In summary, variations in the GABRA2 gene are associated with differences in electrophysiological measures (e.g., the P300 wave) that are indicative of vulnerability to a variety of addictions. In addition, several association studies have implicated GABRA2 in alcohol dependence. Finally, the findings of one association study and several suggestive linkage studies have implicated variations in the GABAB2 gene in nicotine dependence. Because GABRA2 and GABAB2 have similar functions, it is possible that these and other genes encoding GABA receptor components may contribute to a variety of addictive disorders. Furthermore, the role of GABRA2 in determining P300 brain waves suggests that electrophysiological studies may help to identify and elucidate the function of variants within this family of genes that are associated with an increased risk of dependence on alcohol and other drugs.
