title: Associations between polymorphisms in the AHR and CYP1A1-CYP1A2 gene regions and habitual caffeine consumption.
abstract: BACKGROUND
  Recent genome-wide association studies (GWASs) from populations of European descent identified single nucleotide polymorphisms (SNPs) in aryl-hydrocarbon receptor (AHR) and cytochrome P450 1A1 and 1A2 (CYP1A1-CYP1A2) genes that are associated with habitual caffeine and coffee consumption.
  
  
  OBJECTIVE
  We examined whether these SNPs (AHR: rs6968865 and rs4410790; CYP1A1-CYP1A2: rs2472297 and rs2470893) and 6 additional tag SNPs in the AHR gene were associated with habitual caffeine consumption in a Costa Rican population.
  
  
  METHODS
  Subjects were from a case-control study of gene-diet interactions and myocardial infarction. Subjects with hypertension or missing information on smoking, caffeine intake, or genotype were excluded. Subjects were genotyped by using polymerase chain reaction with mass spectrometry-based detection, and caffeine intake was assessed by using a validated food-frequency questionnaire.
  
  
  RESULTS
  Compared with subjects who consumed <100 mg caffeine/d, subjects who consumed >400 mg caffeine/d were more likely to be carriers of the T, C, or T allele for rs6968865, rs4410790, and rs2472297, respectively. The corresponding ORs and 95% CIs were 1.41 (1.03, 1.93), 1.41 (1.04, 1.92), and 1.55 (1.01, 2.36). Multivariate-adjusted ORs (95% CIs) for rs6968865 were 1.44 (1.03, 2.00) for all subjects, 1.75 (1.16, 2.65) for nonsmokers, 1.15 (0.58, 2.30) for current smokers, 2.42 (1.45, 4.04) for subjects >57 y old, and 1.00 (0.65, 1.56) for subjects ≤57 y old. A similar effect modification was observed for rs4410790 but not for rs2472297.
  
  
  CONCLUSIONS
  Our findings show that previous associations between SNPs in AHR and CYP1A1-CYP1A2 and caffeine and coffee consumption from GWASs in European populations are also observed in an ethnically distinct Costa Rican population, but age and smoking are important effect modifiers.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, Canada.
authors.forename: Andrea R
authors.initials: AR
authors.lastname: Josse
authors.forename: Laura A
authors.initials: LA
authors.lastname: Da Costa
authors.forename: Hannia
authors.initials: H
authors.lastname: Campos
authors.forename: Ahmed
authors.initials: A
authors.lastname: El-Sohemy
mesh_terms: D000367:Age Factors; D000368:Aged; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D002110:Caffeine / Q000008:administration & dosage* / Q000378:metabolism; D016022:Case-Control Studies; D003069:Coffee; D003364:Costa Rica; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics* / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics* / Q000378:metabolism; D005247:Feeding Behavior / Q000208:ethnology; D005260:Female; D056726:Genetic Association Studies; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D054647:Nutrigenomics / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics* / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects / Q000378:metabolism; D011795:Surveys and Questionnaires
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002110:Caffeine; D003069:Coffee; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2; D018336:Receptors, Aryl Hydrocarbon; C111235:AHR protein, human; C569463:CYP1A1 protein, human; C504573:CYP1A2 protein, human