This relationship is clearly observed in Japanese Americans due to the high prevalence of low or no-activity CYP2A6 alleles.7 However, decreased CYP2A6 activity may influence smoking and carcinogen exposure in any smoker, and the relationship of nicotine metabolism and CYP2A6 genotype to the lung cancer risk of smokers of European descent was recently established in the Transdisciplinary Research in Cancer of the Lung consortium genome-wide association study data set.13 The gene discussed is CYP2A6; the disease is lung cancer.