of gastric adenocarcinoma (GA). The aim of this study was to evaluate the association between NAT2 genetic variation and gastric adenocarcinoma (GA), with special reference to the gastric noncardiac adenocarcinoma (GNA). MethodsPeripheral white blood cell DNA from 368 GA patients and 368 age- and sex-matched controls were genotyped for NAT2 by a polymerase chain reaction method. The lifestyle habits of the participants were assessed using a semiquantitative food–frequency questionnaire. NAT2 genotype, interaction with lifestyle habits, and the risk of GA and GNA were analyzed by logistic regression. ResultsGA patients were more likely to have a smoking habit, ate more salted foods, and consumed more well-done meat than the controls. There was no association between the NAT2 genotypes and susceptibility to GA. However, if patients with gastric cardiac adenocarcinoma (GCA; n = 42) were excluded, the NAT2 slow acetylators (without rapid acetylator allele) had a higher risk of GA than intermediate and rapid acetylators (odds ratio = 1.53; 95% confidence interval, 1.05–2.23, p = 0.027). In addition, there was a synergic effect of NAT2 slow acetylator and well-done meat intake to the development of GNA (odds ratio = 3.83; 95% confidence interval, 1.68–8.76, p = 0.001). ConclusionNAT2 slow acetylators have a higher risk of GNA than intermediate and rapid acetylators have in a Taiwanese population. The intake of well-done meat, an additive to the acetylator status, may contribute to the incidence of gastric carcinogenesis.

Correlation between NAT2 gene polymorphism and cirrhotic portal hypertension in the Chinese population.

Our study aims to discuss the correlation between N-acetyltransferase 2 (NAT2) gene polymorphism and cirrhotic portal hypertension in the Chinese population for the purpose of exploring the functional significance of NAT2 gene polymorphism. From June 2010 to February 2014, a total of 212 posthepatitis B cirrhosis patients (the observation group) from the affiliated Shandong Province-owned Hospital of Shandong University diagnosed by needle biopsy of the liver, B ultrasound, or surgical operation were recruited. These 212 patients were divided into a cirrhotic portal hypertension group (PHT(+) group) (130 patients) and a simple liver cirrhosis (LC) group (PHT(-) group) (82 patients), and 172 healthy blood donors were enrolled into the control group. The polymerase chain reaction-restriction fragment length polymorphism method was adopted to detect NAT2 gene polymorphism and some related statistical analysis. In these 212 patients, four mutation alleles in the NAT2 gene (WT, M1, M2, and M3) were detected. The frequency of patients carrying NAT2 slow acetylator genotype in the observation group was higher than that in the control group, but there was no significant difference (p>0.05). However, there was a significant difference in the NAT2 slow acetylator genotype frequency between the PHT(+) group and the control group (p<0.05). The risk for the occurrence of PHT in NAT2 slow acetylator genotype carriers was more frequent than that in NAT2 rapid acetylator genotype carriers. In addition, the diameters of the portal vein and splenic vein as well as spleen thickness in NAT2 rapid acetylator genotype were obviously bigger than that in the NAT2 slow acetylator genotype. Our study provided empirical evidence that NAT2 gene polymorphism may be correlated to the formation of cirrhotic portal hypertension, and it might be used as a potential biomarker for genetic susceptibility to PHT in Chinese population.

Association between N-acetyltransferase 2 polymorphisms and pancreatic cancer risk: a meta-analysis.

N-acetyltransferase 2 (NAT2) is an essential phase II enzyme in the metabolism of aromatic and heterocyclic amines and of hydrazines. NAT2 activity can be divided into three phenotypes: rapid, intermediate, and slow. Studies identifying an association between NAT2 polymorphism and the risk of pancreatic cancer have shown conflicting results. In order to assess this relationship comprehensively, we performed a meta-analysis that involved 1607 patients with pancreatic cancer and 1682 controls from six studies, which were selected from a group of ten, identified by a search of PubMed and Embase databases up to July 2014. Relative risks (RRs) with 95% confidence intervals (CIs) were used to evaluate the relationships. In the overall analysis, no significant associations between NAT2 rapid acetylation genotypes and pancreatic cancer risk (RR = 0.93, 95%CI = 0.73-1.19) were found; however, the results showed significant heterogeneity (I2 = 55.0%). The results from subgroup analysis suggested that the rapid genotypes might decrease the risk of pancreatic cancer (RR = 0.56, 95%CI = 0.38-0.84) in Turkey, although the association was not significant in the United States population (RR = 0.97, 95%CI = 0.71-1.34) or in the multi-center studies (RR = 1.10, 95%CI = 0.90-1.34). Analysis of the slow acetylation genotypes demonstrated the converse outcomes. In conclusion, the results of our study suggested that the NAT2 slow acetylation genotypes might increase the susceptibility to pancreatic cancer in Europe but that these have no significant effects in the United States and multi-center populations.

Arylamine N-acetyltransferase polymorphisms in Han Chinese patients with ankylosing spondylitis and their correlation to the adverse drug reactions to sulfasalazine.

