Polymorphic N-acetyltransferase Research Articles

The N‐Acetyltransferase 2 Polymorphism and Susceptibility to Inflammatory Bowel Disease: A Case–Control Study

ABSTRACTThe enzyme N‐acetyltransferase 2 (NAT2) plays an important role in metabolism and detoxification of xenobiotics, including carcinogens and medications. We aimed to assess the contribution of the NAT2 polymorphism to susceptibility to inflammatory bowel disease (IBD) in the Polish population. The study involved 101 IBD patients and 100 healthy controls. The NAT2 gene mutations at positions 481T, 803G, 590A, and 857A were identified using the polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) technique on peripheral blood DNA samples. Carriers of the NAT2*5 allele had a greater chance of developing Crohn's disease (CD) (OR = 1.73, 95% CI 1.06–2.83). Also, the NAT2*4/5 genotype was more prevalent in CD patients (OR = 2.77, 95% CI 1.17–6.57). When compared to the control group, the prevalence of the NAT2*4/6 genotype in the IBD patient population was significantly lower (10.9% vs. 30.0%, p < 0.01). In the Polish population, polymorphism in the NAT2 gene may potentially alter susceptibility to IBD.

Association of Cytochrome P450 2E1 and N-Acetyltransferase 2 Genotypes with Serum Isoniazid Level and Anti-Tuberculosis Drug-Induced Hepatotoxicity: A Cross-Sectional Study.

Anti-tuberculosis drug-induced hepatotoxicity can result from genetic polymorphism of the isoniazid (INH) metabolizing enzyme. This study aimed to determine the effect of genetic polymorphism of N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1) genes on serum isoniazid level and drug-induced hepatotoxicity. A cross-sectional study was conducted on 120 patients (with and without hepatotoxicity) with pulmonary tuberculosis from June 2019 to April 2022 in Tehran (Iran). High-performance liquid chromatography was used to measure the serum concentration of INH and acetylisoniazid (AcINH). NAT2 and CYP2E1 genotypes were determined using polymerase chain reaction and restriction fragment length polymorphism methods. Data were analyzed using SPSS software (version 22.0) with independent two-sample t test, Chi square test, or Fisher's exact test. P<0.05 was considered statistically significant. A total of 40 patients showed hepatotoxicity. The risk of anti-tuberculosis drug-induced hepatotoxicity was significantly higher in patients who are slow acetylator (SA) phenotype than in rapid or intermediate acetylator (P<0.001). NAT2*4/*4 genotypes were not found in patients with hepatotoxicity. The frequency of NAT2*5 and NAT2*6 haplotypes and serum INH concentration was significantly higher in patients with hepatotoxicity than in those without (P=0.003, P<0.001, and P<0.001, respectively). NAT2*4 haplotype was correlated with protection against hepatotoxicity. A combination of SA and CYP2E1 C1/C1 genotype was significantly associated with hepatotoxicity (P<0.001). Hepatotoxicity in Iranian patients with tuberculosis was confirmed due to the presence of NAT2 SA polymorphism. Determining NAT2 and CYP2E1 genotypes and/or INH concentration can be a valuable tool to identify patients susceptible to hepatotoxicity.

TaqMan Genotyping Assay Method for Single Nucleotide Polymorphisms (SNPs) detection in promoter region of N-Acetyltransferase 2 (NAT2) gene

The N-acetyltransferase 2 (NAT2) polymorphism in coding region has been studies intensively. However, there are limited studies for promoter region of NAT2 gene. Several reported study showed that the promoter region polymorphism of NAT2 gene is genotyped by PCR-sequencing approach. In this paper, we describe TaqMan based assays for the NAT2 polymorphism genotyping in promoter region with following SNP: rs4646243 [T&gt;C], rs4646244 [T&gt;A], rs4646267 [A&gt;G], rs4345600 [A&gt;G], and rs4646246 [A&gt;G]. Our result showed a good separation cluster, trailing cluster and some mix cluster. TaqMan genotyping assay has shown a sensitivity and specificity to detect polymorphism in NAT2 promoter region.

N-acetyltransferase 2 genetic polymorphism modifies genotoxic and oxidative damage from new psychoactive substances.

