Studying the Elusive Environment in Large Scale toward Precision Medicine
Chirag J Patel, Harvard University
Greater than 50% of complex disease risk is attributed to differences in an individual’s environment. Air pollution, smoking, and diet are documented environmental factors in disease risk, yet these factors are but a fraction of the “exposome”, the totality of the exposure load occurring through a person’s lifetime1. In contrast to genome sciences, we lack analytics methods to comprehensively assess quantitative indicators of environmental exposure in population disease risk. Investigating one or a handful of exposures at a time has led to a highly fragmented literature of epidemiologic associations. Much of that literature is not reproducible and selective reporting may be a major reason for the lack of reproducibility. A new paradigm is required to discover environmental exposures in disease while mitigating possibilities of selective reporting.
To remedy this problem, one can assess multiple personal exposures simultaneously in terms of their association with a condition/disease of interest; the top findings can then be tentatively validated in independent datasets. The main advantages in this process include the ability to search the space of exposures and adjust for multiplicity systematically and report all the probed associations instead of just the most significant results. We have used the term “environment-wide association studies” (EWAS) to describe the approach of searching the human exposome for factors associated with disease risk. In this talk, I will describe concepts of exposome science and discuss implications of environmental exposures in the coming era of “precision medicine”.