Recently, in an European American (EA) sample, we observed that the interaction between two variants of CNR1 significantly increased risk for drug dependence (DD), which included CD and/or OD (Zuo et al 2007). The present study further investigated the association between CNR1 and CD. Moreover, a related phenotype, i.e., cocaine induced paranoia (CIP), was included to increase the information gained from the present study (Gelernter et al 2005). Genetic variants in the dopamine transporter gene (DAT1) and the dopamine β-hydroxylase gene (DBH) were reported to confer genetic vulnerability to CIP (Cubells et al 2000; Gelernter et al 1994; Kalayasiri et al 2007). We have recently reported several additional associations based on a low-density genomewide association scan (Yu et al 2008).
