Background - The molecular- and cellular-based mechanisms that contribute to the initiation and development of addiction remain to be elucidated. Estimates have suggested that 40-60 percent of the vulnerability to addiction may be attributable to genetic aberrations. Multiple chromosomal regions have been linked to addiction including those containing the dopamine transporter (DAT) and vesicular monoamine transporter (VMAT2) genes. Current efforts to understand how polymorphisms in these monoamine transporters contribute to the molecular mechanisms of addiction are severely hindered by the inability to directly interrogate neural cell types from the patients. There is great potential for patient-specific iPS cell technology to profoundly impact our understanding of human development and disease by providing genetically distinct, functional sources of human cells.