Diversity of Killer Cell Immunoglobulin-like Receptor Genes in the Bai Ethnic Minority of Yunnan, China

Killer cell immunoglobulin-like receptors (KIRs), expressed in both natural killer (NK) cells and a subset of T cells, represent a family of both inhibitory and activating receptors that can regulate NK and T cells upon interacting with human leucocyte antigen (HLA) class I molecules on target cells. The number and distribution of KIR genes vary between individuals and populations from different geographical regions and ethnic origins. In this study, we investigated KIR gene frequencies and genotype diversities of 13 KIR genes, 2 pseudogenes, expressed and non-expressed forms of KIR2DL5 and the two subtypes, full-length and deleted forms, of KIR2DS4 in 100 unrelated healthy individuals of the Bai population, living in the Dali Bai autonomous prefecture in the Yunnan province. All individuals were typed positive for the three framework loci KIR3DL3, 2DL4 and 3DL2, as well as for three non-framework genes KIR2DL1, 2DL3 and the pseudogene KIR2DP1. The gene frequencies of the other KIR genes ranged from 7%-95%. The results of tested linkage disequilibrium (LD) among KIR genes demonstrated that they display a wide range of LD. χ2 analysis among non-ubiquitous genes, using the KIR gene frequency data from our study population, as well as from previously published population data, was conducted and revealed significant differences in the KIR2DL1, 2DL2, 3DL1 and KIR2DS1 genes. The results of the present study can be valuable for enriching the Chinese ethnical gene information resources of the KIR gene pool, for anthropological studies, as well as for KIR-related disease research.