The use of new psychoactive substances (NPS) as drugs of abuse is common and increasingly popular, particularly among youth and neglected communities. Recent studies have reported acute toxic effects from these chemicals; however, their long-term toxicity is unknown. Genetic differences between individuals likely affect the toxicity risk. Arylamine N-acetyltransferase 2 (NAT2) capacity differs among individuals due to genetic inheritance. The goal of the present study is to investigate the gene-environment interaction between NAT2 polymorphism and toxicity after exposure to these chemicals. We measured N-acetylation by human NAT1 and NAT2 and found that N-acetylation of NPS is carried out exclusively by NAT2. Differences in N-acetylation between NAT2*4 (reference allele) and NAT2*5B (common variant allele) were highly significant (p < 0.0001). Using DNA repair-deficient genetically engineered Chinese hamster ovary (CHO cells), expressing human CYP1A2 and either NAT2*4 or NAT2*5B, we measured the induction of DNA double-strand breaks ([Formula: see text]H2Ax) following treatment of the CHO cells with increasing concentrations of NPS. The induction of [Formula: see text]H2Ax showed a NAT2 allele-dependent response, higher in the NAT2*4 vs NAT2*5B alleles (p < 0.05). Induction of oxidative stress (ROS/RNS) was evaluated; we observed NAT2 allele-dependent response for all compounds in concentrations as low as 10 [Formula: see text]M, where NAT2*4 showed increased ROS/RNS vs NAT2*5B (p < 0.05). In summary, NPS are N-acetylated by NAT2 at rates higher in cells expressing NAT2*4 than NAT2*5B. Exposure to psychoactive chemicals results in genotoxic and oxidative damage that is modified by the NAT2 genetic polymorphism.

Differences in β-naphthylamine metabolism and toxicity in Chinese hamster ovary cell lines transfected with human CYP1A2 and NAT2*4, NAT2*5B or NAT2*7B N-acetyltransferase 2 haplotypes.

β-naphthylamine (BNA) is an important aromatic amine carcinogen. Current exposures derive primarily from cigarette smoking including e-cigarettes. Occupational and environmental exposure to BNA is associated with urinary bladder cancer which is the fourth most frequent cancer in the United States. N-acetyltransferase 2 (NAT2) is an important metabolizing enzyme for aromatic amines. Previous studies investigated mutagenicity and genotoxicity of BNA in bacteria and in rabbit or rat hepatocytes. However, the effects of human NAT2 genetic polymorphism on N-acetylation and genotoxicity induced by BNA still need to be clarified. We used nucleotide excision repair-deficient Chinese hamster ovary (CHO) cells that were stably transfected with human CYP1A2 and NAT2 alleles: NAT2*4 (reference allele), NAT2*5B (variant slow acetylator allele common in Europe) or NAT2*7B (variant slow acetylator allele common in Asia). BNA N-acetylation was measured both in vitro and in situ via high-performance liquid chromatography (HPLC). Hypoxanthine phosphoribosyl transferase (HPRT) mutations, double-strand DNA breaks, and reactive oxygen species (ROS) were measured as indices of toxicity. NAT2*4 cells showed significantly higher BNA N-acetylation rates followed by NAT2*7B and NAT2*5B. BNA caused concentration-dependent increases in DNA damage and ROS levels. NAT2*7B showed significantly higher levels of HPRT mutants, DNA damage and ROS than NAT2*5B (p < 0.001, p < 0.0001, p < 0.0001 respectively) although both are slow alleles. Our findings suggest that BNA N-acetylation and toxicity are modified by NAT2 polymorphism. Furthermore, they confirm heterogeneity among slow acetylator alleles for BNA metabolism and toxicity supporting differential risk for individuals carrying NAT2*7B allele.

NAT2 and CYP2E1 polymorphisms and antituberculosis drug-induced hepatotoxicity in Peruvian patients.

