These investigators observed a lod score of 4.17 at 92 cM. Because this location is not within the 1-lod support interval for the locus we observed on the same chromosome, it likely represents a different risk gene. We previously reported linkage results for cocaine and opioid dependence, and cocaine-induced paranoia, in parts of the same AA sample reported upon here (23, 24). As we have reported previously (29), the correlations for diagnoses of alcohol, opioid, and cocaine dependence in this sample are not high; they range between 0.067 (cocaine vs opioid dependence) and 0.295 (cocaine dependence vs AD). Thus, linkage analyses of these traits capture different information. The chromosomal region contains numerous genes potentially relevant to alcohol dependence, of which perhaps the most immediately interesting are the genes encoding synaptic vesicular amine transporter, or VMAT 2 (SLC18A2) (which is however distal to the peak signal); and serotonin 7 receptor (HTR7).
