Description of functional locus scenarios. The five types of scenarios utilized in each population, where the green arrow indicates the disease susceptibility locus (or loci) and called LD blocks are outlined in black. A) One SNP in the middle of an LD block. B) One SNP in the center of a block of LD. C) Two SNPs in an epistatic interaction in separate LD blocks. D) Two interacting SNPs, one in a block of LD and one outside. E) Two interacting SNPs in the same block of LD.