Associations between polymorphisms in the AHR and CYP1A1-CYP1A2 gene regions and habitual caffeine consumption

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-CY1PA2) 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. Design: 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. Conclusion: 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. Am J Clin Nutr 2012;96:665-71.