BackgroundIn Peru, 32,970 people were diagnosed with tuberculosis (TB) in 2019. Although TB treatment is effective, 3.4%–13% is associated with significant adverse drug reactions (ADR), considering drug‐induced liver injury (DILI) as the most prevalent. Among the first‐line anti‐TB drugs, isoniazid (INH) is primarily responsible for the occurrence of DILI. INH is metabolized in the liver by the enzymes N‐acetyltransferase‐2 (NAT2) and Cytochrome P450 2E1 (CYP2E1). Based on the previous studies, we hypothesized that the interactions between slow CYP2E1 genotype and NAT2 slow acetylators will induce DILI in TB patients.MethodsIn this cross‐sectional study, all 377 participants completed their anti‐TB treatment, and we genotyped SNPs: rs1041983, rs1801280, rs1799929, rs1799930, rs1208, and rs1799931 for NAT2 and rs3813867 and rs2031920 for CYP2E1.ResultsWe found that rapid, intermediate, and slow NAT2 acetylator were 15%, 38%, and 47%, respectively, in the general population. Intermediate NAT2 acetylator is the least prevalent among patients with adverse reactions (p = 0.024). We did not confirm our hypothesis, however, we found that the combination of intermediate NAT2 acetylators and CYP2E1 c1/c1 genotype significantly protected (OR = 0.16; p = 0.049) against the development of DILI in our population.ConclusionWe propose that the presence of NAT2 intermediate and CYP2E1 c1/c1 genotype could help in therapeutic drug monitoring, and optimize its therapeutic benefits while minimizing its risk for side effects or toxicity.

Relevance of gene polymorphisms of NAT2 and NR1I2 to anti-tuberculosis drug-induced hepatotoxicity

The recommended treatment regimen for tuberculosis is a combination of agents with antitubercular activity, during which hepatotoxicity is one of the most common side effects. In addition to the N-acetyltransferase 2 (NAT2) genotype, rs3814055 in nuclear receptor subfamily 1, group I, member 2 (NR1I2) has been demonstrated to be associated with anti-tuberculosis drug-induced hepatotoxicity (ATDH), but previous results have been inconsistent. A retrospective nested hospital-based case–control study was performed to investigate the association between genetic polymorphisms and the risk of ATDH. Fifteen genetic variants (13 SNPs and two null genotypes) in cytochrome P450 2E1, NR1I2, UDP-glucuronosyltransferase 1A1, NAT2, superoxide dismutase 1, superoxide dismutase 2, and glutathione S-transferases (GSTT1, GSTM1, GSTP1) were genotyped. Odds ratios with 95% confidence intervals were calculated with drug doses, body mass index comorbidity of diabetes mellitus, and baseline alanine transaminase value as covariates. Conditional logistic regression demonstrated that the NAT2 slow acetylation genotype and the T allele of rs3814055 in NR1I2 may contribute to susceptibility to ATDH. Stratified association analysis demonstrated that in NAT2 non-slow acetylators, the T allele of rs3814055 was a risk factor for ATDH, whereas the T allele did not increase the susceptibility to ATDH in slow acetylators.

560G>A (rs4986782) (R187Q) Single Nucleotide Polymorphism in Arylamine N-Acetyltransferase 1 Increases Affinity for the Aromatic Amine Carcinogens 4-Aminobiphenyl and N-Hydroxy-4-Aminobiphenyl: Implications for Cancer Risk Assessment.

Human arylamine N-acetyltransferase 1 (NAT1) catalyzes the N-acetylation of arylamine carcinogens such as 4-aminobiphenyl (ABP), and following N-hydroxylation, the O-acetylation of N-hydroxy-arylamine carcinogens such as N-hydroxy-ABP (N-OH-ABP). Genetic polymorphisms in NAT1 are linked to cancer susceptibility following exposures. The effects of individual single nucleotide polymorphisms (SNPs) in the NAT1 coding exon on Michaelis-Menten kinetic constants was assessed for ABP N-acetyltransferase and N-OH-ABP O-acetyltransferase activity following transfection of human NAT1 into COS-1 cells (SV40-transformed African green monkey kidney cells). NAT1 coding region SNPs 97C > T (rs56318881) (R33stop), 190C > T (rs56379106) (R64W), 559C > T (rs5030839) (R187stop) and 752A > T (rs56172717) (D251V) reduced ABP N- acetyltransferase and N-OH-ABP O-acetyltransferase activity below detection. 21T > G (rs4986992) (synonymous), 402T > C (rs146727732) (synonymous), 445G > A (rs4987076) (V149I), 613A > G (rs72554609) (M205V) and 640T > G (rs4986783) (S241A) did not significantly affect Vmax for ABP N-acetyltransferase or N-OH-ABP O-acetyltransferase. 781G > A (rs72554610) (E261K), and 787A > G (rs72554611) (I263V) slightly reduced ABP N-acetyltransferase and N-OH-ABP O-acetyltransferase activities whereas 560G > A (rs4986782) (R187Q) substantially and significantly reduced them. 560G > A (rs4986782) (R187Q) significantly reduced the apparent Km for ABP and N-OH-ABP a finding that was not observed with any of the other NAT1 SNPs tested. These findings suggest that the role of the 560G > A (rs4986782) (R187Q) SNP cancer risk assessment may be modified by exposure level to aromatic amine carcinogens such as ABP.

