Linkage disequilibrium

In this hypothetical example, the A₁ and B₁ alleles are more often found on the same chromosome than would be anticipated by chance alone. The same is true for the A₂ and B₂ alleles. Consequently, there is a deficiency of A₁B₂ and A₂B₁ haplotypes. This discrepancy between the observed and expected haplotype frequencies is linkage disequilibrium. The label "10%" between A and B is the recombination fraction between the A and B loci.