We treated each GWA analysis and its replication efforts as one study, as in the original Science publications. Therefore, three studies were analyzed for between-study heterogeneity and meta-analysis was performed with random effects on these 3 estimates, as described above. In a sensitivity analysis, for each GWA investigation, we treated the GWA discovery data as a separate study from the GWA replication data. Thus in the sensitivity analysis, between-study heterogeneity was estimated and random effects meta-analysis was performed considering a maximum 6 estimates. Some markers had not been pursued for testing in the replication phase of all 3 GWA investigations, thus they are represented by 5 or 4 estimates in the sensitivity meta-analysis. We should caution that even with this further split, each of the estimates may still be composed on several sub-studies. For example, the replication efforts may be comprised on many smaller teams and their data have already been synthesized (again using fixed effects assumptions), but separate data for these sub-studies are not consistently available. In some cases, the pieces would be even impossible to separate, as for
