Pharmacogenomics of CYP2A6, CYP2B6, CYP2C19, CYP2D6, CYP3A4, CYP3A5 and MDR1 in Vietnam

Eur J Clin Pharmacol. 2009 Apr;65(4):355-63. doi: 10.1007/s00228-008-0573-8. Epub 2008 Nov 1.

Abstract

Aim: The aim of this study was to obtain pharmacogenetic data in a Vietnamese population on genes coding for proteins involved in the elimination of drugs currently used for the treatment of malaria and human immunodeficiency virus/acquired immunodeficiency syndrome.

Method: The main polymorphisms on the cytochrome P450 (CYP) genes, CYP2A6, CYP2B6, CYP2C19, CYP2D6, CYP3A4 and CYP3A5, and the multi-drug resistance 1 gene (MDR1) were genotyped in 78 healthy Vietnamese subjects. Pharmacokinetic metrics were available for CYP2A6 (coumarin), CYP2C19 (mephenytoin), CYP2D6 (metoprolol) and CYP3As (midazolam), allowing correlations with the determined genotype.

Results: In the CYP2 family, we detected alleles CYP2A6*4 (12%) and *5 (15%); CYP2B6*4 (8%), *6 (27%); CYP2C19*2 (31%) and *3 (6%); CYP2D6*4, *5, *10 (1, 8 and 44%, respectively). In the CYP3A family, CYP3A4*1B was detected at a low frequency (2%), whereas CYP3A5 *3 was detected at a frequency of 67%. The MDR1 3435T allele was present with a prevalence of 40%. Allele proportions in our cohort were compared with those reported for other Asian populations. CYP2C19 genotypes were associated to the S-4'-OH-mephenytoin/S-mephenytoin ratio quantified in plasma 4 h after intake of 100 mg mephenytoin. While CYP2D6 genotypes were partially reflected by the alpha-OH-metroprolol/metoprolol ratio in plasma 4 h after dosing, no correlation existed between midazolam plasma concentrations 4 h post-dose and CYP3A genotypes.

Conclusions: The Vietnamese subjects of our study cohort presented allele prevalences in drug-metabolising enzymes that were generally comparable with those reported in other Asian populations. Deviations were found for CYP2A6*4 compared to a Chinese population (12 vs. 5%, respectively; P = 0.023), CYP2A6*5 compared with a Korean population (15 vs. <1%, respectively; P < 0.0001), a Malaysian population (1%; P < 0.0001) and a Chinese population (1%; P < 0.0001); CYP2B6*6 compared with a Korean population (27 vs. 12%; P = 0.002) and a Japanese population (16%; P = 0.021). Pharmacokinetic metrics versus genotype analysis reinforces the view that the predictive value of certain globally common variants (e.g. CYP2D6 single nucleotide polymorphisms) should be evaluated in a population-specific manner.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics*
  • Aryl Hydrocarbon Hydroxylases / genetics*
  • Asian People / genetics*
  • Cytochrome P-450 CYP2A6
  • Cytochrome P-450 CYP2B6
  • Cytochrome P-450 CYP2C19
  • Cytochrome P-450 CYP2D6 / genetics*
  • Cytochrome P-450 CYP3A / genetics*
  • Gene Frequency
  • Genotype
  • Humans
  • Oxidoreductases, N-Demethylating / genetics*
  • Pharmacogenetics
  • Polymorphism, Genetic*
  • Vietnam

Substances

  • ABCB1 protein, human
  • ATP Binding Cassette Transporter, Subfamily B
  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Aryl Hydrocarbon Hydroxylases
  • CYP2A6 protein, human
  • CYP2B6 protein, human
  • CYP2C19 protein, human
  • CYP3A5 protein, human
  • Cytochrome P-450 CYP2A6
  • Cytochrome P-450 CYP2B6
  • Cytochrome P-450 CYP2C19
  • Cytochrome P-450 CYP2D6
  • Cytochrome P-450 CYP3A
  • CYP3A4 protein, human
  • Oxidoreductases, N-Demethylating