We developed a protocol for genetic analyses of opioid-related craving using Polygenic Scores (PGSs). After identifying a set of genes for analysis, SNPs were selected from the genes, and the set of SNPs was reduced based on linkage disequilibrium, and tested for association of the alleles of each SNP with craving. The associated alleles were summed to create the PGS.  We are now ready to apply the PGS to an independent data set.