title: Search for the molecular basis of ultra-rapid CYP2C9-catalysed metabolism: relationship between SNP IVS8-109A>T and the losartan metabolism phenotype in Swedes.
abstract: OBJECTIVE
  To search for a relationship between ultra-rapid metabolism catalysed by cytochrome P450 2C9 (CYP2C9) and its genotypes.
  
  
  METHODS
  DNA from a Swedish ultra-rapid metaboliser patient [losartan metabolic ratio (MR) <0.13] and three healthy Swedes with normal CYP2C9 activity and a MR of about 1 were assessed for variation in the CYP2C9 gene. Direct DNA sequencing was performed for all exons and exon-intron junctions and also for -2100 bp of the 5′-flanking regions of the CYP2C9 gene. This analysis revealed four intronic mutations [single nucleotide polymorphisms (SNPs) 1-4] in the three samples with normal MR while no variation was observed in the ultra-rapid metaboliser. PCR/restriction fragment length polymorphism and allele-specific PCR methods were subsequently developed to screen 85 Swedes and 128 Koreans without CYP2C9*2 or *3.
  
  
  RESULTS
  We found a significant relationship between SNP 4 (IVS8-109A>T) and CYP2C9 activity (χ²-test, p=0.011) in the Swedes. Twenty Swedes with the lowest MR were compared with 20 Swedes with the highest MR, revealing a strong association (p00.001) between SNP4 and higher MR. For homozygous SNP 1 (IVS1+83T>C), SNP 2 (IVS2+73T>C), and SNP 3 (IVS6+95A>G), no phenotype and genotype relationships were found, but theMRwas generally higher among the Swedes compared to the Koreans (Mann-Whitney test, p<0.05).
  
  
  CONCLUSIONS
  We found that the SNP 4 IVS8-109T allele is associated with a higher CYP2C9 MR in healthy Swedish subjects, but further investigations need to be carried out to establish a molecular explanation for ultra-rapid CYP2C9- catalysed metabolism. Haplotype based on SNPs 1-4 did not seem to contribute to variation in the MR of the Korean subjects nor play a role in determining the MR of the Swedish ones.
authors.affiliation: Division of Clinical Pharmacology, Department of Laboratory Medicine, Karolinska Institutet-Karolinska University Hospital, Huddinge 141 86 Stockholm, Sweden. fazleen@salam.uitm.edu.my
authors.forename: Fazleen H M
authors.initials: FH
authors.lastname: Hatta
authors.forename: Lay Kek
authors.initials: LK
authors.lastname: Teh
authors.forename: Anders
authors.initials: A
authors.lastname: Helldén
authors.forename: Karin Engström
authors.initials: KE
authors.lastname: Hellgren
authors.forename: Hyung-Keun
authors.initials: HK
authors.lastname: Roh
authors.forename: Mohd Zaki
authors.initials: MZ
authors.lastname: Salleh
authors.forename: Eleni
authors.initials: E
authors.lastname: Aklillu
authors.forename: Leif
authors.initials: L
authors.lastname: Bertilsson
mesh_terms: D000328:Adult; D000483:Alleles; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000378:metabolism*; D044466:Asian People; D065729:Cytochrome P-450 CYP2C9; D003627:Data Interpretation, Statistical; D005091:Exons / Q000235:genetics; D006239:Haplotypes; D006801:Humans; D007438:Introns / Q000235:genetics; D019808:Losartan / Q000378:metabolism* / Q000493:pharmacokinetics; D008297:Male; D050216:Metabolic Detoxication, Phase I; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D056910:Republic of Korea; D013548:Sweden; D044465:White People; D055815:Young Adult
chemical_list: C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; D019808:Losartan