The current GWA strategy of using preselected markers to search for risk variants common in human populations is giving way to a paradigm of using whole-genome sequence approaches that can search for rare disease-risk variants as well. Future GWA studies —and some studies now in progress — will incorporate partial or complete genome sequences on some or all of the study participants. For many of the same reasons that GWA studies to date have emphasized populations of European descent, early sequence studies might also have a European focus. As we have seen, however, rare risk variants whose detection is a priority of sequence-based studies are likely to be more geographically restricted than the common variants currently of interest. Consequently, it will be even more important in sequence-based GWA studies than in current studies of common variants that multiple populations be considered.
