title: CYP2C19 genotype and phenotype determined by omeprazole in a Korean population.
abstract: Omeprazole (20 mg orally) was given to 103 healthy Korean subjects and blood was taken 3 h after administration. The plasma concentration ratio of omeprazole and hydroxyomeprazole, used as an index of CYP2C19 activity, was bimodally distributed. Thirteen subjects (12.6%) were identified as poor metabolizers (PMs) with an omeprazole hydroxylation ratio of 6.95 or higher. Among the 206 CYP2C19 alleles, CYP2C19*2 and CYP2C19*3 were found in 43 alleles (21%) and 24 alleles (12%), respectively. Twelve subjects (12%) carried two defect alleles (*2/*2, *2/*3 or *3/*3), 43 subjects (42%) were heterozygous for a mutated (*2 or *3) and a wild type (*1) allele, and the remaining 48 subjects (47%) were homozygous for the wild type allele. The distributions of the metabolic ratio between these three genotype groups were significantly different (Kruskal-Wallis test: p < 0.0001). The genotypes of 19 additional Korean PMs has been identified in a previous mephenytoin study. From a total of 32 PMs, 31 were genotypically PMs by analysis of the CYP2C19*2 and *3 alleles and only one PM subject was found to be heterozygous for the *1 and *2 alleles. At present it cannot be judged whether this subject has a defective allele with a so-far unidentified mutation or a true wild type allele. We thus confirm a high incidence (12.6%) of PMs of omeprazole in Koreans and of the 32 Korean PMs 97% could be identified by the genotype analysis.
authors.affiliation: Department of Medical Laboratory Sciences and Technology, Karolinska Institute, Huddinge Hospital, Sweden.
authors.forename: H K
authors.initials: HK
authors.lastname: Roh
authors.forename: M L
authors.initials: ML
authors.lastname: Dahl
authors.forename: G
authors.initials: G
authors.lastname: Tybring
authors.forename: H
authors.initials: H
authors.lastname: Yamada
authors.forename: Y N
authors.initials: YN
authors.lastname: Cha
authors.forename: L
authors.initials: L
authors.lastname: Bertilsson
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000483:Alleles; D001189:Aryl Hydrocarbon Hydroxylases; D065731:Cytochrome P-450 CYP2C19; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007723:Korea; D008297:Male; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D009853:Omeprazole / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics; D010641:Phenotype
chemical_list: D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D009853:Omeprazole