Combined Models of epistasis
genotypes* 1.1 1.2 2.1 2.2 3.1 3.2 4 5 6 7 8
AA/BB 0 0 0 0 0 0 0 0 0 0 0
AA/Bb 1 2 0 0 0 0 1 0 1 0 1
AA/bb 1 2 1 2 0 0 1 1 1 1 2
Aa/BB 2 1 0 0 0 0 1 0 1 0 1
Aa/Bb 2 2 0 0 0 0 1 0 2 0 2
Aa/bb 2 2 1 2 1 0 1 1 2 1 3
aa/BB 2 1 2 1 0 0 1 1 1 1 2
aa/Bb 2 2 2 1 0 1 1 1 2 1 3
aa/bb 2 2 2 2 1 1 1 1 2 2 4
*A, B: wild type alleles at loci A and B, respectively; a, b: variant alleles at loci A and B, respectively; 1: Dominant epistasis; 2: Recessive epistasis; 3: Dominant and recessive epistasis; 4: Double dominant epistasis without cumulative effect; 5: Double recessive epistasis without cumulative effects; 6: Double dominant epistasis with cumulative effect; 7: Double recessive epistasis with cumulative effects; 8: Quantitative; Of these, only the quantitative model is actually quantitative (the numbers in the other models represent categories). Models that have two versions (e.g., 1.1 and 1.2) are the cases where which SNP corresponds to the “A” hypothetical locus and which corresponds to the “B” hypothetical locus is not redundant.
Table 3: Coding system for eight different epistatic models for two-SNP interactions.