In the present study we set out to replicate the finding of Moyer et al. by genotyping rs1076560 in a large number of cocaine addicts and controls, in populations of European and African American ancestry. Furthermore, as animal studies have found that mice lacking the D2L receptor will not develop conditioned place preference for morphine, or place aversion to naloxone precipitated morphine withdrawal (Smith et al., 2002), we were also interested in examining the role of rs1076560 in opioid dependence. Therefore, association analyses of rs1076560 were also carried out in groups of opioid dependent individuals and controls of both European and African American ancestry.
