The primary DNA sequence is generally fixed at conception, but epigenetic marks are dynamic and modifiable
2009 Study Abstracts
Epigenetic modification can mediate environmental influences on gene expression and can modulate the disease risk associated with genetic variation. Epigenetic analysis therefore holds substantial promise for identifying mechanisms through which genetic and environmental factors jointly contribute to disease risk. The spatial and temporal variance in epigenetic profile is of particular relevance for developmental epidemiology and the study of aging, including the variable age at onset for many common diseases. This review serves as a general introduction to the topic by describing epigenetic mechanisms, with a focus on DNA methylation; genetic and environmental factors that influence DNA methylation; epigenetic influences on development, aging, and disease; and current methodology for measuring epigenetic profile. Methodological considerations for epidemiologic studies that seek to include epigenetic analysis are also discussed.
EPIGENETICS AND DISEASE
Disruption of epigenetic profile is a feature of most cancers and is speculated to play a role in the etiology of other complex diseases, including asthma, allergy, obesity, type 2 diabetes, coronary heart disease, autism spectrum disorders, and bipolar disorder and schizophrenia. The potential to identify distinct epigenetic biomarkers associated with eating disorders has also been explored. Disruption of epigenetic profile is also implicated in some adverse health outcomes for subjects conceived by means of assisted reproductive technologies.
ENVIRONMENTAL FACTORS AND THE EPIGENOME
Endocrine disruptors are chemicals that interfere with the function of hormones by mimicking, blocking, or disrupting their synthesis, transport, or elimination. Hormones are chemical messengers that travel through the blood to target cells where they interact with receptors that, in turn, directly influence gene activity, usually via epigenetic mechanisms. Any endocrine disruption may therefore have epigenetic consequences. Diethylstilbestrol is a synthetic estrogen. Prenatal exposure to diethylstilbestrol has been shown to increase the risk of cervical and vaginal cancer and pregnancy-related problems in women and testicular abnormalities in men. Diethylstilbestrol exposure in animals decreases promoter DNA methylation in reproductive tissues and increases methylation (and hence decreases activity) of DNMT. Such exposure also decreases methylation of the cancer-causing oncogene c-fos and the estrogen-responsive gene lactoferrin in mice.
- Read and download the full study (free access) Prospects for Epigenetic Epidemiology, on the NCBI, PubMed, PMC3290967, 2009 Feb 15.
- Image credit NCBI PubMed PMC3290967/figure/fig3.