Cannabis is the most widely use illicit drug. A genome-wide linkage analysis of cannabis dependence and related phenotypes in individuals from the UCSF Family Alcoholism Study identified genome-wide significant linkage (LOD score of 3 or higher) for cannabis craving and withdrawal symptoms for regions on human chromosomes 1, 3, 6, 7, and 9; no evidence for linkage with cannabis dependence reached genome-wide significant (38). Loci on human chromosomes 3 (3q21) and 9 (9q34), which are close to the regions linked to cannabis withdrawal in the UCSF study, were also suggested to influence cannabis-dependence symptoms in adolescents who participated in a Colorado Center on Antisocial Drug Dependence study (65). A Native American community study detected genome-wide significant linkage with the severe cannabis use/antisocial subtype on human chromosomes 16 (LOD score of 4.4) and 19 (LOD score of 6.4) (37).
