N-acetyltransferase 2 (NAT2) gene polymorphism as a predisposing factor for phenytoin intoxication in tuberculous meningitis or tuberculoma patients having seizures - A pilot study.

Background & objectives: Simultaneous administration of phenytoin and isoniazid (INH) in tuberculous meningitis (TBM) or tuberculoma patients with seizures results in higher plasma phenytoin level and thus phenytoin intoxication. N-acetyltransferase 2 (NAT2) enzyme catalyses two acetylation reactions in INH metabolism and NAT2 gene polymorphism leads to slow and rapid acetylators. The present study was aimed to evaluate the effect of allelic variants of N-acetyltransferase 2 (NAT2) gene as a predisposing factor for phenytoin toxicity in patients with TBM or tuberculoma having seizures, and taking INH and phenytoin simultaneously. Methods: Sixty patients with TBM or tuberculoma with seizures and taking INH and phenytoin simultaneously for a minimum period of seven days were included in study. Plasma phenytoin was measured by high performance liquid chromatography. NAT2 gene polymorphism was studied using restriction fragment length polymorphism and allele specific PCR. Results: The patients were grouped into those having phenytoin intoxication and those with normal phenytoin level, and also classified as rapid or slow acetylators by NAT2 genotyping. Genotypic analysis showed that of the seven SNPs (single nucleotide polymorphisms) of NAT2 gene studied, six mutations were found to be associated with phenytoin intoxication. For rs1041983 (C282T), rs1799929 (C481T), rs1799931 (G857A), rs1799930 (G590A), rs1208 (A803G) and rs1801280 (T341C) allelic variants, the proportion of homozygous mutant was higher in phenytoin intoxicated group than in phenytoin non-intoxicated group. Interpretation & conclusions: Homozygous mutant allele of NAT2 gene at 481site may act as a predisposing factor for phenytoin intoxication among TBM or tuberculoma patients having seizures.

Allelic frequencies of single nucleotide polymorphisms (SNPs) in the N-acetyltransferase 2 (NAT2) gene of Filipinos

OBJECTIVES:The present study aims to determine the frequency of occurrence of NAT2*4, NAT2*5A, NAT2*6B, NAT2*7A and NAT2*14A alleles by PCR-RFLP among Filipino volunteers. These alleles correspond to substitutions in the following sites: C341T, G590A, G857A and G191A, respectively, of the NAT2 gene. The presence of specific SNP combination was also used to deduce acetylation status and estimate genotype frequency and describe them in comparison with other populations based on literature. METHODS: Genomic DNA from peripheral blood lymphocytes from 129 healthy Filipino volunteers was used to amplify the NAT2 gene segment. The RFLP analysis was done by restricting the expected PCR product with Kpn1, Taq1, BamH1 and Msp1/Al1, respectively, to detect the 4 alleles: NAT2*4, NAT2*5A, NAT2*6B, NAT2*7A and NAT2*14A. RESULTS:The calculated allelic frequencies in Hardy-Weinberg equilibrium of NAT2*5A (C481T), NAT2*6B (G590A), NAT2*7A (G857A) and NAT2*14A (G191A) were 0.058, 0.097, 0.182 and 0.046, respectively. NAT2*4 had an allele frequency of 0.617. Nine genotypes were determined: NAT2*4/*4, NAT2*4/*5A, NAT2*4/*6B, NAT2*4/*7A, NAT2*4/*14A, NAT2*5A/*7A, NAT2*6B/*7A, NAT2*6B/*14A and NAT2*7A/*14A. From these genotypes, acetylator phenotypes were deduced. A trimodal pattern of distribution was established: rapid, intermediate and slow acetylators with the following percentages, 47.3%, 41.1 % and 11.6%. Among the slow acetylator SNPs determined, NAT2*7A was found as the most frequent allele and NAT2*14A was found as the least frequent allele. CONCLUSION:The study showed the mutation profile and observed genotypic similarities and differences of Filipinos with other Asian populations and Americans and other Caucasians based on literature. The results also suggest a trimodal pattern of distribution of acetylators and lesser number of slow acetylators among Filipino populations, a characteristic similar to other Asian populations but significantly different from Americans and other Caucasians. The occurrence of NAT2*7A and NAT2*14A can be further sequenced to verify the observed genotype.

N-acetyl Transferase 2 Gene Polymorphisms in Patients with Endometriosis / 대한산부인과학회잡지

OBJECTIVE: To explore the association of the N-acetyl transferase 2 (NAT 2) gene polymorphisms with endometriosis. METHODS: One hundred seventy-two women with surgically or histologically diagnosed endometriosis of stages I-IV, and 205 patients with no evidence of endometriosis by laparoscopy or laparotomy served as control. Genotype distribution of NAT 2 polymorphisms and frequencies of slow and fast acetylators in affected women and controls were evaluated. RESULTS: There was no statistically significant difference in the genotype distribution of NAT 2 polymorphisms and frequencies of slow and fast acetylators between the patients with endometriosis and the controls. CONCLUSION: These results suggest that N-acetyl transferase 2 gene polymorphisms is not associated with the risk for endometriosis in the Korean population.

Relationship between polymorphism of N-acetyltransferase 2 gene and susceptibility to bladder cancer / 中华泌尿外科杂志

Objective To investigate the relationship between genetic polymorphism of N-acetyltransferase 2(NAT2) and susceptibility to bladder cancer.Methods Based on case-control study,NAT2 mutation alleles(NAT2*5,*6 and*7) were determined by ASPCR and PCR-RFLP in 78 patients with bladder cancer and 80 nontumorous patients.In addtion,the relationships between the genotypes and tobacco smoking,occupational exposure,high dose intake of meat or pathological characteristic of bladder cancer patients were analyzed.Results In the blood samples from 158 cases,the 4 alleles NAT2*4,NAT2*5,NAT2*6 and NAT2*7 were detected.The frequency of NAT2 slow genotypes was 29.5%(23/78) in patients with bladder cancer,which was significantly higher compared with 16.3%(13/80) in control patients(P