Determination of NAT2 Genotypes in a Cohort of Patients with Suspected TB in the State of Rio de Janeiro.

The human N-acetyltransferase 2 enzyme, encoded by the NAT2 gene, plays an important role in the metabolism of isoniazid, the main drug used to treat tuberculosis. The interindividual variation in the response of patients to drug treatment for tuberculosis may be responsible for the occurrence of unfavorable outcomes. The presence of polymorphisms in genes associated with the metabolism and transport of drugs, receptors, and therapeutic targets has been identified as a major determinant of this variability. The objective of this study was to identify the genetic profile of NAT2 in the study population. Using the obtained genomic DNA followed by PCR amplification and sequencing, the frequency of nine SNPs as well as alleles associated with slow (47.9%), intermediate (38.7%), and fast acetylation phenotypes (11.3%), in addition to those whose phenotype has not yet been characterized (2.1%), was estimated. The NAT2*5B allele was identified more frequently (31.3%). The description of SNPs in pharmacogenes and the establishment of their relationship with the pharmacokinetics of an individual offer an individualized approach that allows us to reduce the unfavorable outcomes of a therapy, ensure better adherence to treatment, prevent the emergence of MDR strains, reduce the cost of treatment, and improve the quality of patients' lives.

Human N-acetyltransferase 2 (NAT2) gene variability in Brazilian populations from different geographical areas.

Introduction: Several polymorphisms altering the NAT2 activity have already been identified. The geographical distribution of NAT2 variants has been extensively studied and has been demonstrated to vary significantly among different ethnic population. Here, we describe the genetic variability of human N-acetyltransferase 2 (NAT2) gene and the predominant genotype-deduced acetylation profiles of Brazilians. Methods: A total of 964 individuals, from five geographical different regions, were genotyped for NAT2 by sequencing the entire coding exon. Results: Twenty-three previously described NAT2 single nucleotide polymorphisms (SNPs) were identified, including the seven most common ones globally (c.191G>A, c.282C>T, c.341T>C, c.481C>T, c.590G>A, c.803A>G and c.857G>A). The main allelic groups were NAT2*5 (36%) and NAT2*6 (18.2%), followed to the reference allele NAT2*4 (20.4%). Combined into genotypes, the most prevalent allelic groups were NAT2*5/*5 (14.6%), NAT2*5/*6 (11.9%) and NAT2*6/*6 (6.2%). The genotype deduced NAT2 slow acetylation phenotype was predominant but showed significant variability between geographical regions. The prevalence of slow acetylation phenotype was higher in the Northeast, North and Midwest (51.3%, 45.5% and 41.5%, respectively) of the country. In the Southeast, the intermediate acetylation phenotype was the most prevalent (40.3%) and, in the South, the prevalence of rapid acetylation phenotype was significantly higher (36.7%), when compared to other Brazilian states (p < 0.0001). Comparison of the predicted acetylation profile among regions showed homogeneity among the North and Northeast but was significantly different when compared to the Southeast (p = 0.0396). The Southern region was significantly different from all other regions (p < 0.0001). Discussion: This study contributes not only to current knowledge of the NAT2 population genetic diversity in different geographical regions of Brazil, but also to the reconstruction of a more accurate phenotypic picture of NAT2 acetylator profiles in those regions.

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

BACKGROUND: In 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. METHODS: In 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. RESULTS: We 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. CONCLUSION: We 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.

Allelic and genotypic frequencies of NAT2, CYP2E1, and AADAC genes in a cohort of Peruvian tuberculosis patients.