BackgroundPolymorphisms of Arylamine N-acetyltransferase (NAT) that contribute to diverse susceptibilities of some autoimmune diseases are also linked to the metabolism of several drugs including sulfasalazine (SSZ). The aim of this study was to investigate the distribution of NAT polymorphisms in Han Chinese patients with ankylosing spondylitis (AS) and their correlation to sulfasalazine-induced adverse drug reactions (ADRs).MethodsArylamine N-acetyltransferase 1 (NAT1) and arylamine N-acetyltransferase 2 (NAT2) genotypes were determined in 266 AS patients who received SSZ treatment and 280 healthy controls. The correlation between NAT polymorphisms and SSZ-induced ADRs was analyzed.ResultsThe co-occurrence frequency of NAT2 fast acetylator genotype and NAT1*10/NAT1*10 genotype was lower in AS patients than in controls. No positive correlations were detected between NAT polymorphisms and AS clinical features. The prevalence of SSZ-induced ADRs and drug withdrawal was 9.4% and 7.1%, respectively. The frequencies of overall ADRs, dose-related ADRs, and termination of drug treatment because of intolerance were higher in the NAT2 slow acetylator genotype carriers than in the fast-type carriers and in those with co-existence of NAT1 and NAT2 slow acetylator genotypes. Furthermore, the ADRs emerged earlier in the AS cases carrying both NAT1 and NAT2 slow acetylator genotypes.ConclusionsThe prevalence of co-occurring NAT2 fast acetylator genotype and NAT1*10/NAT1*10 genotype was lower in AS patients than in controls. The NAT2 slow acetylator genotype and co-existing NAT1 and NAT2 slow acetylator genotypes appear to be associated with higher risks of SSZ-induced ADRs.

Molecular Approach for Assessing the Risk Factors for Anti-tubercular Therapy-Induced Hepatotoxicity

Introduction: The present study was designed to study the role of genetic risk factors like N-acetyl transferase2 (NAT2) polymorphism and glutathione S-transferase (GST T1 and M1) mutations for increasing the susceptibility of anti tubercular therapy (ATT)-induced hepatotoxicity. Methods: Forty pulmonary tuberculosis patients who developed hepatotoxicity while on treatment with antituberculosis drug (ATD) were included. Sixty pulmonary tuberculosis patients without clinical symptoms and biochemical evidence of liver dysfunction, who were on antitubercular treatment, were included as controls. NAT2 genotyping was performed by generation of 895 bp intronless NAT2 PCR fragment. NAT2 genotyping was carried out by PCR-RFLP at 3 major polymorphic sites of gene coding for T481C (rs1799929, NAT2*5), G509A (rs1799930, NAT2*6), and G587A (rs1799931, NAT2*7). Genotyping of GST M1 and GST T1 genes was carried out by multiplex polymerase chain reaction protocol. Results: Out of the 40 patients of ATT-induced hepatitis, 67.50% were slow acetylators as compared to 35% in the control group. The risk of anti-TB DIH occurrence was significantly higher in slow acetylators than in rapid/intermediate acetylator (56.25% vs. 25%, p value 0.05). Slow acetylator phenotype was found to be a risk factor for anti-TB drug-induced hepatitis having an odds ratio of 3.85 (95% confidence interval [CI] 1.68-8.84; p value 0.02). The GSTM1 null mutation was found in 19 out of 40 cases (47.5%) compared to 15 out of 60 controls (25.0%). Subjects with GSTM1 null genotype were found to be at a 2.72 times risk of developing ATT induced hepatitis than those who had GSTM1 gene (p value 0.02). Similarly, the frequency of GSTT1 null mutation was found to be 32.50% in the ATT-induced hepatitis group as compared to 13.33% in the control group and GSTT1 null genotype, was also found to be an independent risk factor with an odds ratio of 3.12 (95% CI 1.18-8.22; p value- 0.02). It was also observed that presence of GSTM1 and GSTT1 null genotype together increased the likelihood of developing ATT induced hepatitis to up to 17 times (p value 0.002). Conclusion: This study could establish a positive co-relation between NAT2 slow acetylators, GSTM1 null mutation, GSTT1 null mutation, and ATT induced hepatitis. Thus, it will be prudent on the part of the clinicians to look for the above risk factors while treating Koch’s patients with anti-tubercular therapy.

N-acetyltransferase 2 (NAT2) genotype as a risk factor for development of drug-induced liver injury relating to antituberculosis drug treatment in a mixed-ethnicity patient group.

This study aims to assess whether NAT2 genotype affects susceptibility to moderate to severe liver injury in patients undergoing drug treatment for tuberculosis with isoniazid-containing regimens. Twenty-six patients of European or South Asian ethnicity, who had suffered liver injury during treatment with isoniazid-containing drug regimens and 101 ethnically matched controls were genotyped for the NAT2*5, NAT2*6, and NAT2*7 alleles. Genotyping for additional polymorphisms in the NAT gene region was also performed on 20 of the 26 cases. NAT2 genotype frequency between cases and controls was compared. NAT2 genotypes predicting a slow acetylator phenotype were found to be associated with an increased risk of isoniazid-related liver injury (odds ratio (OR) = 4.25 (95% confidence interval (CI), 1.36-13.22); p = 0.012) with 85% of the cases being slow acetylators compared with 56% of the controls. There was no evidence for an increased risk for the slow acetylator genotype in patients with the most severe cases of liver injury, who underwent liver transplantation. The NAT2 slow acetylator genotype appears to be a significant risk factor for moderate and severe drug- induced liver injury. However, the overall effect size is modest and generally in line with effects described previously for this genotype in milder drug-induced liver injury. Additional genetic risk factors may also contribute.

