The goal of the Pharmacogenetics CORE of this Medications Development Unit Center (MDU) is to integrate molecular genetics into the design and execution of clinical trials of pharmacotherapies for cocaine dependence. We will employ prospective genotyping to stratify participants by genotype at the DBH locus in Project 1 and at the serotonin transporter locus in Project 2. This CORE has five Specific Aims. (1) In Project 1we will stratify prospective subjects bygenotype at a functional promoter polymorphism regulating levels of dopamine beta hydroxylase (DBH) and then enter them into a placebo controlled randomized clinical trial of disulfiram for cocaine dependence. (2) In Project 2 we will stratify prospective subjects by genotype at a functional promoter polymorphism regulating 5-HTTPLR and then enter them into a placebo controlled randomized clinical trial of sertraline for cocaine dependence. (3) For both Projects 1 and 2 we will identify novel single nucleotide polymorphisms (SNPs) in the GAT-1 gene (SLC6A12), which encodes the GABA transporter protein, GAT-1. The GAT-1 is the therapeutic target of tiagabine, which is compared to placebo in both Projects. We will test for an association between GAT-1 haplotypes and response to tiagabine. (4) We will establish an infrastructure for genotyping known non-synonymous SNPs at GAD-65 and GAD-67, and at the 5-HTTPLR. (5) We will provide technical consultation and support for genotype- based analyses in the current MDUand for other NIDA-sponsored trials for substance-use treatments at Yale. The facilities supported by this CORE will consult on genetic approaches (including statistical genetics) to clinical trials by all the faculty in the Division of SubstanceAbuse. The integration of molecular genetics and clinical pharmacology promises to advance the field of substance abuse treatment by generating innovative hypotheses and introducing new genetic and neuro-proteinomic methodologies as they evolve for other types of medical disorders besides substanceabuse.