Understanding the interplay between genetic and environmental factors that shape phenotypes has represented, historically, a thought-provoking area for biomedical, medical, and social sciences.
While the biology of the genome has witnessed unprecedented advances in the past three decades, identifying and studying the impact of environmental factors on live organisms remains a challenging endeavor. To address this unmet need, a new concept was defined to include all the environmental exposures that act during an individual’s lifetime, starting with the prenatal period.
“The principle behind the concept of the exposome was to be able to characterize a person’s complete exposure history throughout life, and this includes factors shaped by environment, lifestyle, occupation, socio-economic, and demographic conditions in order to better understand the causes of the diseases they experience,” says Christopher P. Wild, Ph.D., director of the International Agency for Research on Cancer (IARC), and author of the landmark 2005 article that first introduced the concept of the exposome.
Exposome research capitalizes on technological advances that previously provided unprecedented opportunities to mine the human genome and compare genomic regions across individuals and populations. “At this time, we do not have an equivalent set of tools to capture an individual’s exposure history to environmental or lifestyle factors,” says Dr. Wild.
This gap promises to be at least partially addressed by applying genomics and other related technologies such as metabolomics to reveal details about exposures. A key development is in epigenetics, a field that assumes a central position in the study of the exposome.
In addition to the DNA damage model for carcinogenesis, recent years revealed that gene expression and function may also be modulated by mechanisms that do not involve mutagenesis, and several environmental and lifestyle factors were shown to act by these pathways, which became known as epigenetic pathways.
Of these, DNA methylation is at the most advanced stage of understanding. “With methods that can comprehensively measure the DNA methylation status, for example, it has now become possible to explore the correlation between a particular exposure, the underlying mechanism of action, and disease risk,” explains Dr. Wild.