Ontogeny of Pediatric Pharmacogenetics: Celebrating the Past and Vision for the Future.

Ontogeny of Pediatric Pharmacogenetics: Celebrating the Past and Vision for the Future.

Correlation between Nonsynonymous A803G Polymorphism of N-acetyltransferase 2 Gene and Impaired Glucose Homeostasis in Egyptian Obese Children and Adolescents

Background: Two thirds of the world's populations live in countries where obesity-related illness is a significant cause of death. There is a considerable increase in adult obesity and there is good evidence that more children are also becoming obese especially over the last 30 years period. Objective: To assess A803G polymorphism in the NAT2 gene in Egyptian obese children and adolescents and to detect the relation between this gene mutation and development of impaired glucose homeostasis in them. Patients and methods: 100 children and Adolescents were investigated in the study. They were divided into 2 groups according to their HbA1c: 50diagnosed as pre-diabetic obese were enrolled as group (1) and 50 diagnosed as non-diabetic obese were enrolled as group (2). Results: correlation between HbA1c and HOMAIR showed that HbA1c was statistically significantly positively correlated with weight, waist circumference, systolic and diastolic blood pressures, HOMAIR, total cholesterol and LDL. While, HbA1c was statistically significantly negatively correlated with HDL and BMI-SDS, with no statistically significant correlations with other variables among Group 1. HOMA-IR was statistically significantly positively correlated with weight, waist circumference and systolic and diastolic blood pressures. While, HOMAIR was statistically significantly negatively correlated with BMI-SDS among Group 1. HbA1c was statistically significantly positively correlated with weight and waist with no statistically significant correlation with other variables among Group 2. Conclusion: Egyptian obese children and adolescents who are carrying NAT2 A803 allele might be at a high risk of developing impaired glucose homeostasis and consequent increased future risk to develop diabetes mellitus type 2.

Genetic polymorphism of NAT1 in local Pakistani population

The present research project was designed to determine the genetic polymorphism of N-acetyltransferase 1 (NAT1), the acetylation status in the local Pakistani population because of the genetic polymorphism of drug-metabolizing enzymes constitutes an individual's susceptibility and toxicity for drugs. The normal health status of enrolled volunteers was ensured by their baselines hematological and biochemical studies like CBC, blood cell morphology, LFTs, RFTs Lipid profile and plasma proteins. The acetylation capacity was determined genotypically by PCR-based allele-specific amplification assay and restriction fragment length polymorphism (RFLP) for wild-type and variant alleles. The mutual concordance between the phenotypic and genotypic analysis was determined. The target population showed bimodal distribution based on genotyping. Almost 69% Pakistani local population was found to have fast acetylator alleles/genotype and 30% population with slow acetylator allele/genotype. The interethnic distributions of NAT1 alleles show variability among various populations. Studies should be carried on all possible ethnic divisions to get an insight into varied drug responsiveness in different populations.

Modifying Effect of Smoking on GSTM1 and NAT2 in Relation to the Risk of Bladder Cancer in Mongolian Population: A Case-Control Study.

