Elsevier

Biochemical Pharmacology

Volume 58, Issue 11, 1 December 1999, Pages 1759-1764
Biochemical Pharmacology

Original Articles
Correlation between genotype and phenotype of the human arylamine N-acetyltransferase type 1 (NAT1)

https://doi.org/10.1016/S0006-2952(99)00269-5Get rights and content

Abstract

Arylamine N-acetyltransferase 1 (NAT1) conjugates several aromatic amines and their N-hydroxylated metabolites by N- or O-acetylation. NAT1 genotype and phenotype is known to be variable in human populations. In this study, we set out to measure the functional relevance of the frequent NAT1 gene variants for the activity in human red blood cells. Healthy German volunteers (N = 314) were genotyped for NAT1 alleles ∗3, ∗4, ∗10, ∗11, ∗14, and ∗15 using polymerase chain reactions and restriction fragment length pattern analysis, and NAT1 enzyme kinetic parameters were measured in a subset of 105 individuals using p-aminobenzoic acid as specific substrate. There was no functional difference between NAT1 alleles ∗4 and ∗10. In particular, there was no trend of increasing activity from NAT1∗4/∗4 to ∗4/∗10 and ∗10/∗10. Carriers of the NAT1∗11 and ∗14 alleles had a statistically significant lower enzyme activity compared with carriers of the ∗3, ∗4, or ∗10 alleles. Compared with the wild-type genotype NAT1∗4/∗4, activity of the NAT1∗11/∗11, NAT1∗11/∗10, and NAT1∗11/∗4 genotypes was reduced by 20.7%, 35.7%, and 31.5%, respectively. Activity of the NAT1∗10/∗14 and NAT1∗4/∗14 genotypes was reduced by 49.8% and 55.6%, respectively. The difference in NAT1 activity between the ∗4/∗11 and ∗4/∗14 genotypes was also significant (P < 0.01). The carrier of the NAT1∗15/∗15 genotype had no detectable enzyme activity. In conclusion, functional consequences of NAT1 mutations were tested in a large population. Activity in carriers of NAT1 alleles ∗3, ∗4, and ∗10 did not differ, alleles NAT1∗11 and ∗14 appeared to be low activity alleles, and allele NAT1∗15 had no activity.

Section snippets

Volunteers

Venous blood samples were taken from 314 non-smoking healthy German male volunteers (19–48 years of age) after written informed consent. For the phenotyping assay, whole blood samples were drawn into 10-mL vials with ethylene diamine tetraacetic acid as anticoagulant and stored at −80°. Representative subsets of the frequent genotypes ∗4/∗4 and ∗4/∗10 were analyzed. All samples from all other genotypes were included, except a few from which not enough blood was available. The person performing

Results

Table 1 shows the NAT1 alleles which were tested in our population. The frequencies of the NAT1 genotypes and alleles detected in our population are given in Table 2aand 2b. The genotype frequencies (Table 2a) were not significantly different from the predictions based on the allele frequencies (Table 2b) according to the Hardy–Weinberg theorem. The allele frequencies were also not significantly different (tested by Fisher’s exact test) from frequencies in other large Caucasian populations

Discussion

In our study, there was no significant difference between the activity of the ∗4/∗4, ∗4/∗10, and ∗10/∗10 individuals using PABA as substrate. Since NAT1∗10 does not code for any amino acid exchange, this finding should be similarly valid for all other substrates of NAT1, in contrast to the amino acid polymorphisms which may have differential impact with different substrates. The results for NAT1∗10 described in earlier studies are conflicting. Badawi et al. [13] measured NAT1 activity using

Acknowledgements

The authors thank Mrs. Maszynski and Mrs. Pietsch for skillful performance of the polymerase chain reaction analyses. This work was partially supported by Grant 01EC9408 from the German Federal Ministry for Education, Science, Research and Technology (BMBF).

References (21)

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