KIR and HLA Haplotype Analysis in a Family Lacking the KIR 2DL1-2DP1 Genes

Abstract

The killer cell immunoglobulin-like receptor (KIR) gene cluster exhibits extensive allelic and haplotypic diversity that is observed as presence/absence of genes, resulting in expansion and contraction of KIR haplotypes and by allelic variation of individual KIR genes. We report a case of KIR pseudogene 2DP1 and 2DL1 gene absence in members of one family with the children suffering from acute myelogenous leukemia (AML). Killer cell immunoglo-bulin-like receptor low resolution genotyping was performed by the polymerase chain reaction (PCR)-sequencespecific primers (SSP)/sequence-specific oligonucleotide (SSO) method and haplotype assignment was done by gene content analysis. Both parents and the maternal grandfather, shared the same Cen-B2 KIR haplotype, containing KIR 3DL3,-2DS2,-2DL2 and-3DP1 genes. The second haplotype in the KIR genotype of the mother and grandfather was Tel-A1 with KIR 2DL4 (normal and deleted variant),-3DL1,-22 bp deletion variant of the 2DS4 gene and-3DL2, while the second haplotype in the KIR genotype of the father was Tel-B1 with 2DL4 (normal variant),-3DS1,-2DL5,-2DS5,-2DS1 and 3DL2 genes. Haplotype analysis in all three offsprings revealed that the children inherited the Cen-B2 haplotype with the same gene content but two of the children inherited a deleted variant of the 2DL4 gene, while the third child inherited a normal one. The second haplotype of all three offspring contained KIR 2DL4,-2DL5,-2DS1,-2DS4 (del 22bp variant),-2DS5,-3DL1 and-3DL2 genes, which was the basis of the assumption that there is a hybrid haplotype and that the present 3DL1 gene is a variant of the 3DS1 gene. Due to consanguinity among the ancestors, the results of KIR segregation analysis showed the existence of a very rare KIR genotype in the offspring. The family who is the subject of this case is even more interesting because the father was 10/10 human leukocyte antigen (HLA)-matched to his daughter, all members of the family have the "best" donor KIR-B content and the presence of a rare KIR genotype with KIR 2DP1-2DL1 genes absence.