Objectives:Tobacco smoking is the predominant risk factor for bladder cancer as it contains cancer-causing chemicals. However, genetic factors may play important role in response towards chemical carcinogens. In this study we aim to investigate genetic polymorphisms of glutathione S-transferase M1 (GSTM1) and N-acetyltransferase 2 (NAT2) as determinants of bladder cancer risk, independently and in combination with tobacco use in the Mongolian population. Materials and Methods:The current study was a hospital-based case-control study including 60 histologically confirmed bladder cancer patients and 60 cancer-free controls. PCR-RFLP assay was used to determine the presence of GSTM1 and NAT2 polymorphisms in bladder cancer patients and controls. GSTM1 and NAT2 were tested using binary logistical regression analysis with adjustment or stratification according to the smoking. Results:There were 46 men and 14 women diagnosed with bladder cancer, with mean age was 58±4. The controls included 37 men and 23 women with a mean age of 57±3. The frequency of GSTM1 null genotype was higher in controls (71.67%) than in bladder cancer patients (58.33%) without statistical significance (OR=0.5534; 95% CI=0.2586-1.1843), (p=0.128). The NAT2 low acetylator phenotype was more common in patients with bladder cancer (15%) than in controls (5%). Furthermore, individuals with NAT2 low acetylator phenotype had a nearly 3.35-fold increased risk to develop bladder cancer (OR=3.35; 95% CI=0.8604-13.0657), (p=0.081) while the risk was even higher when combined with null GSTM1 genotype (OR=4; 95% CI=0.4459-37.5308), (p=0.213) but there was no statistical significance. Prevalence of smoking in bladder cancer patients was higher than controls and increased significantly the risk of bladder cancer (OR=8.31; 95% CI=3.66-18.88). Smokers with GSTM1 null genotype were at 5-fold higher risk of bladder cancer (OR=5.0; 95% CI=1.55-16.16), (p=0.007) while NAT2 low acetylator phenotype increased bladder cancer risk by 20-fold (OR=20.5; 95% CI=2.33-80.86), (p=0.006). Conclusion:The current study shows that tobacco smokers with the NAT2 low acetylator phenotype and GSTM1 null genotype have the highest risk of bladder cancer in the Mongolian population.

Association of N-acetyltransferase-2 Polymorphism with Antituberculosis Induced Hepatotoxicity: A Meta-analysis

Background: N-acetyltransferase (NAT2) polymorphisms were reported to play important roles in antituberculosis-induced hepatotoxicity (ATDIH). However, the allelic types with increased risks for ATDIH were inconsistent as most studies are of a small sample size. Objective: The objective of the study was to conduct a meta-analysis to identify NAT2 alleles associated with increased risks of ATDIH. Methods: Studies reported on NAT2 polymorphism with the risk of ATDIH were searched systematically in PubMed, Scopus, and the World of Sciences. Studies were included if they fulfilled the inclusion criteria and excluded accordingly. Quality assessments were done using Newcastle-Ottawa Score. Statistical analysis was performed using Review Manager version 5.3. Cochrane Q-statistic test and I2 statistic were used to assess and quantify heterogeneity. Results: A total of 12 studies involving 580 cases and 3129 controls were included. NAT2 polymorphism was significantly associated with the risk of ATDIH with an odd ratio (OR) of 2.76 (1.86 – 4.10, 95% CI). Among the slow acetylators genotypes, NAT2*5/*7 carry the highest risk associated with ATDIH. Conclusion: NAT2 polymorphism was significantly associated with ATDIH.

Influence of N-acetyltransferase 2 gene polymorphisms on the in vitro metabolism of the epidermal growth factor receptor inhibitor rociletinib.

Rociletinib showed activity in T790M-positive non-small cell lung cancer patients. It undergoes amide hydrolysis to form M502, followed by N-acetylation to M544 or amide hydrolysis to M460. We identified the enzymes responsible for rociletinib metabolism, and investigated the relationship between M544 formation and N-acetyltransferase 2 (NAT2) polymorphisms. Rociletinib and metabolites were incubated with carboxylesterase (CES)1b, CES1c, CES2, NAT1, NAT2, arylacetamide deacetylase, inhibitors, pooled human liver microsomes (HLM) and cytosols (HLC). Cytosols (n =107) were genotyped for NAT2 polymorphisms (rs1041983 and rs1801280) and incubated with M502. Human hepatocytes from intermediate (NAT2*6/*12A) and slow (NAT2*5B/*5B) acetylators were incubated with 10μM rociletinib and metabolites for 24 hours. Metabolites were measured by high-performance liquid chromatography. M502 was formed from rociletinib and M544 by CES2 and HLM; M544 and N-acetyl-M460 were formed by NAT2 and HLC; M460 was not formed by CES or arylacetamide deacetylase. M502 formation by HLM was inhibited by bis-(4-nitrophenyl)phosphate and eserine (10μM). M544 formation in HLC was inhibited by 100 μM quercetin and was associated with NAT2 genotype (P <.0001). M460 formation in HLM was inhibited by eserine, and M460 was N-acetylated in HLC. Hepatocytes formed M502, M544 and M460. The intermediate acetylator showed higher production (range: 3.4-5.1-fold) of N-acetylated metabolites than the slow acetylator. Results indicate that NAT2 and CES2 are involved in rociletinib metabolism, and polymorphic NAT2 could alter drug exposure in patients. Slow NAT2 acetylators would have higher exposure to M502 and M460 and consequently, be at increased risk of experiencing hyperglycaemia and QTc prolongation.

