In the study, subjects in the medium and high tertiles of CYP2A6 activity had an increased risk of colorectal cancer compared with subjects with low activity.[31] In our study, in the case of CYP2A13, it is observed that individuals with blood type A have 21.60% with the Wild genotype, 17.33% with Heterozygous, and 22.22% with the Mutant genotype. Here, CYP2A6 is linked to colorectal cancer.