promoter region of Htr3a in nine reward-related brain regions of mice and showed a wide range of alterations in the methylation of this gene in different brain regions.96 These results indicate that DNA methylation can be tissue-specific. A small human subject study using blood and brain tissue samples from two men and one woman revealed that tissue-specific epigenetic variation outweighed between-individual epigenetic variation.97 Therefore, the identification of DNA methylomic changes in different brain regions of AUD subjects is an important aim of our future studies in order to have a better understanding of the particular function of specific brain regions involved in AUD development.
