The Dopamine D2 Receptor Gene and Alcoholism

To the Editor. — Two JAMA reports differ in describing the association between a D₂dopamine receptor gene allele and alcoholism. Blum et al¹found that the Al allele of the D₂gene was present in a significantly higher percentage of 35 alcoholics (69%) than in 35 nonalcoholic controls (20%). Diagnoses were made post mortem; therefore, limited descriptive information was available. Bolos et al²assessed the gene's distribution in a group of 40 white alcoholics (38% Al) and 127 racially matched controls (30% Al) but found no evidence for an association between the D₂receptor allele and alcoholism. There is a limitation in the second study. Although Bolos et al conducted thorough clinical assessments of alcoholic subjects, they present no characteristics (except race) of their "control" subjects. Their control subjects could be alcoholics (or have other relevant psychiatric diagnoses, such as affective disorder). Further, the