Aldehyde dehydrogenase 2 (ALDH2) is an enzyme found primarily in the liver. It plays a crucial role in the metabolism of alcohol by converting toxic aldehydes, such as acetaldehyde, into less harmful substances. This process helps protect the body from the damaging effects of alcohol consumption. Genetic variations in the ALDH2 gene can affect enzyme activity, leading to differences in alcohol tolerance among individuals. People with a less active form of ALDH2 may experience unpleasant reactions to alcohol, which can increase their risk of certain health issues, including esophageal cancer.