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.
Highlights
Human N-acetyltransferase 2 (NAT2) gene has a key role in the metabolism of hydrazines, arylamines, several environmental toxicants, and therapeutic drugs like isoniazid and the antimicrobial sulfonamides by the N-acetylation of aromatic amines as well as the O-acetylation of carcinogenic heterocyclic amines [1]
The interest of studying the variability in N-acetylation status of NAT2 has been increased among ethnic groups due to the importance of NAT2 polymorphism as biomarkers to evaluate the efficacy of therapy and toxicity during treatment or minimization of adverse drug reactions (ADR) [3]
There is a relationship between NAT2 acetylation status with some diseases like bladder cancer, colorectal cancer, BioMed Research International rheumatoid arthritis, and diabetes [3]
Summary
Human NAT2 gene has a key role in the metabolism of hydrazines, arylamines, several environmental toxicants, and therapeutic drugs like isoniazid and the antimicrobial sulfonamides by the N-acetylation of aromatic amines as well as the O-acetylation of carcinogenic heterocyclic amines [1] This gene is present on the chromosome number 8, at Cytoband p22, and has a coding region of exon 2 with 870 bp which encodes 290 amino acids, and it is mainly expressed in the liver and small intestine [2]. According to the variability in the acetylation rate among different ethnic groups, individuals are classified based on acetylation phenotypes as slow, intermediate, and rapid acetylators This variability in the acetylation rate is a result of SNPs in the coding sequence of NAT2 [4]. The wild-type NAT2∗4 allele does not have any nucleotide substitutions and is associated with fast acetylator phenotype [7]
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