Study On The Polymorphism Of KIR Genes And HLA Ligands Of Different Ethnic Groups In China

Objective:KIR(Killer cell Immuoglobulin-like receptors)AND HLA are two essential genes in the human immune system,which play critical roles in the immune response to infectious and non-infectious diseases.The distribution and frequency of KIR and HLA alleles in different regions and populations in China are different.So far there some data are available on KIR gene and HLA gene polymorphism in some Chinese ethnic groups,still more KIR and HLA genes polymorphism data of ethnic groups and regions are needed to further elucidate the characteristics of alleles distribution and ligan-receptor association.The present study has studied the Deang,Jingpo,Achang,Dai,Lahu,Naxi,Pumi and Yao ethnic populations in Yunnan province.Buyi and Shui ethnic populations in Guizhou province,Tajik and Xibe ethnic populations in Xinjiang province,and Daur ethnic population in Inner Mongolia province.KIR gene polymorphism analysis of 18 ethnic population including Oroqen,Dongxiang ethnic populations in Gansu province,Li ethnic population in Hainan province,Salar ethnic population in Qinghai province and Qiang ethnic population in Sichuan province.Furthermore,HLA gene polymorphisms and KIR-HLA ligan-receptor association were analyzed in 4 ethnic populations,Deang,Jingpo,Achang and Dai in Dehong,who live in the same region of Southwestern Yunnan.Methods:(1)A total of 1,029 human Lymphoblastoid cell lines of 18 Chinese ethnic groups were derived from the Chinese National Immortal Cell Bank(Institute of Medical Biology,Chinese Academy of Medical Sciences).The PCR-SSP method was used to classify the presence or absence of 16 KIR genes.(2)Using whole exome sequencing(WES)combined with HLAreporter.v103 bioinformatics analysis method to type HLA gene alleles.(3)Use SPSS 24 to perform a chi-square test on the significance of the frequency distribution.(4)Using PHYLIP 3.6 and MEGA7 to construct the KIR gene phylogenetic tree based on the common KIR gene frequencies of the 18 populations in this study and the 38 populations of 20 reported populations.(5)Using R 3.6.1 to perform principal component analysis on the frequency of 9 KIR genes shared by 38 groups in the 18 groups and 20 reported groups in this study.(6)Use R 3.6.1 to analyze the correlation between the KIR and HLA carrier frequencies shared by the 4 groups in this study and other 14 groups from 10 studies previously reported.Results:The results of KIR gene polymorphism analysis in 18 ethnic groups showed(1)a total of 123 KIR genotypes were detected in the 1029 samples from the 18 studied ethnic groups.Dongxiang ethnic group had the most detected genotypes(34 types),while the other 4 ethnic groups,Daur,Qiang,Salar and Xibe,had the least with only 6 genotypes.(2)Among 13 ethnic populations including Dongxiang,De'ang,Bouyei and etc,the frequency of haplotype A is higher than that of haplotype B,among which the frequency of haplotype A in Daur is 89%,haplotype B frequency is 11%.There was no statistical difference on the frequency of A haplotype and B haplotype among the five populations of Achang,Jingpo,Yao,Oroqen,and Tajik.Both A and B haplotype frequencies were about 50%in the populations.(3)Among the activating KIR genes,the gene frequencies of 2DS1,2DS2,2DS3,2DS4,and 2DS5 are different in different populations,while the frequency of 3DS1 gene in different populations is not statistically different.Among the inhibitory KIR genes,the gene frequencies of 2DL2,3DL1,2DL3,and 2DL5 are different in different populations,especially the 2DL2 gene.There was no statistical difference in the distribution of 2DL1,2DL3,2DL4,3DL2,3DL3,2DP1,and 3DP1 gene frequencies in different populations.And the gene frequency of activating KIR genes 2DS1,2DS2,2DS3,2DS5 and 3DS1 is much lower than that of inhibitory KIR genes(except 2DL2,2DL5).(4)Principal component analysis of the KIR gene frequencies in a total of 38 ethnic groups,18 ethnic groups in the present study together with the 20 ethnic groups previously reported,The correlation between KIR gene distribution and language family and geographic location is not observed.(5)the genetic distance and phylogenetic tree based on the KIR gene frequency in the 38 Chinese populations show that language and geographical distribution clusters are not observed on the evolutionary tree.The HLA diversity analysis of the Jingpo,De'ang,Achang and Dai populations in southwestern Yunnan found that:(1)A total of 25 HLA-A alleles,52 HLA-B alleles,and 24 HLA-B alleles were detected in the four ethnic groups.The HLA-A,HLA-B,and HLA-C alleles were detected in Jingpo ethnic group with 17,27,and 14 respectively;in Deang ethnic group with 16,28,and 18 respectively;in Achang ethnic group with 15,26,and 18 respectively,in Dai ethnic group with 15,32,and 14 respectively.(2)Through the statistical analysis,there are 6 HLA-A alleles,4 HLA-B alleles,4 HLA-C alleles(A*02:01,A*02:07,A*11:01,A*11:50,A*24:02,A*24:07,B*15:02,B*15:32,B*38:02,B*46:01,C*01:02,C*04:03,C*07:02,C*12:03)are statistically different in the four groups,but there is no statistical difference in the frequency distribution of the same epitope among the four ethnic groups(HLA-A-Bw4,HLA-B-Bw4,HLA-C1 and HLA-C2).In addition,the high-frequency alleles in the four populations are not the same,and the order is also different.(3)principal component analysis of the KIR and HLA carrier frequencies of a total of 14 ethnic groups,which including the 4 ethnic groups from southwestern Yunnan and the 10 ethnic groups previously reported,revealed a significant negative correlation between KIR 2DL1 and HLA-C2.Conclusions:(1)The present study has further enriched the genetic diversity data of KIR and HLA for Chinese ethnic populations.The results show that KIR and HLA genes polymorphisms are significant differences in different Chinese ethnic populations,and the diversity may have resulted from demographic factors such as ethnic origin and their genetic backgrounds(2))There are differences in the distribution of HLA alleles among the Jingpo,De'ang,Achang and Dai populations in southwestern Yunnan,thus there is no statistical difference in the distribution of HLA epitopes.The results indicate that the polymorphism of HLA alleles in southwestern Yunnan only affects the strength of HLA binding to KIR receptors,but does not affect the types of KIR receptors that HLA binds to.(3)In the population,there is a strong negative correlation between the presence of the inhibitory 2DL1 gene and its corresponding HLA ligand.This shows the co-evolution of KIR and HLA two complex genetic systems.