This is a more targeted way to examine the extent to which SNPs in a gene that has been selected for its biological relevance are associated with the trait of interest. Data may be either family-based or case-control [24]. For cannabis use disorders, we focus on:Genes that are specific to the endogenous cannabinoid system and hence likely to be specific to the etiology of cannabis use disorders;Biologically relevant genes that are largely non-specific and have been shortlisted for their association with other forms of substance abuse;
