A potentially more powerful approach to disentangle LD from truly independently associated effects is to leverage different ancestral groups in a process known as trans-ethnic fine mapping (Kichaev & Pasaniuc, 2015). Trans-ethnic fine mapping exploits the fact that different ancestral groups (e.g., East Asian versus Native American ancestry) have different LD patterns across the genome. It is well known, for example, that regions of LD in individuals of European ancestry are large relative to individuals of sub-Saharan African ancestry. If a locus identified through GWAS shows different LD patterns in individuals of different ancestries, then conducting an association analysis in both ancestries can narrow the locus, thus reducing the set of credible candidate causal variants. For this reason, electrophysiological studies of different ethnic groups, such as those carried out with Native and Mexican American communities in the US (Ehlers & Gizer, 2013; Ehlers & Phillips, 2007; Ehlers, Wills, Phillips, & Havstad, 2015; Norden-Krichmar et al., 2015), are especially valuable even if they are not expected to greatly increase power to detect novel associations, nor do they obviate the need for large samples (e.g., see Table 3).
