FIGURE 1.

Illustration of co‐skewness in the AD‐affected and unaffected subjects. The diagram shows the joint distributions of the compound genotypes for the SNPs rs2075650, rs12721046, and rs429358 as proportions. The left (blue) column shows proportions of the compound genotypes among Alzheimer's disease (AD) non‐cases, and the right (red) displays proportions among AD cases. Larger dot size indicates a larger proportion. Rows keep track of the number of rs429358 minor alleles coding the ε4 allele. Observe that the distribution for cases is considerably more clustered along the diagonal (0,0,0), (1,1,1), (2,2,2) than for non‐cases. This phenomenon visually confirms our result that the mutual term $G_1^{h,m}$ increases substantially from non‐cases to cases for this triple. Thus we can think of the mutual term as a direct generalization of linkage disequilibrium and view co‐skewness as a more subtle metric as it contains additional pairwise information