The dopamine D(3) receptor gene (DRD3) is a candidate for a number of psychiatric conditions including schizophrenia, bipolar disorder and alcohol and drug abuse.
This hypothesis is consistent with the role of DRD3 in mediating responses to drugs of abuse in animals and the association of homozygosity at the Bal I polymorphism with drug abuse in schizophrenic patients (see companion article by Krebs et al).