title: Pharmacogenetics of CYP2C19 genetic polymorphism on clopidogrel response in patients with ischemic stroke from Saudi Arabia.
abstract: To elucidate the degree of genetic polymorphisms CYP2C19 (CYP2C19*2, CYP2C19*3) of key drug metabolizing enzymes on the antiplatelet effect of clopidogrel response in patients with acute ischemic stroke from Saudi Arabia.
  
  
  
  A case-control study carried out at Neurology Clinics at Asser Central Hospital, Abha, Kingdom of Saudi Arabia from October 2015 to January 2016 and included 25 stroke patients responding to clopidogrel therapy and 25 stroke patients non responding to clopidogrel monotherapy. After obtaining their informed consent, the blood samples were collected and genotyped for CYP2C19 polymorphisms by the polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP Method). Allele frequencies were derived from genotypic data and platelet aggregation was measured using multiple electrode aggregometry on the multiplate analyser. Chi Square tests, p-values, odds ratio (OR) and corresponding confidence intervals were calculated for each polymorphism.
  
  
  
  The CYP2C19*2 (681G>A) and CYP2C19*3 (636 G>A) polymorphism were seen to be in Hardy-Weinberg equilibrium and showed significant allelic and genotypic association between responders and non-responders to clopidogrel (p<0.01). The CYP2C19*2: allelic chi-square=21.49, p=0.000036, OR=5.52 (2.42-12.83); Genotypic Chi-square=10.27, p=0.001, OR=7.88 (1.78-9.73). The CYP2C19*3: Allelic chi-square=11.66, p=0.0006, OR=3.45 (1.57-7.70); genotypic chi-square=4.37, p=0.036, OR=3.69 (0.90-5.81). The variant allele (homozygous and homozygous Mutant) showed significant influence on platelet inhibition and the antiplatelet effect of clopidogrel in ischemic stroke.
  
  
  
  Our findings provide certain evidence on the genetic effect of CYP2C19 on clopidogrel responsiveness in stroke patients from Saudi Arabia.
authors.affiliation: Assistant Professor of Neurology, Department of Neurosciences, College of Medicine, King Khalid University, Abha, Kingdom of Saudi Arabia.
authors.forename: Adel A
authors.initials: AA
authors.lastname: Alhazzani
authors.forename: Murali
authors.initials: M
authors.lastname: Munisamy
authors.forename: Gauthaman
authors.initials: G
authors.lastname: Karunakaran
mesh_terms: D016022:Case-Control Studies; D000077144:Clopidogrel / Q000494:pharmacology* / Q000627:therapeutic use; D065731:Cytochrome P-450 CYP2C19 / Q000235:genetics*; D004351:Drug Resistance / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D011110:Polymorphism, Genetic / Q000235:genetics; D012529:Saudi Arabia; D020521:Stroke / Q000188:drug therapy* / Q000235:genetics*
chemical_list: D000077144:Clopidogrel; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19