The question of what to measure is crucial. As discussed above, epigenetic modifications involve DNA methylation or alteration of chromatin structure that either facilitates or impedes access to DNA by transcription factors and their associated complexes, ultimately modulating gene expression.[6] However, some studies have only measured epigenetic modification in the form of DNA methylation or histone modification,[27] neglecting to measure gene expression profiles in the form of RNA or protein gene products, assuming rather, that epigenetic modification should imply concomitant changes in gene expression. However, this assumption is not always met—and in some circumstances, epigenetic changes may not be accompanied by suspected alterations to gene expression.[45] In this way, directly measuring epigenetic modification without also measuring changes in gene expression profiles is inappropriate.