BACKGROUND: We determined the frequency of genetic polymorphisms in three anti-TB drug metabolic proteins previously reported: N-acetyltransferase 2 (NAT2), cytochrome P450 2E1 (CYP2E1), and arylacetamide deacetylase (AADAC) within a Peruvian population in a cohort of TB patients. METHODS: We genotyped SNPs rs1041983, rs1801280, rs1799929, rs1799930, rs1208, and rs1799931 for NAT2; rs3813867 and rs2031920 for CYP2E1; and rs1803155 for AADAC in 395 participants completed their antituberculosis treatment. RESULTS: Seventy-four percent of the participants are carriers of slow metabolizer genotypes: NAT2*5, NAT2*6, and NAT2*7, which increase the sensitivity of INH at low doses and increase the risk of drug-induced liver injuries. Sixty-four percent are homozygous for the wild-type CYP2E1*1A allele, which could increase the risk of hepatotoxicity. However, 16% had a NAT2 fast metabolizer phenotype which could increase the risk of acquiring resistance to INH, thereby increasing the risk of multidrug-resistant (MDR) or treatment failure. The frequency of rs1803155 (AADAC*2 allele) was higher (99.9%) in Peruvians than in European American, African American, Japanese, and Korean populations. CONCLUSIONS: This high prevalence of slow metabolizers for isoniazid in the Peruvian population should be further studied and considered to help individualize drug regimens, especially in countries with a great genetic diversity like Peru. These data will help the Peruvian National Tuberculosis Control Program develop new strategies for therapies.

NAT2 polymorphisms associated with the development of hepatotoxicity after first-line tuberculosis treatment in Mexican patients: From genotype to molecular structure characterization.

BACKGROUND AND AIMS: To assess the relevance of the slow acetylator phenotype based on NAT2 genotypes, among patients with pulmonary tuberculosis (PTB) that developed hepatotoxicity after first-line tuberculosis treatment in a Northeastern Mexican population. METHODS: Ninety one PTB patients were included, 7 of them developed hepatotoxicity. NAT2 SNPs (rs1801279, rs1041983, rs1801280, rs1799929, rs1799930, rs1208, and rs1799931) were genotyped by TaqMan allelic discrimination assay. Statistical analyses were performed using Epi Info statistical software 7.0 and SHEsisPlus for haplotype reconstruction. The NAT2 slow non-synonymous SNP were studied by molecular dynamic analysis (MDA). RESULTS: The frequency of the haplotype associated with slow acetylation status for PTB was 58%, and for with hepatotoxicity (PTB-H) represented 42.6%. Three haplotypes, NAT2*5Q, NAT2*5U, NAT2*5Va were exclusively present in seven PTB-H patients, (P = 0.01, P = 0.0006, P = 0.01, respectively). These haplotypes include the combination of two SNPs (I114T + R197Q or I114T + G286E). The effect of the SNPs on protein structure is to disrupt the CoA binding site affecting acetylation activity. CONCLUSION: Our study provides insight into slow acetylation NAT2 haplotypes associated with hepatotoxicity after first-line tuberculosis treatment, for first time, in a Mexican population. The molecular mechanism acts at the CoA binding site.

Genotype-Environment Interaction Analysis of NQO1, CYP2E1, and NAT2 Polymorphisms and the Risk of Childhood Acute Lymphoblastic Leukemia: A Report From the Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia.

Background: Acute lymphoblastic leukemia (ALL) is the main type of cancer in children. In Mexico and other Hispanic populations, the incidence of this neoplasm is one of the highest reported worldwide. Functional polymorphisms of various enzymes involved in the metabolism of xenobiotics have been associated with an increased risk of developing ALL, and the risk is different by ethnicity. The aims of the present study were to identify whether NQO1, CYP2E1, and NAT2 polymorphisms or some genotype-environmental interactions were associated with ALL risk in Mexican children. Methods: We conducted a case-control study including 478 pediatric patients diagnosed with ALL and 284 controls (children without leukemia). Ancestry composition of a subset of cases and controls was assessed using 32 ancestry informative markers. Genetic-environmental interactions for the exposure to hydrocarbons were assessed by logistic regression analysis. Results: The polymorphisms rs1801280 (OR 1.54, 95% CI 1.21-1.93), rs1799929 (OR 1.96, 95% CI 1.55-2.49), and rs1208 (OR 1.44, 95% CI 1.14-1.81) were found to increase the risk of ALL; being the risks higher under a recessive model (OR 2.20, 95% CI 1.30-1.71, OR 3.87, 95% CI 2.20-6.80, and OR 2.26, 95% CI 1.32-3.87, respectively). Gene-environment interaction analysis showed that NAT2 rs1799929 TT genotype confers high risk to ALL under exposure to fertilizers, insecticides, hydrocarbon derivatives, and parental tobacco smoking. No associations among NQO1, CYP2E1, and ALL were observed. Conclusion: Our study provides evidence for the association between NAT2 polymorphisms/gene-environment interactions, and the risk of childhood ALL in Mexican children.

