that sampled in the study that first observed the marker-trait association, using the exact strategy outlined in the next section. Once credible evidence for this association has been established, replication efforts in other populations should type not only the marker known to be associated in the original population, but other markers that “tag” common variation in a region surrounding the marker. For fine mapping, differences in LD patterns across populations—notably the lower levels of LD in African-ancestry populations—might lead to refined estimates of the position of causal variants. [24, 25]
