Lack of KIR2DL4 gene in a fertile Caucasian woman.

Killer cell immunoglobulin-like receptor (KIR2DL4) gene is present in virtually all humans. It encodes a receptor present on uterine and decidual natural killer (NK) cells and some peripheral blood NK cells. Its only known ligand is human leukocyte antigen-G molecule expressed on extravillous trophoblasts invading the decidua. Therefore, KIR2DL4 has been regarded as a molecule important for successful pregnancy. However, a multiparous woman from Africa, lacking KIR2DL4 gene, was described suggesting that this gene is not absolutely required for successful human reproduction. Here, we describe a Polish woman who delivered a child and who is not only lacking KIR2DL4 gene, but also possessing a KIR genotype virtually identical to that of the African woman mentioned above. Their genotypes are compared with few other KIR2DL4-negative genotypes and haplotypes described so far.