We conclude that genetic variation at or near the GABRA2 locus significantly affects vulnerability not only to AD, but to other forms of substance use including ND and CD, and that the effects may be sex dependent.
Therefore, we genotyped 516 individuals from the Iowa Adoption Studies, a large longitudinal case and control adoption study of substance use, at 39 single nucleotide polymorphisms encompassing the GABRA2 locus and analyzed them with respect to their lifetime history of three common forms of substance use dependence [alcohol dependence (AD), nicotine dependence (ND), and cannabis dependence (CD)] in the Iowa Adoption Studies and relevant exposure variables.