The National Institutes of Health has initiatives aimed at addressing challenges associated with genotypic research, many of which are also relevant to the study of cGxE. For example, in recognition of the fact that gene identification requires large numbers, but one of the challenges that is often encountered as researchers attempt to pool their samples is the use of different measures across studies, the PhenX initiative was launched (www.phenX.org) (Hamilton et al., 2011). PhenX brought together panels of experts across a variety of research areas to come up with recommended consensus measures (including both outcome and environmental measures) for inclusion in genetics studies to encourage the use of common measures to facilitate cross-study comparisons and analyses. There are limitations to this approach: brief, low burden measures were preferentially selected to encourage more widespread uptake, which may result in less precise or comprehensive assessments in the case of some constructs. However, it represents a step toward facilitating collaborative efforts in genetics research. The use of standardized measures across studies could also help advance the cGxE field, with greater emphasis placed on
