There have only been a small number of GEWIS publications to date. These include examples for cancer risk, including a large study that replicated interactions between alcohol and single nucleotide polymorphisms (SNPs) in relation to esophageal squamous cell carcinoma [Wu, et al. 2012], and a relatively small, unreplicated, finding for obesity and colorectal cancer [Siegert, et al. 2013]. As well as findings in other complex diseases and outcomes [Cornelis, et al. 2012; Hamza, et al. 2011; Hancock, et al. 2012; Manning, et al. 2012]. Notably, in some of these cases inclusion of an environmental factor assisted in identifying novel genetic loci, even though there was not strong evidence for a GxE interaction. The findings to date suggest that the number of novel genetic loci identified by a GEWIS discovery approach may be small, and the interaction effects modest. Therefore, it is important to have large studies incorporating accurate assessment of environmental exposures in well characterized populations and/or combined analysis of new or existing studies with harmonized environmental data across studies. It will be important to develop and use powerful analytical methods, as described below.