Population pharmacokinetics of isoniazid and dose recommendations in Mexican patients with tuberculosis.

Background The standardized doses of isoniazid in therapy against tuberculosis are determined based on total body weight, without considering genetic polymorphisms of the metabolic enzyme N-acetyltransferase-2 that contribute to the wide pharmacokinetic variability of isoniazid. Objective The aim of this work was to build a population pharmacokinetic model of isoniazid in Mexican patients with tuberculosis to characterize typical estimates of pharmacokinetics, as well as inter-individual and residual variability of isoniazid considering the genetic factors associated with the N-acetyltransferase-2 enzyme. Setting A prospective study was conducted at the Department of Internal Medicine in Hospital Central, San Luis Potosí, México. Methods Plasma concentrations of isoniazid were measured by high performance liquid chromatography. The acetylator phenotype was predicted through single nucleotide polymorphisms in the N-acetyltransferase-2 gene. Genetic, anthropometric and clinical covariates were used to develop a pharmacokinetic model. Main outcome measure Isoniazid plasma concentration. Results A total of 69 patients with tuberculosis were included. Blood samples were drawn from 20 min to 12 h post dose to determinate the isoniazid plasma concentration. Typical pharmacokinetics parameters were characterized through two-compartment open model with first-order absorption and linear elimination. Clearance was different for each predicted N-acetyltransferase-2 phenotype being 11.4, 19.2 and 27.4 L/h for slow, intermediate and rapid acetylators, respectively. Central volume of distribution was determined as 1.5 * body mass index (L). Through the application of the model, external validation was performed and initial dose regimen of isoniazid is proposed based on stochastic simulations. Conclusion A validated population pharmacokinetic model of isoniazid was developed in Mexican patients with tuberculosis. Through the application of the final model, initial dose recommendations were provided considering body mass index and N-acetyltransferase-2 phenotype.

NAT2 gene polymorphisms in three indigenous groups in the Colombian Caribbean Coast region / Polimorfismo del Gen NAT2 en tres grupos indígenas de la región Caribe Colombiana

Objective: To study the NAT2 gene polymorphisms 481T, 590A and 857A in the Chimila, Wiwa and Wayuu indigenous groups of the Colombian Caribbean to determine the frequencies of the alleles NAT2*4, NAT2*5, NAT2*6, and NAT2*7 and to determine the types of acetylators present in these populations. Methods: A total of 202 subjects were studied: 47 Chimila, 55 Wiwa, and 100 Wayuu. The polymorphisms were identified using a real-time PCR method for allelic discrimination designed using Taqman of Applied Biosystems. Results: The following alleles were found at the highest frequency in the following groups: the NAT2*4 allele (wild type) in the Wayuu group (55.3%), the NAT2*5 allele in the Wiwa group (34.5%), and the NAT2*7 allele in the Chimila group (24.2%). A higher frequency of the rapid acetylator status was found in the Wayuu group (31.3%) and Chimila group (29.5%) compared with the Wiwa group (12.7%). The intermediate acetylator status distribution was very similar in all three groups, and the frequency of the slow acetylator status was higher in the Wiwa group (32.7%) compared with the Chimila and Wayuu groups (20.5% and 21.2%, respectively). Conclusion: The results demonstrated the allelic distribution and pharmacogenetic differences of the three groups studied and revealed the most frequent acetylator status and phenotype. Because of the high prevalence of slow acetylators, a greater incidence of tuberculosis (TB) drug-induced hepatotoxicity is predicted in these populations, with a higher frequency in the Wiwa group.