Polymorphisms in CYP2E1, GSTM1 and GSTT1 and anti-tuberculosis drug-induced hepatotoxicity

Anti-tuberculosis drug-induced hepatitis (ATD- induced hepatitis) has been linked to polymorphisms in genes encoding drug metabolizing enzymes. N-acetyltransferase 2 (NAT2), cytochrome P450 2E1 (CYP2E1) and glutathione S-transferase (loci GSTM1 and GSTT1) are involved in the metabolism of isoniazid, the most toxic drug for the treatment of tuberculosis (TB). This study was designed to determine the frequency and to evaluate whether polymorphisms at CYP2E1, GSTM1 and GSTT1 genes are associated with drug response, as well as to identify clinical risk factors for ATD-induced hepatitis. A total of 245 Brazilian patients undergoing treatment for TB were genotyped using polymerase chain reaction and restriction fragment length polymorphism and sequencing methods. The frequencies of the CYP2E1 polymorphic alleles RsaI, PstI and DraI are 8%, 8.5% and 12%, respectively. GSTM1 and GSTT1 genes are deleted in 42.9% and 12.4% of the population, respectively. Fifteen patients (6.1%) developed hepatotoxicity. Clinical (HIV, female sex and extrapulmonary TB) and genetic characteristics (CYP2E1 without any mutations, having NAT2 slow acetylator profile) are at higher risk of developing ATD-induced hepatitis in this population. Genotyping for GSTM1 and GSTT1 showed no influence on drug response.

The association between CYP2E1 polymorphisms and hepatotoxicity due to anti-tuberculosis drugs: A meta-analysis

BackgroundAlthough there have been previous studies on the potential association between cytochrome P450 2E1 (CYP2E1) polymorphisms and the risk of anti-tuberculosis drug-induced hepatotoxicity (ATDH), the results have generally been controversial. MethodsWe searched Medline/PubMed, EMBASE, Web of Science, and the Cochrane Library using the following key words: cytochrome P450 2E1, CYP2E1, polymorphism, tuberculosis and TB. The strength of the association between the CYP2E1 PstI/RsaI and DraI polymorphism and ATDH risk as measured by odds ratios (OR) with 95% confidence intervals (CIs) was studied. ResultsCompared with the wild genotype (c1/c1), the OR of ATDH was 1.41 (95% CI: 1.1–1.82, P=0.007) for the PstI/RsaI polymorphism, and 0.78 (95% CI: 0.51–1.18, P=0.23) for the DraI polymorphism. Compared with individuals with N-acetyltransferase 2 (NAT2) fast or intermediate acetylator genotype and c1/c1 genotype patients who were NAT2 slow acetylators and carried the high activity CYP2E1 c1/c1 genotype had higher risk for ATDH (OR=3.10, P<0.0001). ConclusionThe present meta-analysis indicates that the CYP2E1 c1/c1 genotype may be a risk factor for ATDH, and the concomitant presence of the slow acetylator NAT2 genotype may further increase this risk.

N-acetyltransferase 2 Phenotype, Occupation, and Bladder Cancer Risk: Results from the EPIC Cohort

An association between N-acetyltransferase 2 (NAT2) slow acetylation and bladder cancer has been consistently observed in epidemiologic studies. However, evidence has been mainly derived from case-control studies and was sparse from cohort studies. We evaluated the association between NAT2 slow acetylation and bladder cancer in a case-control study nested in the European Prospective Investigation into Cancer and Nutrition. Exposure to aromatic amines and polycyclic aromatic hydrocarbons (PAH) could be assessed for 754 cases and 833 controls for whom occupational information was documented. A semiquantitative job-exposure matrix was applied to at-risk occupations to estimate the exposure as low, medium, or high based on tertiles of the distribution of the exposure score in controls. Using a comprehensive genotyping, NAT2 acetylation status could be categorized from 6-single-nucleotide polymorphism genotypes as slow or fast in 607 cases and 695 controls with DNA from archived blood samples. Occupational exposure to aromatic amines and PAH was associated with an increased bladder cancer risk [upper tertile of the distribution of the exposure score: OR = 1.37; 95% confidence interval (CI), 1.02-1.84, and OR = 1.50; 95% CI, 1.09-2.05, respectively]. NAT2 slow acetylation did not modify these risk estimates and was not itself associated with bladder cancer risk (OR = 1.02; 95% CI, 0.81-1.29). These findings confirm established or suspected occupational risk factors but not the anticipated role of NAT2 slow acetylation in bladder cancer. No interaction was detected between NAT2 and any exposure of interest, including smoking. Genetic testing for NAT2 would be inappropriate in occupational settings.