To address the issue of cost, less expensive methods of assessing methylation patterns at loci that have been well-validated should be investigated. For example, quantitative PCR may be quite inexpensive and suitable for well-characterized loci such as AHRR. However, as the expense of methylome-wide arrays continues to fall, routine screening at a large number of loci may become more commonplace. If so, best practices for interpretation will be needed, as experience with rise of genetic testing marketed to individual consumers suggests there is great potential for misinterpretation of findings. It is also possible that the technology to assay other epigenetic biomarkers such as histone modifications may become less expensive and future studies may more routinely use these technologies to add to our understanding of the total picture of epigenetic regulation in the setting of substance use.
