Many investigators are now looking at using controls from one study as cases in another study as a way of expanding the size of an investigation without the cost of genotyping additional individuals. However, it is only possible when the subjects come from studies whose primary interests are not associated with each other. This becomes complex because it requires well-characterized phenotypes for selection of cases and controls, yet many of the phenotypes are secondary measures collected by the contributing studies and thus may not be well-characterized. Such phenotypes also may represent only a snapshot of the individual's phenotype at one point in time and may not be correlated with the development of future disease or conditions. GENEVA currently has a WG looking specifically at this issue, and its investigation is still in progress.
