Hobart ‘Bo’ Cleveland, Ph.D., Penn State University Friday, February 22nd, 2013, 3:00pm-4:30pm, McClelland Park RM 402 "Combining Intervention and Candidate Gene Research to Investigate Gene-Environment Transactions Affecting Adolescent Substance Use” Adolescent substance use is linked to concurrent risk behaviors and future life challenges. Programs designed to reduce adolescent substance use, such as school-based interventions, have been shown to help reduce substance use risk. Unfortunately, these programs vary in effect---helping some adolescents and not affecting others. To address the variability in whether and how much interventions affect adolescents’ substance use the gPROPSER study (Cleveland and Vandenbergh, M-PIs) increases the number of participants in young adult interviews and adds information on specific genetic variance among PROSPER participants. By combining candidate gene information with the prospective longitudinal randomized-community design of PROSPER, data from the gPROSPER study will be uniquely able to examine whether specific genetic variance (i.e., variability in specific alleles) moderates the impact of substance use interventions on adolescent and young adult substance use. Additional strengths of PROSPER data for GxE research include multiple waves of in-depth family process data, drawn from detailed In-Home interviews, and annual assessments of peer nominations, from which peer attribute and sociometric position variables can be computed. These characteristics will allow gPROSPER analyses to go beyond determining whether specific genes moderate intervention effects on substance use to investigate the socio-environmental processes through which such GxE transactions may operate to affect substance use. This NIDA-funded project is in its second of four years. Data presently available for analyses include adolescent in-home and in-school reports and genotypes from over 500 respondents who took part in multiple waves of detailed In-Home data collections. These respondents have been genotyped with a 318 thousand exon-coding SNP Affymetrics AXIOM array, as well as several well-studied VNTR sites (including DRD4 and 5-httlpr). The presentation will include a description of the gPROSPER design and data, challenges associated with adding candidate genes to existing studies, and findings from the initial analyses of the genotyped In-Home data. Such analyses will include initial analyses of the moderation of intervention effects on substance use by genetic variants, such as DRD4.