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BioMed Research International
Volume 2015, Article ID 123484, 23 pages
http://dx.doi.org/10.1155/2015/123484
Review Article

Environmental Impact on DNA Methylation in the Germline: State of the Art and Gaps of Knowledge

Laboratory of Toxicology, Technical Unit of Radiation Biology and Human Health, CR Casaccia, ENEA, Via Anguillarese 301, 00123 Rome, Italy

Received 14 January 2015; Accepted 3 May 2015

Academic Editor: Heide Schatten

Copyright © 2015 Francesca Pacchierotti and Marcello Spanò. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The epigenome consists of chemical changes in DNA and chromatin that without modifying the DNA sequence modulate gene expression and cellular phenotype. The epigenome is highly plastic and reacts to changing external conditions with modifications that can be inherited to daughter cells and across generations. Whereas this innate plasticity allows for adaptation to a changing environment, it also implies the potential of epigenetic derailment leading to so-called epimutations. DNA methylation is the most studied epigenetic mark. DNA methylation changes have been associated with cancer, infertility, cardiovascular, respiratory, metabolic, immunologic, and neurodegenerative pathologies. Experiments in rodents demonstrate that exposure to a variety of chemical stressors, occurring during the prenatal or the adult life, may induce DNA methylation changes in germ cells, which may be transmitted across generations with phenotypic consequences. An increasing number of human biomonitoring studies show environmentally related DNA methylation changes mainly in blood leukocytes, whereas very few data have been so far collected on possible epigenetic changes induced in the germline, even by the analysis of easily accessible sperm. In this paper, we review the state of the art on factors impinging on DNA methylation in the germline, highlight gaps of knowledge, and propose priorities for future studies.