CYP2A7 is a hepatic cytochrome P450 monooxygenase involved in the oxidative metabolism of xenobiotics, steroids, and fatty acids through NADPH-dependent electron transport. Unlike the highly homologous CYP2A6, CYP2A7 exhibits minimal enzymatic activity toward standard substrates; it does not metabolize nicotine, coumarin, or 7-ethoxycoumarin 1. However, CYP2A7 can hydroxylate diclofenac and acts on certain proluciferin probe substrates 1. The enzyme exists in multiple genetic variants: the reference CYP2A7*1 sequence and a wild-type variant (CYP2A7-WT) containing four common missense mutations (MAF>0.5) 1, plus polymorphic alleles with CYP2A6-derived 3'-UTR sequences 2. Alternative splicing generates a shorter 44 kDa isoform lacking enzymatic activity 3. CYP2A7 is structurally similar to CYP2A6, sharing ~90% sequence identity, enabling genetic recombination events such as the CYP2A6*12 hybrid allele 4. While CYP2A7's specific metabolic contributions remain largely undefined, its genetic polymorphisms can confound CYP2A6 genotyping 2. Chromosome 19 deletions involving CYP2A7 have been associated with altered chr19 architecture and dysregulated gene expression in familial colorectal cancer patients 5, suggesting potential roles in disease pathogenesis beyond drug metabolism.