Environmental epigenomics and disease susceptibility

this was the first Keystone symposium organized in the area of environ mental epigenetics. the meeting brought together a broad group of scientists research­ ing topics as diverse as epidemi ology, toxi­ cology, clinical medicine, mol ecular and cellular biology, and epigenetics. the meet­ ing was organized by randy Jirtle (Duke u., uSa), Moshe Szyf (Mcgill u., canada), and Frederick tyson (NiEHS, National institutes of Health, uSa) and had an almost equal distribution of graduate students, post­ doctoral fellows, new and established inves­ tigators. the size of the meeting and the diversity of its attendees was an indication that the field of environmental epi genetics is quickly becoming established. as the name suggests, environmental epigenomics seeks to understand the influ­ ence of the environment on the epigenome and the combined effect of these factors on human health. they are linked by epidemio­ logical and experimental data indicating that prenatal and early postnatal exposure to environmental factors result in permanent epigenetic modifications, which influence the likelihood of developing adult­onset diseases and neurodegenerative disorders. in the words of the organizing committee, the meeting sought to “provide evidence that environmental exposures during early development can alter the risk of develop­ ing medical conditions, such as asthma, autism, cancer, cardiovascular disease, dia­ betes, obesity, and schizophrenia later in life by modifying the epigenome.” the Keynote address was given by Eva Jablonka (tel aviv u., israel), who focused on the history of epigenetics, starting with the work of conrad Waddington. She emphasized the importance of epigenetic transgenerational inheritance by mention­ ing several examples of this phenomenon, and suggested that future research needs to incorporate epigenetics into the fields of population biology and evolution. an interesting discussion that followed this talk addressed the terminology and definitions associated with epigenetic inheritance, and suggested ways of qualifying different routes and levels of epigenetic transmission that might reduce confusion in scientific and public discourse on the topic. When DNa methylation was discovered (Singer et al, 1977), the term ‘epigenetic inheritance’ was used to describe the repli­ cation of the epigenome—DNa methyla­ tion—upon cell proliferation and mitosis (Singer et al, 1977). unfortunately, the defi­ nition of inheritance refers to generational transmission of information and not the mitotic stability of information. therefore, it was suggested by some that the stability and replication of the epigenome on cell proliferation and mitosis be referred to as ‘mitotic stability’, while the generational trans mission of epigenetic information be defined as ‘epigenetic inheritance’.