A Pharmacogenetic Study of Pregnane X Receptor (NR1I2) in Han Chinese
The pregnane X receptor (PXR/NR1I2) gene is a critical transcriptional regulator of a number of important drug metabolizing enzymes and transporters. This study was undertaken to determine the frequencies of single nucleotide polymorphisms (SNPs) and haplotypes and to detect yet unknown SNPs in the NR1I2 gene in 210 unrelated healthy Han Chinese in comparison with other ethnic groups. We also characterized the functional impact of two SNPs, -24622A>T in the 5'-untranslated region and -24446C>A in exon 1 of NR1I2, by constructing three recombinants and monitoring promoter activity using the dual luciferase reporter gene assay. Genomic DNA was isolated from peripheral leukocytes and subjected to polymerase chain reaction (PCR) amplification, followed by direct DNA sequencing. Sixteen SNPs in NR1I2 with frequencies of 0.3-90.3% were found in Han Chinese, two of which (-25439A>G in the 5'-untranslated region and 7637C>T in intron 5) are previously unknown. The mutant allelic frequencies varied from 0.3% to 90.3%. Most of the detected SNPs were located in introns. A total of 15 linkage disequilibriums were detected; and positive linkage disequilibriums were found between -24381A>C in exon 1 and -24113G>A in intron 1, and 252A>G in intron 2 and 275A>G in intron 2 (p2 = 1, P<0.001). A total of 42 haplotypes were inferred and the two most frequent haplotypes were H1 (TCAGGGGCCACC) and H2 (CCGAAAACTAAT) with a frequency of 15.1%. The activity of the recombinants with alleles containing the -24622A>T in the 5'-untranslated region or -24446C>A in exon 1 was 30-40% higher than that in the wild-type (reference genotype). These results indicate that there are marked ethnic differences in the frequency between Han Chinese and other ethnic groups and that alleles with -24622A>T in the 5'-untranslated region and - 24446C>A in exon 1 of the NR1I2 gene result in an increased activity compared to the wild-type. Further studies are warranted to explore the clinical and toxicological impact of SNPs and haplotypes of NR1I2 in various ethnic groups.
No Supplementary Data
No Article Media
Document Type: Research Article
Publication date: December 1, 2007
More about this publication?
- Current Drug Metabolism aims to cover all the latest and outstanding developments in drug metabolism and disposition. The journal serves as an international forum for the publication of timely reviews in drug metabolism. Current Drug Metabolism is an essential journal for academic, clinical, government and pharmaceutical scientists who wish to be kept informed and up-to-date with the latest and most important developments. The journal covers the following areas:
In vitro systems including CYP-450; enzyme induction and inhibition; drug-drug interactions and enzyme kinetics; pharmacokinetics, toxicokinetics, species scaling and extrapolations; P-glycoprotein and transport carriers; target organ toxicity and interindividual variability; drug metabolism and disposition studies; extrahepatic metabolism; phase I and phase II metabolism; recent developments for the identification of drug metabolites and adducts.
- Editorial Board
- Information for Authors
- Subscribe to this Title
- Ingenta Connect is not responsible for the content or availability of external websites