In summary, the literature on potential epigenetic biomarkers for cannabis use disorders and exposure are extremely limited and, in contrast to smoking, there do not appear to be any loci which meet the criteria outlined above for potential clinical translation. There was a single significant association found in one study between CB1 promoter methylation and cannabis dependence. Although the magnitude of change in methylation at this locus between cannabis-dependent subjects and non-smokers was appreciable at 26%, the difference between cannabis-dependent subjects and cigarette smokers was much more modest at less than 5%, casting doubt on the potential applicability of this finding. Nonetheless, there is a great deal of potential for the development of epigenetic biomarkers for cannabis use simply because no studies have been done using the larger array-based platforms to look more broadly for associations. There is some possibility that unique signatures may be found, particularly if studies are done with careful clinical characterization and confirmation of exposure via existing biomarkers such as ELISA for THC metabolites. It remains to be seen if these studies will be able to
