The cytochrome P450 (CYP) enzymes are a class of heme-containing enzymes involved in phase 1 metabolism of which cytochrome P450 2E1 (CYP2E1) metabolizes many xenobiotics and procarcinogens, and thus they play an important role in the activation of AOM in vivo [45]. This evidence concerns the gene CYP2E1 and infectious otitis media.