Objetivo: Estudiar los polimorfismos tipo SNP (del inglés- single nucleotide polymorphism) 481T, 590A y 857A del gen NAT2, en los grupos indígenas Chimila, Wiwa y Wayúu del Caribe Colombiano para determinar las frecuencias de los alelos NAT2*4, NAT2*5, NAT2*6 y NAT2*7 y caracterizar el tipo de acetiladores presentes en estas poblaciones. Métodos: Se estudiaron 202 individuos en total, 47 Chimila, 55 Wiwa y 100 Wayúu. Los polimorfismos se determinaron mediante la técnica de PCR en tiempo real por el método de discriminación alélica Taqman de Applied Biosystems. Resultados: El alelo NAT2*4 (wild type) mostró una mayor frecuencia en el grupo Wayúu (55.3%), el alelo NAT2*5 en el grupo Wiwa (34.5%) y el alelo NAT2*7 en el grupo Chimila (24.2%). Se encontró una mayor frecuencia del estado acetilador rápido en el grupo Wayúu (31.3%) y en el grupo Chimila (29.5%) al compararse con el grupo Wiwa (12.7%). La distribución del estado acetilador intermedio es muy similar en los tres grupos, y para el estado acetilador lento observamos que en el grupo Wiwa la frecuencia es mayor (32.7%) con respecto a Chimila y Wayúu con 20.5% y 21.2% respectivamente. Conclusiones: Los resultados permitieron conocer la distribución alélica y el componente farmacogenético de los tres grupos estudiados; igualmente, deducir el estado acetilador y/o fenotipo más frecuente. Debido a la alta prevalencia de acetiladores lentos, se podría predecir un aumento de la incidencia de hepatotóxicidad inducida por medicamentos antituberculosos como la Isoniacida indicados en estas poblaciones y en mayor frecuencia en el grupo Wiwa.

NAT2 gene polymorphisms in three indigenous groups in the Colombian Caribbean Coast region.

OBJECTIVE: To study the NAT2 gene polymorphisms 481T, 590A and 857A in the Chimila, Wiwa and Wayuu indigenous groups of the Colombian Caribbean to determine the frequencies of the alleles NAT2*4, NAT2*5, NAT2*6, and NAT2*7 and to determine the types of acetylators present in these populations. METHODS: A total of 202 subjects were studied: 47 Chimila, 55 Wiwa, and 100 Wayuu. The polymorphisms were identified using a real-time PCR method for allelic discrimination designed using Taqman of Applied Biosystems. RESULTS: The following alleles were found at the highest frequency in the following groups: the NAT2*4 allele (wild type) in the Wayuu group (55.3%), the NAT2*5 allele in the Wiwa group (34.5%), and the NAT2*7 allele in the Chimila group (24.2%). A higher frequency of the rapid acetylator status was found in the Wayuu group (31.3%) and Chimila group (29.5%) compared with the Wiwa group (12.7%). The intermediate acetylator status distribution was very similar in all three groups, and the frequency of the slow acetylator status was higher in the Wiwa group (32.7%) compared with the Chimila and Wayuu groups (20.5% and 21.2%, respectively). CONCLUSION: The results demonstrated the allelic distribution and pharmacogenetic differences of the three groups studied and revealed the most frequent acetylator status and phenotype. Because of the high prevalence of slow acetylators, a greater incidence of tuberculosis (TB) drug-induced hepatotoxicity is predicted in these populations, with a higher frequency in the Wiwa group.

OBJETIVO: Estudiar los polimorfismos tipo SNP (del inglés-single nucleotide polymorphism) 481T, 590A y 857A del gen NAT2, en los grupos indígenas Chimila, Wiwa y Wayúu del Caribe Colombiano para determinar las frecuencias de los alelos NAT2*4, NAT2*5, NAT2*6 y NAT2*7 y caracterizar el tipo de acetiladores presentes en estas poblaciones. MÉTODOS: Se estudiaron 202 individuos en total, 47 Chimila, 55 Wiwa y 100 Wayúu. Los polimorfismos se determinaron mediante la técnica de PCR en tiempo real por el método de discriminación alélica Taqman de Applied Biosystems. RESULTADOS: El alelo NAT2*4 (wild type) mostró una mayor frecuencia en el grupo Wayúu (55.3%), el alelo NAT2*5 en el grupo Wiwa (34.5%) y el alelo NAT2*7 en el grupo Chimila (24.2%). Se encontró una mayor frecuencia del estado acetilador rápido en el grupo Wayúu (31.3%) y en el grupo Chimila (29.5%) al compararse con el grupo Wiwa (12.7%). La distribución del estado acetilador intermedio es muy similar en los tres grupos, y para el estado acetilador lento observamos que en el grupo Wiwa la frecuencia es mayor (32.7%) con respecto a Chimila y Wayúu con 20.5% y 21.2% respectivamente. CONCLUSIONES: Los resultados permitieron conocer la distribución alélica y el componente farmacogenético de los tres grupos estudiados; igualmente, deducir el estado acetilador y/o fenotipo más frecuente. Debido a la alta prevalencia de acetiladores lentos, se podría predecir un aumento de la incidencia de hepatotóxicidad inducida por medicamentos antituberculosos como la Isoniacida indicados en estas poblaciones y en mayor frecuencia en el grupo Wiwa.

