The gene encoding CB2 (CNR2) lies on chromosome 1p36.11. The 39.4kb gene has 2 exons and has been actively investigated for its role in osteoporosis, inflammatory responses, leukemia and certain forms of cancer. There is now mounting evidence that CB2 receptors occur in the central nervous system and that the gene is expressed in the brain [49,50]. To date, only one study has examined an association between CNR2 and substance-related behaviors. Ishiguro and colleagues [51] found an association between Q63R (glutamine to arginine), a two base pair substitution (rs2501432) and alcoholism (and also depression, see [52,53]) in a Japanese population.
