When should G × E interactions be investigated?
The analysis of G × E interactions in genetic epidemiology can be done at both different time points during the research process and with varying scopes. The relevant research questions that could be addressed by a G × E interaction study include the identification of new disease genes, the characterization of gene effects, the clinical relevance of a G × E interaction and the public health impact of it.In the phase of identification of genetic risk factors, accounting for a G × E interaction might increase the power to detect genes with small marginal effects,23, 24, 25 especially if the effect of a gene is only relevant in an etiological subgroup of patients, defined by a certain exposure. Here, the interaction is not of specific interest per se. Especially for high-throughput genotyping of polymorphisms in hundreds of candidate genes or genome-wide association studies with several hundred thousands of polymorphisms, the inclusion and testing of interactions greatly increase the numb
