GWA studies and their meta-analyses have already resulted in an unprecedented number of genetic associations with strong statistical support [6]. At the same time, they have convincingly shown that effect sizes are almost always moderate or small and that with current platforms and sample sizes we are still unable to explain the large majority of genetic risk for most common diseases. We still don’t know whether what we have found with current resources is the tip of the iceberg or the bottom of the barrel [49]. This means that larger and larger studies and meta-analyses will probably continue to be performed in an effort to unearth more genetic risk variants of interest, if the resources can be met. The large majority of research to-date has been performed with case-control samples from pre-existing studies and in populations of Caucasian descent. There will be a challenge to extend the observations in new prospective cohorts and biobanks [50] and across populations with different ancestries. Moreover, incorporating environmental and lifestyle components into meta-analytic evaluations of large-scale evidence will also be a challenge.
