隐匿性HBV感染无偿献血人群KIR基因多态性的特征分析

Features of KIR gene polymorphisms in unpaid blood donors with occult hepatitis B infection

目的探讨无偿献血人群中隐匿性乙型肝炎病毒感染(OBI)献血者的KIR基因多态性及其特征分析。方法筛选2016年6月-2019年6月重庆市血液中心无偿献血人群中OBI献血者105例,采集外周血样提取DNA并作KIR基因分型;通过与国际等位基因网站公布的KIR基因型数据库对照分析,判断KIR基因型ID及单体型,计算基因表型频率(某种基因出现例数/总例数)、基因型频率(某中基因型出现例数/总例数)和基因频率(F)=√1-基因表型频率)。计数资料组间比较采用χ^2检验。结果105例OBI献血者均含有的KIR基因有2DL4、3DL2、3DL3和假基因3DP1;F>70%的KIR基因有2DL1、2DL3、3DL1、2DS4和假基因2DP1,其中KIR 2DS4第5外显子存在缺失的F为26.32%。F<30%的基因有2DL2、2DL5、2DS1、2DS2、2DS3、2DS5、3DS1。OBI献血人群分别与重庆汉族、河北汉族、江苏汉族和拉萨藏族比较,KIR 2DL3基因频率均降低(χ^2分别为9.598、12.236、13.719、10.974,P值均<0.05);OBI献血人群2DL2、2DL5、2DS2、2DS3与乌市维族比较差异均有统计学意义(χ2值分别为16.215、6.981、19.498、11.819,P值均<0.05);OBI献血人群2DL2、2DS1、2DS2、2DS3、2DS4与高加索人比较差异均有统计学意义(χ^2分别为22.477、3.877、34.937、6.909、4.271,P值均<0.05);OBI献血人群与重庆汉族相比,KIR 2DS4*del频率升高(χ^2=12.911,P<0.05)。OBI献血人群与长期慢性HBV感染组相比,2DS2、2DS3频率降低(χ^2分别为13.005、8.289,P值均<0.05),但2DS4、3DL1频率升高(χ^2分别10.032、3.865,P值均<0.05);OBI献血人群与强直性脊柱炎组相比,2DL3、2DS3基因频率降低(χ^2分别为7.851、16.504,P值均<0.05);OBI献血人群与男男同性恋HIV-AIDS组相比,2DS4、3DL1基因频率升高(χ^2分别为15.491、4.475,P<0.05);OBI献血人群与散发性急性戊型肝炎组相比,2DL1、2DL2、2DL3、2DL4、2DL5、2DS4、3DL2、3DL3、2DP1差异均有统计学意义(χ2分别为4.448、30.934、17.942、15.638、4.227、13.802、32.667、35.653、36.566,P值均<0.05)。共发现21种KIR基因型,其中基因型AA1(49.52%)最为常见,其次为BX2(18.1%)。结论OBI献血人群的KIR基因多态性具有自身特征,KIR 2DL3是OBI的潜在保护基因,KIR 2DS4*del则是OBI的潜在易感基因。

Objective To investigate the KIR gene polymorphisms and their features in unpaid blood donors with occult hepatitis B infection(OBI).Methods A total of 105 unpaid blood donors with OBI were screened out from the unpaid blood donors in Chongqing Blood Center from 2016 to 2019.Peripheral blood samples were collected for DNA extraction and KIR genotyping.KIR genotype ID and haplotype were determined based on a comparative analysis of the KIR genotype database published on the international allele website.Genotype frequency was calculated according to the equation of genotype frequency(F)=√1-f,in which f represented the proportion of a phenotype of KIR gene.The chi-square test was used for comparison of categorical data between groups.Results All 105 OBI blood donors had the KIR genes 2 DL4,3 DL2,3 DL3,and pseudogene 3 DP1.The KIR genes 2 DL1,2 DL3,3 DL1,2 DS4,and pseudogene 2 DP1 had an F value of>70%,among which the KIR gene 2 DS4 with exon 5 deletion had an F value of 26.32%.The KIR genes with low frequency(<30%)were 2 DL2,2 DL5,2 DS1,2 DS2,2 DS3,2 DS5,and 3 DS1.Compared with the Han population in Chongqing,Hebei,and Jiangsu and the Tibetan population in Lasa,the OBI blood donors had a significantly lower frequency of the KIR 2 DL3 gene(χ^2=9.598,12.236,13.719,and 10.974,all P<0.05).There were significant differences in the frequencies of 2 DL2,2 DL5,2 DS2,and 2 DS3 between the OBI blood donors and the Uyghur population in Urumqi(χ^2=16.215,6.981,19.498,and 11.819,all P<0.05).There were significant differences in the frequencies of 2 DL2,2 DS1,2 DS2,2 DS3,and 2 DS4 between the OBI blood donors and the Caucasians(χ^2=22.477,3.877,34.937,6.909,and 4.271,all P<0.05).Compared with the Han population in Chongqing,the OBI blood donors had a significant increase in the frequency of KIR 2 DS4*del(χ^2=12.911,P<0.05).Compared with the population with chronic HBV infection,the OBIblood donors had significant reductions in the frequencies of 2 DS2 and 2 DS3(χ^2=13.005 and 8.289,P<0.05)and significant increases in the frequencies of 2 DS4 and 3 DL1(χ^2=10.032 and 3.865,P<0.05).Compared with the population with ankylosing spondylitis,the OBI blood donors had significant reductions in the frequencies of 2 DL3 and 2 DS3(χ^2=7.851 and 16.504,P<0.05).Compared with the gays with HIV-AIDS,the OBI blood donors had significant increases in the frequencies of 2 DS4 and 3 DL1(χ^2=15.491 and 4.475,P<0.05).There were significant differences in the frequencies of 2 DL1,2 DL2,2 DL3,2 DL4,2 DL5,2 DS4,3 DL2,3 DL3,and 2 DP1 between the OBI blood donors and the population with sporadic acute hepatitis E(χ^2=4.448,30.934,17.942,15.638,4.227,13.802,32.667,35.653,and 36.566,P<0.05).A total of 21 KIR genotypes were found,among which genotype AA1 had the highest frequency of 49.52%,followed by genotype Bx2(18.1%).Conclusion OBI blood donors have unique features of KIR gene polymorphisms.KIR2 DL3 is a potential protective gene for OBI,while KIR 2 DS4*del is a potential susceptibility gene for OBI.