Workshop Report 30

What are epigenetic studies? Technical aspects and data interpretation to achieve confidence in epigenetic studies (human epidemiology and animal-based studies)

John Greally

Clinical Genomicist and Professor of Genetics, Paediatrics and Medicine, 
Albert Einstein College of Medicine,
New York, USA

The presentation by Professor Greally explored epigenetic heritability, the epigenome-wide association study, cellular models of epigenetic perturbations and study design recommendations. He defined the modern use of the term epigenetics as “heritable information governing a cell state unrelated to DNA sequence variability, or information that can be inherited from a parent cell that is not encoded in the DNA sequence”. He went on to discuss how and why, although numerous studies have been attempting to test how toxic exposures during pregnancy affect the epigenome of the offspring, these epigenome-wide association studies (EWAS) are now appreciated to be poorly interpretable (Greally et al, 2013). Indeed, the 2012 OECD review concluded that studies to date were not informative and recommended the need for definitive studies.
Given that EWAS are rapidly increasing in number and scope, it makes sense to develop guidance to ensure that future EWAS are rigorous and allow high confidence in their findings. Professor Greally went on to discuss the elements that should be included in future EWAS in order to increase understanding into the epigenetic effects of exposure to toxins during pregnancy: they should be designed in a manner that enables increased understanding about the biological processes that occur as a response to toxic exposure, the resulting cellular events and the primary regulatory effect of transcription factors.