although a recent model shows a smaller contribution (Chi et al., 2018). ADH7 is the only ADH enzyme not expressed in liver; it contributes to ethanol oxidation and local generation of acetaldehyde primarily in the stomach and esophagus. ADH5 is ubiquitously expressed; although it doesn’t make a major contribution to ethanol oxidation in liver, it can contribute to metabolism in other tissues, including the GI tract and brain, and thereby generate acetaldehyde locally. ADH6 has never been isolated from human tissue, although its RNA is present; computational modeling suggests it is likely to be both highly unstable and inactive (Ostberg et al., 2016) and therefore not likely to impact alcohol metabolism.
