A study that examined methamphetamine dependence (G. R. Uhl, Drgon, Liu, et al., 2008) also found a substantial overlap of positively associated genes with studies that examined drug dependence (defined by addiction to one or more addictive substances). Like those studies, genes for cell adhesion molecules, enzymes, transcriptional regulation, cell structure and RNA, DNA and protein handling/modifying genes were overrepresented. This included Csmd1 and Cdh13, genes which are among the most commonly identified genes in GWAS for drug dependence (see Table 2).
