What Does The A1 Gene Do?

What Does The A1 Gene Do? The A1 allele of the human D2 dopamine receptor gene is associated with increased activity of striatal L-amino acid decarboxylase in healthy subjects. Pharmacogenet Genomics. What is the DRD2 A1 gene? The TaqIA D2 dopamine receptor (DRD2) minor (A1) allele was first associated with severe alcoholism a decade ago.