DOPAL is an aldehyde product of the oxidative deamination of dopamine by monoamine oxidase.[1] It can be further oxidized to 3,4-dihydroxyphenylacetic acid (DOPAC) by aldehyde dehydrogenase (ALDH) and, to a lesser extent reduced to 3,4-dihydroxyphenyl ethanol (DOPET). DOPAL is toxic to neurons.[2],[3] It can also oligomerize and precipitate alpha-synuclein, an event associated with Parkinsons disease.[2] Mice lacking cytosolic and mitochondrial forms of ALDH display increased levels of DOPAL as well as neurodegeneration and motor dysfunction characteristic of Parkinsons disease.[4]