The Influence of NAT2 Genotypes on Isoniazid Plasma Concentration of Pulmonary Tuberculosis Patients in Southern Thailand.

BackgroundIsoniazid (INH) is metabolized by polymorphic N-acetyltransferase 2 (NAT2) enzyme, which noticeably alters INH plasma concentration. We aimed to determine the distribution of NAT2 genotype in Thai tuberculosis (TB) patients and correlate their genotype with plasma INH concentrations.MethodsBlood samples from 55 newly diagnosed pulmonary tuberculosis participants from three hospitals were collected to classify the subject by NAT2 genotype performed by the Multiplex haplotype-specific polymerase chain reaction method. Patients were grouped into three acetylators (fast, intermediate, and slow). On day 14 of tuberculosis treatment, the second blood sample was taken to estimate the peak plasma concentration at 2 hours after oral administration. INH plasma concentration was analyzed by liquid chromatography‒tandem mass spectrometry/mass spectrometry method.ResultsThe NAT2 genotype distribution of fast, intermediate, and slow acetylator was 10.9%, 36.4%, and 52.7%, from six, 20, and 29 patients, respectively. The median (interquartile range) of INH plasma concentration at 2 hours post drug administration for these three genotypes were 0.75 (0.69–0.86), 2.56 (2.12–3.97), and 4.25 (3.56–5.50) µg/mL from four, 14, and 12 cases, respectively. The INH plasma concentration at 2 hours after administration was significantly associated with body weight and NAT2 acetylator.ConclusionThe INH plasma concentration was found lower in fast than intermediate and slow acetylators. Body weight and NAT2 acetylator influenced INH plasma concentrations at 2 hours after drug administration. Therefore, the NAT2 genotype should be known before starting TB treatment to maximize therapeutic outcomes.

A Systematic Review and Meta-analysis of Isoniazid Pharmacokinetics in Healthy Volunteers and Patients with Tuberculosis

PurposeThis systematic review and meta-analysis assesses the pharmacokinetic (PK) summary estimates of isoniazid (INH) between healthy volunteers and patients with tuberculosis (TB), evaluates whether the current INH dose regimen is appropriate in patients with TB, and evaluates the impact of N-acetyl-transferase-2 (NAT2) status on the PK properties of INH. MethodsA systematic approach was conducted to find studies with relevant INH PK data published in the English language up to February 2018. The PK properties of INH were extracted with their respective INH dosages and were dose normalized to allow a fair comparison between healthy volunteers and patients with TB. Meta-analysis was then performed for the Cmax and AUC estimates for all INH dosages. FindingsNinety studies were included in this systematic review. TB status significantly affected the INH Cmax and AUC estimates. In healthy volunteers, the dose-normalized INH Cmax and AUC were statistically higher than those of patients with TB. No significant differences were found in dose-normalized Cmax and AUC between adults with TB and adults with TB/HIV; however, the AUC in pediatric patients was significantly different between patients with TB and patients with TB/HIV. In addition, no significance was observed comparing the dose-normalized Cmax and AUC of pediatric patients with TB and TB/HIV with their respective adult counterparts. Dose-normalized INH Cmax and AUC in patients with fast and intermediate NAT2 were significantly lower than in patients with slow NAT2. ImplicationsThe current recommended dosages of INH were found to produce less drug exposure in patients with TB when compared with healthy volunteers. NAT2 polymorphism greatly impacts the PK properties of INH; hence, testing for acetylator status is highly recommended, and therapeutic drug monitoring would help reduce INH toxicity.

