Figure 3. Schematic diagram of different linkage disequilibrium patterns in discovery and follow-up samples.

A) The associated tag SNP and a causal variant are in the same region of linkage disequilibrium in both the discovery and follow-up samples. Both the exact and local approaches may yield successful transfer. B) The associated tag SNP and a causal variant are not in the same region of linkage disequilibrium in both the discovery and follow-up samples. The exact approach will fail for the original tag SNP but the local approach may succeed for other proxy SNPs if they are in the same region of linkage disequilibrium as the causal variant in the follow-up sample.