Two of the chromosome sites that were identified in the UCSF family study population for cannabis craving and cannabis withdrawal were on chromosomes 3q and 9q. These locations have been identified previously in genome scans for cannabis and other drug dependence phenotypes [see Stallings et al., 2003, 2005; Hopfer et al., 2007]. Hopfer and colleagues [2007] conducted a genome wide scan for loci influencing adolescent cannabis dependence symptoms in 324 sibling pairs from 192 families. In that study, probands (52.1% of whom were EuroAmerican, 36.5% of whom were Hispanic, and 7.8% of whom were African-American) were identified from consecutive admissions to substance abuse treatment facilities. The authors found evidence for suggestive linkage on chromosomes 3q21 (LOD = 2.61) and 9q34 (LOD = 2.57). Using the same population of adolescents, Stallings et al. [2003, 2005], conducted linkage scans for the average number of dependence symptoms, conduct disorder symptoms and a composite index of antisocial substance dependence, and also found evidence for linkage to the chromosome 9q34 region (LOD = 3.15) and 3q24-3q25 (LOD = 3.27) for the composite index. The site
