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

Abstract

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.

Allelic and Genotypic Frequencies of NAT2, CYP2E1 and AADAC genes in a cohort of Peruvian Tuberculosis Patients

“…The relationship of NAT2 polymorphisms with INH-induced hepatotoxicity in TB patients among different populations were studied [14–21], but the previously published studies have demonstrated inconsistent results. Therefore, analysis of the slow genotypes should become part of the dosage regimen of INH in TB patients undergoing anti-TB treatment to prevent drug-induced liver injuries [18–21].…”

Genetic polymorphism of the drug-metabolizing enzyme Cytochrome P4502E1 (CYP2E1) in a healthy Saudi population

“…A previous study by Yu et al (2020) reported that CYP2E1*1B polymorphism was associated with an increased risk of isoniazid-induced hepatotoxicity. Furthermore, a recent study by Zahra et al (2020) revealed a high frequency of the NAT2 gene with slow acetylators in the Saudi population. Importantly, the combination of the CYP2E1*1B genotype with a slow acetylator NAT2 genotype increased the risk of isoniazid-induced hepatotoxicity ( An et al, 2012 ).…”

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

“…The relationship of NAT2 polymorphisms with INH-induced hepatotoxicity in TB patients among different populations were studied (Azuma et al, 2013;Borlak & Reamon-Buettner, 2006;Cascorbi et al, 1995;Ganachari et al, 2010;Huerta-García et al, 2020;Sekine et al, 2001;Tiis et al, 2020;Zahra et al, 2020), but the previously published studies have demonstrated inconsistent results. Therefore, analysis of the slow genotypes should become part of the dosage regimen of INH in TB patients undergoing anti-TB treatment to prevent drug-induced liver injuries (Azuma et al, 2013;Ganachari et al, 2010;Huerta-García et al, 2020;Zahra et al, 2020). After NAT2 acetylates INH converting it to acetyl-INH, it can enter the CYP2E1 pathway, which couples with the glutathione-S-transferase (GST) metabolic pathway to facilitate the elimination of toxic metabolites (Guio, Levano, Sánchez, et al, ;Singla et al, 2014;Teixeira et al, 2011).…”

“…Additionally, our study revealed that the genotype frequency (predicted phenotype) of slow metabolizers is ~47%. The relationship of NAT2 polymorphisms with INH‐induced hepatotoxicity in TB patients among different populations were studied (Azuma et al, 2013 ; Borlak & Reamon‐Buettner, 2006 ; Cascorbi et al, 1995 ; Ganachari et al, 2010 ; Huerta‐García et al, 2020 ; Sekine et al, 2001 ; Tiis et al, 2020 ; Zahra et al, 2020 ), but the previously published studies have demonstrated inconsistent results. Therefore, analysis of the slow genotypes should become part of the dosage regimen of INH in TB patients undergoing anti‐TB treatment to prevent drug‐induced liver injuries (Azuma et al, 2013 ; Ganachari et al, 2010 ; Huerta‐García et al, 2020 ; Zahra et al, 2020 ).…”