Although reports have clearly demonstrated the value of integrating data across related studies and even across disciplines (22), most genome-wide association studies to date have focused on a specific disease or trait. The PhenX Toolkit is designed to aid investigators who are interested in expanding their study to include measures that are outside of their primary area of expertise. For example, an investigator who is planning a neurology study may choose PhenX measures in the Nutrition and Dietary Supplements, Cancer, and Respiratory domains in addition to PhenX Neurology measures. It is also worth noting that some conditions or diseases may be associated with the same phenotype, such as obesity with cardiovascular disease and diabetes. Perhaps even more important, expanding genomics-based studies to include phenotypes outside of the primary research interest is essential to understanding pleiotropic genetic effects (23). Thus, as investigators extend their studies to incorporate PhenX measures, new relations between seemingly unrelated disciplines are likely to be uncovered. Figure 3 illustrates the incorporation of PhenX measures into individual studies and the resulting ability to combine data from multiple studies.
