This 2012 human study was done by McGill University, whose researchers in Canada are at the forefront of epigenetic studies. The subject was epigenetic DNA methylation in the hippocampus of people who experienced abuse as children and who also committed suicide.

Comparisons were made with rats that were stressed in early life to identify genomic regions that are epigenetically changeable in response to a range of early life experiences.

http://www.pnas.org/content/109/Supplement_2/17266.full “Conserved epigenetic sensitivity to early life experience in the rat and human hippocampus”