Variability in the frequency of single nucleotide polymorphisms of N-acetyl transferase 2 (NAT2) gene among the different ethnic groups in Taiwan

Significant variations in the frequency of single nucleotide polymorphisms (SNPs) of human leukocyte antigen among Taiwan's aboriginal tribes and high homogeneity within each tribe have been reported. To identify variations in genetic polymorphisms of drug-metabolizing enzyme in seven of Taiwan's ethnic groups, the SNPs of N-acetyl transferase 2, a conjugation enzyme in phase II metabolism, were investigated. Methods: Three SNPs of NAT2, NAT2*5, NAT2*6, and NAT2*7, were determined by the TaqMan® method and subsequently confirmed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Our results showed statistically significant variations in the frequency of NAT2 genotype categories according to the 3 SNPs of NAT2 within 7 Taiwanese ethnic groups (Chi-square = 32.08, p<0.05). The distribution of the frequency of the slow acetylator genotype ranged from 32.0% in the Hakka population to 75.5% in the Paiwan population. A lack of NAT2*5 SNP alleles was found in the Atayal population, while a NAT2*5 allele frequency of 31.6% was observed in the Paiwan group. The frequencies of allele NAT2*6 and NAT2*7 in the investigated ethnic groups ranged from 11.2-37.0% and 17.0-53%, respectively. Our results also showed the considerable variations in drug-metabolizing enzyme NAT2 genotypes among Taiwan's aboriginal and general population. The variation in the genetic polymorphisms of drug-metabolizing enzyme in Taiwan's groups is worthy of further study to understand different therapeutic and adverse drug responses in ethnic groups.

N-acetyltransferase 2 polymorphism is associated with bladder cancer risk: An updated meta-analysis based on 54 case-control studies.

N-acetyltransferase 2 (NAT2) polymorphism could participate in the metabolism of carcinogens through regulating the activity of a series of critical enzymes. However, the effects of NAT2 polymorphism on bladder cancer (BCa) risk were still inconclusive. In order to illustrate whether NAT2 polymorphism may influence the susceptibility to BCa, we conducted this updated meta-analysis. Databases including PubMed, Medline, Embase, Web of Science, Cochrane Library, and China National Knowledge Infrastructure(CNKI) were systematically retrieved and we applied MetaGenyo to perform final meta-analysis. Odds ratios (ORs) as well as 95% confidence intervals (CIs) were calculated and Bonferroni method was applied to correct the P-value for multiple comparisons. The registration of this study protocol is at PROSPERO and ID is CRD42019133957. Ultimately, 54 case-control studies were identified for final meta-analysis (13343 BCa cases and 18,586 controls). Overall analysis indicated that the slow genotype in NAT2 polymorphism was obviously associated with BCa risk (PBonferroni<0.001). Subgroup analyses demonstrated that significant risk with the slow genotype was observed in Caucasians, Asians, smokers, non-exposed individuals, high grade bladder cancer (HGBC) patients and muscle-invasive bladder cancer (MIBC) patients. In addition, the intermediate NAT2 genotype was revealed to increase the BCa risk of Asians and transitional cell carcinoma (TCC) patients. However, no correlation was identified in Africans with the NAT2 polymorphism. The slow NAT2 genotype was identified to be the risk genotype for BCa. The intermediate genotype could serve as the candidate risk genotype. The gene-smoking interaction with NAT2 polymorphism might accelerate the tumor progression.

Prevalence of polymorphisms in N-acetyltransferase 2 gene among patients of Yakut ethnicity newly diagnosed with pulmonary tuberculosis

