Organization of the KIR gene cluster.

The KIR gene order is shown for the A haplotype and a representative B haplotype. Inhibitory KIR genes are shown as red boxes, whereas the activating genes are shown in green. The framework genes are indicated by grey boxes, and pseudogenes are indicated by black boxes. Each gene spans between 10–16 kb, and the intergenic distances are approximately 2 kb with the exception of the 14 kb region upstream of the KIR2DL4 gene.