Copy number variation leads to considerable diversity for B but not A haplotypes of the human KIR genes encoding NK cell receptors

The fusion gene 2DL5/3DP1 is carried on four different KIR haplotypes. The precise chromosome breakage in 2DL5/3DP1 (3DP1*004) is shared by these four haplotypes, suggesting a common ancestry rather than independent formation of the fusion gene by NAHR between different haplotypes. Instead, the haplotype structures are consistent with recombination occurring with different haplotypes, i.e., motif interchange, at the recombination hotspots sited between 3DP1 and 2DL4, after the fusion gene was created. Constituent haplotype motifs based on gene content are boxed. (f) Frequency. The numbers in the parentheses refer to the haplotypes defined in Figure 1.