Background. Tuberculosis therapy can lead to considerably dissimilar outcomes among individual patients. Some patients benefit from anti-tuberculosis chemotherapy leading to a desired therapeutic effect, while other patients show insufficient or absent response, or develop adverse side effects. Individual response to isoniazid is affected by mutations in the gene encoding N-acetyltransferase 2 (NAT2). Wide variations were observed in distributions of polymorphic NAT2 alleles in human populations depending on race, ethnicity, or geographical origin. No data are available to date on prevalence of NAT2 gene polymorphic variants and acetylation types in Yakut (Sakha) patients with newly diagnosed pulmonary tuberculosis.&#x0D; Aims: the frequencies of NAT2 polymorphic SNPs as well isoniazid acetylation phenotypes were evaluated in the patients cohort of Yakut ethnicity with newly diagnosed pulmonary tuberculosis (PTB). The comparison with, other ethnic groups of Asian origin was done.&#x0D; Methods. Cross-sectional study was conducted among Yakut patient cohorts with newly identified pulmonary tuberculosis. Using real-time PCR the following SNPs were explored: NAT2*5 (rs1801280, Т341С), NAT2*6 (rs1799930, G590A), NAT2*7 (rs1799931, G857A), NAT2*11 (rs1799929, C481T), NAT2*12 (rs1208, A803G), NAT2*13 (rs1041983, C282T). Genetically determined metabolic rates were calculated using NATpred online tool.&#x0D; Results. NAT2 SNPs were assessed, namely *5, *6, *7, *11, *12, and *13. The most frequent in Yakut patients were NAT2*6 and NAT2*13 SNPs (40.9% and 64.4%, respectively). Significant differences were detected in frequencies of NAT2 *5, *11, *12 polymorphisms; all studied NAT2 gene polymorphisms showed meaningful differences in genotype and minor allele prevalence rates after comparison between Yakut population and other Mongoloid ethnic groups (populations of China, Japan, Vietnam). High prevalence of intermediate acetylation type among ethnic Yakuts (58.3%) was established.&#x0D; Conclusions. Certain distinct differences in allelic variants of NAT2 gene and acetylation type prevalence in patients of Yakut ethnic origin newly diagnosed with pulmonary tuberculosis let conclude that the existing genotyping and phenotyping data from studies among other Mongoloid populations cannot be implicitly extrapolated on Yakut people. Pharmacogenetic data on individual response to drugs in Yakut patients should be made use of in clinical practice, to develop personalized isoniazid administration algorithms, with a final goal to make treatment more effective and safe.

Study on Genotyping Polymorphism and Sequencing of N-Acetyltransferase 2 (NAT2) among Al-Ahsa Population.

One of the well-studied phase II drug metabolizing enzymes is N-acetyltransferase 2 (NAT2) which has an essential role in the detoxification and metabolism of several environmental toxicants and many therapeutic drugs like isoniazid (antituberculosis, TB) and antimicrobial sulfonamides. According to the variability in the acetylation rate among different ethnic groups, individuals could be classified into slow, intermediate, and fast acetylators; these variabilities in the acetylation rate are a result of single nucleotide polymorphisms (SNPs) in the coding sequence of NAT2. The variety of NAT2 acetylation status is associated with some diseases such as bladder cancer, colorectal cancer, rheumatoid arthritis, and diabetes mellitus. The main objectives of this research are to describe the genetic profile of NAT2 gene among the people of the Al-Ahsa region, to detect the significant SNPs of this gene, to determine the frequency of major NAT2 alleles and genotypes, and then categorize them into fast, intermediate, and slow acetylators. Blood samples were randomly collected from 96 unrelated people from Al-Ahsa population, followed by DNA extraction then amplifying the NAT2 gene by polymerase chain reaction (PCR); finally, functional NAT2 gene (exon 2) was sequenced using the Sanger sequencing method. The well-known seven genetic variants of NAT2 gene are 191G>A, 282C>T, 341T>C, 481C>T, 590G>A, 803A>G, and 857G>A were detected with allele frequencies 1%, 35.4%, 42.7%, 41.1%, 29.2%, 51%, and 5.7%, respectively. The most common NAT2 genetic variant among Al-Ahsa population was 803A>G with a high frequency 0.510 (95% confidence interval 0.44-0.581) followed by 341T>C 0.427 (95% confidence interval 0.357-0.497). The most frequent two haplotypes of NAT2 were NAT2∗6C (25.00%) and NAT2∗5A (22.92%) which were classified as a slow acetylators. According to trimodal distribution of acetylation activity, the predicted phenotype of Al-Ahsa population was found to be 5.21% rapid acetylators, 34.38% intermediate acetylators, and 60.42% were slow acetylators. In addition, this study found four novel haplotypes NAT2∗5TB, NAT2∗5AB, NAT2∗5ZA, and NAT2∗6W which were slow acetylators. This study revealed a high frequency of the NAT2 gene with slow acetylators (60.42%) in Al-Ahsa population, which might alter the drug's efficacy and vulnerability to some diseases.