Gene–environment-wide association studies: emerging approaches

Despite the yield of genome-wide association studies, the variants identified explain little of the heritability of most complex diseases. This unexplained heritability could be partly due to gene–environment (G×E) interactions. This Review provides a guide to designs and analytical approaches for studying specific G×E interactions. Despite the yield of recent genome-wide association (GWA) studies, the identified variants explain only a small proportion of the heritability of most complex diseases. This unexplained heritability could be partly due to gene–environment (G×E) interactions or more complex pathways involving multiple genes and exposures. This Review provides a tutorial on the available epidemiological designs and statistical analysis approaches for studying specific G×E interactions and choosing the most appropriate methods. I discuss the approaches that are being developed for studying entire pathways and available techniques for mining interactions in GWA data. I also explore methods for marrying hypothesis-driven pathway-based approaches with 'agnostic' GWA studies.