Toward a road map for global -omics: a primer on -omic technologies.

As highlighted in a recent editorial in the Journal (Am J Epidemiol. 2014;180(2):127-128), the research area of "-omics" includes genomics, proteomics, metabolomics, and nascent fields of scientific inquiry such as epigenomics and exposomics. These fields can be collectively referred to as "global -omics." Increasing efforts have been made over the past 2 decades to identify and modify environmental risk factors among persons who are susceptible to disease because of their genotype and to integrate genetic information and other biological variables with information about individual-level risk factors and group-level or societal factors related to the broader residential, behavioral, or cultural context. In genome-wide association studies, only a small proportion of heritability is explained by genetic variants identified to date, which has prompted researchers in bioinformatics and biostatistics to take into account nonlinear relationships due to gene-environment or gene-gene interactions. The exposome, which is dynamic and variable, consists of all of the internal and external exposures an individual incurs over a lifetime. Both the epigenome and exposome change with age. The prenatal and perinatal periods are thought to be important times for epigenetic marking. Once the human epigenome has been fully mapped, identification of the effects of all deleterious environmental exposures according to duration of exposure and time period will be a complex undertaking, requiring collaborative epidemiologic studies.