Fig. 3From: Leveraging local ancestry to detect gene-gene interactions in genome-wide dataTagging interaction effects in a multiple causal model. A latent variable Z is generated as a function of an increasing number of SNPs at a single locus, explaining altogether 50 % of its variance. The average value of Z across 20,000 replicates of 10,000 admixed samples is plotted for each three local ancestry classes. The effect of the SNPs is drawn from a normal (a) and left-truncated normal (b) distribution with a mean of 0 (upper panel). When the SNP effects are null on average, the average values of Z do not differ by local ancestry and ρ ZL , the correlation between Z and local ancestry, is also null on average. Conversely, when the average effect of the SNPs is not null, ρ ZL increases with an increasing number of causal variants (lower panel)Back to article page