Association of slow acetylation profile of NAT2 with breast and gastric cancer risk in Brazil.

BACKGROUND: The N-acetyltransferase 2 (NAT2) gene is a marker for the study of interindividual susceptibility to developing neoplasias. The purpose of this study was to verify a possible association between single nucleotide polymomorphisms (SNPs) of NAT2 and the susceptibility to gastric cancer (GC) and breast cancer (BC) in patients from the North region of Brazil. MATERIALS AND METHODS: Five SNPs of the NAT2 gene were investigated by direct sequencing. Ancestry was estimated by analysis of a panel with 48 ancestry-informative markers (AIM). RESULTS: Individuals with slow acetylation profile had an increased risk of developing neoplasias up to three times when compared to controls. CONCLUSION: In this study, slow acetylation profile was found to strongly influence susceptibility to GC and BC.

Polymorphisms of arylamine N-acetyltransferase2 and risk of lung and colorectal cancer.

The arylamine N-acetyltransferase 2 (NAT2) enzymes detoxify a wide range of naturally occurring xenobiotics including carcinogens and drugs. Point mutations in the NAT2 gene result in the variant alleles M1 (NAT2 *5A), M2 (NAT2*6A), M3 (NAT2*7) and M4 (NAT2 *14A) from the wild-type WT (NAT2 *4) allele. The current study was aimed at screening genetic polymorphisms of NAT2 gene in 49 lung cancer patients, 54 colorectal cancer patients and 99 cancer-free controls, using PCR-RFLP. There were significant differences in allele frequencies between lung cancer patients and controls in the WT, M2 and M3 alleles (p < 0.05). However, only M2 and M3 allele frequencies were different between colorectal cancer patients and controls (p < 0.05). There was a marginal significant difference in the distribution of rapid and slow acetylator genotypes between lung cancer patients and controls (p = 0.06 and p = 0.05, respectively), but not between colorectal cancer patients and controls (p = 1.0 and p = 0.95, respectively). Risk of lung cancer development was found to be lower in slow acetylators [odds ratio (OR): 0.51, 95% confidence interval (95% CI): 0.25, 1.02, p-value = 0.07]. No effect was observed in case of colorectal cancer. Our results showed that NAT2 genotypes and phenotypes might be involved in lung cancer but not colorectal cancer susceptibility in Jordan.

Genetic polymorphisms of NAT2, CYP2E1 and GST enzymes and the occurrence of antituberculosis drug-induced hepatitis in Brazilian TB patients

Isoniazid (INH), one of the most important drugs used in antituberculosis (anti-TB) treatment, is also the major drug involved in hepatotoxicity. Differences in INH-induced toxicity have been attributed to genetic variability at several loci, such as NAT2, CYP2E1, GSTM1 and GSTT1, that code for drug-metabolising enzymes. Our goal was to examine the polymorphisms in these enzymes as susceptibility factors to anti-TB drug-induced hepatitis in Brazilian individuals. In a case-control design, 167 unrelated active tuberculosis patients from the University Hospital of the Federal University of Rio de Janeiro, Brazil, were enrolled in this study. Patients with a history of anti-TB drug-induced acute hepatitis (cases with an increase to 3 times the upper limit of normal serum transaminases and symptoms of hepatitis) and patients with no evidence of anti-TB hepatic side effects (controls) were genotyped for NAT2, CYP2E1, GSTM1 and GSTT1 polymorphisms. Slow acetylators had a higher incidence of hepatitis than intermediate/rapid acetylators [22 percent (18/82) vs. 9.8 percent (6/61), odds ratio (OR), 2.86, 95 percent confidence interval (CI), 1.06-7.68, p = 0.04). Logistic regression showed that slow acetylation status was the only independent risk factor (OR 3.59, 95 percent CI, 2.53-4.64, p = 0.02) for the occurrence of anti-TB drug-induced hepatitis during anti-TB treatment with INH-containing schemes in Brazilian individuals.