Genome-wide association studies and candidate gene studies have identified SNPs near AHR target genes that are significantly associated with AHR-regulated phenotypes, such as cigarette smoking (AHRR) [64], psoriasis (CYP1A1) [17], warfarin response (CYP1A1) [65], hepatocellular carcinoma (CYP1A1) [66], atherosclerosis (CYP1A1 and AHRR) [57,58,67,68,69], coffee consumption (CYP1A1 and CYP1A2) [63], and systemic lupus erythematous (CYP1A1) [17]. Here, CYP1A1 is linked to hepatocellular carcinoma.