Existing OPRM1 SNP data were available from a candidate gene panel designed to interrogate nicotinic acetylcholine receptor, dopaminergic and neuropeptide candidate genes for studies of nicotine addiction and treatment related phenotypes (27–30). As described in Conti et al., genotyping of DNA samples used the GoldenGate™ assay (Illumina, San Diego, CA), with quality control procedures that included automated sample handling protocols and the inclusion of replicate DNA samples to aid in identifying genotyping errors (29). The online databases dbSNP (31) and Genewindow (32) were used to assign chromosome position and genomic annotation for OPRM1 SNPs. The program HAPLOVIEW (33) was employed to examine the extent of linkage disequilibrium (LD) between pairs of OPRM1 SNPs as well as to determine the haplotype block structure within the SMOFAM sample. Blocks were defined using the criteria proposed by Gabriel et al (34). The tagging SNP selection program Tagger (35) was used to select a subset of 21 SNPs representing the genetic information contained in the 46 OPRM1 SNPs genotyped in the SMOFAM sample.
