Glutamatergic and GABAergic susceptibility loci for heroin and cocaine addiction in subjects of African and European ancestry.

Background: Drug addiction, a leading health problem, is a chronic brain disease with a significant genetic component. Animal models and clinical studies established the involvement of glutamate and GABA neurotransmission in drug addiction. This study was designed to assess if 258 variants in 27 genes of these systems contribute to the vulnerability to develop drug addiction.

Methods: Four independent analyses were conducted in a sample of 1860 subjects divided according to drug of abuse (heroin or cocaine) and ancestry (African and European).

Results: A total of 11 SNPs in eight genes showed nominally significant associations (P<0.01) with heroin and/or cocaine addiction in one or both ancestral groups but the associations did not survive correction for multiple testing. Of these SNPs, the GAD1 upstream SNP rs1978340 is potentially functional as it was shown to affect GABA concentrations in the cingulate cortex. In addition, SNPs GABRB3 rs7165224; DBI rs12613135; GAD1 SNPs rs2058725, rs1978340, rs2241164; and GRIN2A rs1650420 were previously reported in associations with drug addiction or related phenotypes.

Conclusions: The study supports the involvement of genetic variation in the glutamatergic and GABAergic systems in drug addiction with partial overlap in susceptibility loci between cocaine and heroin addiction.