title: The influence of the CYP2C19*10 allele on clopidogrel activation and CYP2C19*2 genotyping.
abstract: OBJECTIVE
  The polymorphic hepatic enzyme CYP2C19 catalyzes the metabolism of clinically important drugs such as clopidogrel, proton-pump inhibitors, and others and clinical pharmacogenetic testing for clopidogrel is increasingly common. The CYP2C19*10 single-nucleotide polymorphism (SNP) is located 1 bp upstream the CYP2C19*2 SNP. Despite the low frequency of the CYP2C19*10 allele, its impact on metabolism of CYP2C19 substrates and CYP2C19*2 genotyping makes it an important SNP to consider for pharmacogenetic testing of CYP2C19. However, the effect of the CYP2C19*10 allele on clopidogrel metabolism has not been explored to date.
  
  
  METHODS
  We measured the enzymatic activity of the CYP2C19.10 protein against clopidogrel. DNA samples from two clinical studies were genotyped for CYP2C19*2 and *10 by pyrosequencing genotyping method.
  
  
  RESULTS
  The catalytic activity of CYP2C19.10 in the biotransformation of clopidogrel and 2-oxo-clopidogrel was significantly decreased relative to the wild-type CYP2C19.1B. We also reported that the CYP2C19*10 SNP interferes with the CYP2C19*2 TaqMan genotyping assay, resulting in miscalling of CYP2C19*10/*2 as CYP2C19*2/*2.
  
  
  CONCLUSIONS
  Our data provide evidence that CYP2C19.10 variant partially metabolizes clopidogrel and 2-oxo-clopidogrel, and the presence of CYP2C19*10 allele affects the CY2C19*2 TaqMan genotyping assay and results in misclassification of CYP2C19*10/*2 as CYP2C19*2/*2.
authors.affiliation: aDepartment of Pharmacotherapy and Translational Research, Center for Pharmacogenomics, University of Florida College of Pharmacy, Gainesville, Florida bDepartment of Clinical, Social, and Administrative Sciences, University of Michigan College of Pharmacy, Ann Arbor, Michigan, USA cKey Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing, People's Republic of China dNational Institute of Environmental Health Science, Research Triangle Park, North Carolina, USA.
authors.forename: Taimour Y
authors.initials: TY
authors.lastname: Langaee
authors.forename: Hao-Jie
authors.initials: HJ
authors.lastname: Zhu
authors.forename: Xinwen
authors.initials: X
authors.lastname: Wang
authors.forename: Nihal
authors.initials: N
authors.lastname: El Rouby
authors.forename: John S
authors.initials: JS
authors.lastname: Markowitz
authors.forename: Joyce A
authors.initials: JA
authors.lastname: Goldstein
authors.forename: Julie A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000483:Alleles; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D002384:Catalysis; D002853:Chromatography, Liquid; D000077144:Clopidogrel; D065731:Cytochrome P-450 CYP2C19; D005838:Genotype; D006801:Humans; D007700:Kinetics; D008617:Mephenytoin / Q000378:metabolism; D009853:Omeprazole / Q000378:metabolism; D010597:Pharmacogenetics; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D053719:Tandem Mass Spectrometry; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: C540904:2-oxo-clopidogrel; D000077144:Clopidogrel; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D009853:Omeprazole; D013988:Ticlopidine; D008617:Mephenytoin