Alcoholics with the dopamine receptor DRD2 A1 allele have lower platelet monoamine oxidase-B activity than those with the A2 allele: A preliminary study

Low platelet monoamine oxidase B (MAO-B) activity and the presence of the T aq1 Al allele of the dopamine D2 receptor (DRD2) gene have independently be en proposed as 'biological/genetic' markers for alcoholism. In the present study, the relationship between these two markers was investigated in a gro up of socially stable Caucasian middle-aged men with a mean (+/-SD) daily e thanol consumption of 85 +/- 57 g. The platelet MAO-B activity was signific antly lower in individuals with the DRD2 Al allele (n = 8), compared to tho se without it (n = 29). This relationship remained unchanged when including only subjects who fulfilled DSM-IV criteria for alcohol dependence (n = 27 ). The finding suggests that alcoholics who are carriers of the DRD2 Al all ele may have lower platelet MAO-B activity.