For OPRM1 genotyping, approximately the first 100 subjects were genotyped in both our lab and that of David Goldman (Neurogenetics Lab at NIAAA) with 100% agreement. Four samples each representing asn40 homozygotes as well as asp40asn hetero and asp40asp homozygotes, with identical identification in both labs were used as “positive controls” for all subsequent Taqman assays.