Killer-cell immunoglobulin-like receptor genes linkage disequilibrium analysis in population of Vojvodina

Killer Immunoglobulin-like Receptors (KIRs) form a group of regulatory molecules that modulate cytolytic activity of natural killer cells and T cells through interaction with specific human leukocyte antigen (HLA) molecules on target cells. KIRs are encoded by the family of 16 homologous genes that vary substantially between haplotypes and display sequence polymorphism with allelic variation that also contributes to diversity within the complex. The aim of the study is to estimate two locus linkage disequilibrium for 16 KIR loci. In this study, we report the evaluation of KIR gene content, allele, haplotype and genotype frequencies in 175 unrelated healthy individuals from Vojvodina who were KIR typed by polymerase chain reaction-sequence specific primers genotyping assay. The linkage disequilibrium (LD) was studied at the structural level (presence or absence of 16 KIR genes). Our results revealed that linkage disequilibrium is present between telomeric gene pairs KIR2DL1~KIR2DL4, KIR2DP1~KIR2DL4, KIR2DP1~KIR3DL1, KIR2DL1~KIR3DL2, KIR2DP1~KIR3DL2, KIR2DL4~KIR3DL1, KIR2DL4~KIR2DS4, KIR2DL4~KIR3DL2 where (r2=1), but positive association between KIR genes, with higher observed than expected haplotype frequencies were observed for KIR3DS1~KIR2DS1 and KIR2DL5~KIR2DS1 pair of genes (r2=0.646) and (r2=0.371), respectively. Thirty-eight different genotypes were identified, where 12% of the individuals have unique genotype, present in only one person. Our results will help to understand the genetic background of the Vojvodina population, in illustrating the population migration events in the northern part of Serbia, in explaining the extensive genetic admixture amongst the different ethnic groups of the region and also in KIR-related disease studies.