Searching across-cohort relatives in 54,092 GWAS samples via encrypted genotype regression.

Explicitly sharing individual level data in genomics studies has many merits comparing to sharing summary statistics, including more strict QCs, common statistical analyses, relative identification and improved statistical power in GWAS, but it is hampered by privacy or ethical constraints. In this study, we developed encG-reg, a regression approach that can detect relatives of various degrees based on encrypted genomic data, which is immune of ethical constraints. The encryption properties of encG-reg are based on the random matrix theory by masking the original genotypic matrix without sacrificing precision of individual-level genotype data. We established a connection between the dimension of a random matrix, which masked genotype matrices, and the required precision of a study for encrypted genotype data. encG-reg has false positive and false negative rates equivalent to sharing original individual level data, and is computationally efficient when searching relatives. We split the UK Biobank into their respective centers, and then encrypted the genotype data. We observed that the relatives estimated using encG-reg was equivalently accurate with the estimation by KING, which is a widely used software but requires original genotype data. In a more complex application, we launched a finely devised multi-center collaboration across 5 research institutes in China, covering 9 cohorts of 54,092 GWAS samples. encG-reg again identified true relatives existing across the cohorts with even different ethnic backgrounds and genotypic qualities. Our study clearly demonstrates that encrypted genomic data can be used for data sharing without loss of information or data sharing barrier.

Genetic basis of pregnancy-associated decreased platelet counts and gestational thrombocytopenia.

ABSTRACT: Platelet count reduction occurs throughout pregnancy, with 5% to 12% of pregnant women being diagnosed with gestational thrombocytopenia (GT), characterized by a more marked decrease in platelet count during pregnancy. However, the underlying biological mechanism behind these phenomena remains unclear. Here, we used sequencing data from noninvasive prenatal testing of 100 186 Chinese pregnant individuals and conducted, to our knowledge, the hitherto largest-scale genome-wide association studies on platelet counts during 5 periods of pregnancy (the first, second, and third trimesters, delivery, and the postpartum period) as well as 2 GT statuses (GT platelet count < 150 × 109/L and severe GT platelet count < 100 × 109/L). Our analysis revealed 138 genome-wide significant loci, explaining 10.4% to 12.1% of the observed variation. Interestingly, we identified previously unknown changes in genetic effects on platelet counts during pregnancy for variants present in PEAR1 and CBL, with PEAR1 variants specifically associated with a faster decline in platelet counts. Furthermore, we found that variants present in PEAR1 and TUBB1 increased susceptibility to GT and severe GT. Our study provides insight into the genetic basis of platelet counts and GT in pregnancy, highlighting the critical role of PEAR1 in decreasing platelet counts during pregnancy and the occurrence of GT. Those with pregnancies carrying specific variants associated with declining platelet counts may experience a more pronounced decrease, thereby elevating the risk of GT. These findings lay the groundwork for further investigation into the biological mechanisms and causal implications of GT.

Genome-wide association and Mendelian randomisation analysis among 30,699 Chinese pregnant women identifies novel genetic and molecular risk factors for gestational diabetes and glycaemic traits.

AIMS/HYPOTHESIS: Gestational diabetes mellitus (GDM) is the most common disorder in pregnancy; however, its underlying causes remain obscure. This study aimed to investigate the genetic and molecular risk factors contributing to GDM and glycaemic traits. METHODS: We collected non-invasive prenatal test (NIPT) sequencing data along with four glycaemic and 55 biochemical measurements from 30,699 pregnant women during a 2 year period at Shenzhen Baoan Women's and Children's Hospital in China. Genome-wide association studies (GWAS) were conducted between genotypes derived from NIPTs and GDM diagnosis, baseline glycaemic levels and glycaemic levels after glucose challenges. In total, 3317 women were diagnosed with GDM, while 19,565 served as control participants. The results were replicated using two independent cohorts. Additionally, we performed one-sample Mendelian randomisation to explore potential causal associations between the 55 biochemical measurements and risk of GDM and glycaemic levels. RESULTS: We identified four genetic loci significantly associated with GDM susceptibility. Among these, MTNR1B exhibited the highest significance (rs10830963-G, OR [95% CI] 1.57 [1.45, 1.70], p=4.42×10-29), although its effect on type 2 diabetes was modest. Furthermore, we found 31 genetic loci, including 14 novel loci, that were significantly associated with the four glycaemic traits. The replication rates of these associations with GDM, fasting plasma glucose levels and 0 h, 1 h and 2 h OGTT glucose levels were 4 out of 4, 6 out of 9, 10 out of 11, 5 out of 7 and 4 out of 4, respectively. Mendelian randomisation analysis suggested that a genetically regulated higher lymphocytes percentage and lower white blood cell count, neutrophil percentage and absolute neutrophil count were associated with elevated glucose levels and an increased risk of GDM. CONCLUSIONS/INTERPRETATION: Our findings provide new insights into the genetic basis of GDM and glycaemic traits during pregnancy in an East Asian population and highlight the potential role of inflammatory pathways in the aetiology of GDM and variations in glycaemic levels. DATA AVAILABILITY: Summary statistics for GDM; fasting plasma glucose; 0 h, 1 h and 2h OGTT; and the 55 biomarkers are available in the GWAS Atlas (study accession no.: GVP000001, https://ngdc.cncb.ac.cn/gwas/browse/GVP000001) .

[Establishment of a PCR-SSP method for the simultaneous amplification and identification of the presence of KIR genes].

OBJECTIVE: To develop a polymerase chain reaction-sequence specific primer (PCR-SSP) method for simultaneous amplification and identification of the KIR genes among Chinese population. METHODS: Peripheral blood samples from 132 healthy donors who had given blood at Shenzhen Blood Center from January 2015 to November 2015 were selected as the study subjects. Based on the polymorphism and single nucleotide polymorphism (SNP) information of high-resolution KIR alleles in the Chinese population and the IPD-KIR database, specific primers were designed to amplify all the 16 KIR genes and the 2DS4-Normal and 2DS4-Deleted subtypes. The specificity of each pair of PCR primers was verified by using samples with known KIR genotypes. During PCR amplification of the KIR gene, co-amplification the fragment of human growth hormone (HGH) gene by multiplex PCR was used as the internal control to prevent false negative results. A total of 132 samples with known KIR genotypes were randomly selected for blind inspection to verify the reliability of the developed method. RESULTS: The designed primers can specifically amplify the corresponding KIR genes, with clear and bright bands for the internal control and KIR genes. The results of detection are fully consistent with the known results. CONCLUSION: The KIR PCR-SSP method established in this study can yield accurate results for the identification of the presence of KIR genes.

Adaptive Admixture of HLA Class I Allotypes Enhanced Genetically Determined Strength of Natural Killer Cells in East Asians.

Human natural killer (NK) cells are essential for controlling infection, cancer, and fetal development. NK cell functions are modulated by interactions between polymorphic inhibitory killer cell immunoglobulin-like receptors (KIR) and polymorphic HLA-A, -B, and -C ligands expressed on tissue cells. All HLA-C alleles encode a KIR ligand and contribute to reproduction and immunity. In contrast, only some HLA-A and -B alleles encode KIR ligands and they focus on immunity. By high-resolution analysis of KIR and HLA-A, -B, and -C genes, we show that the Chinese Southern Han (CHS) are significantly enriched for interactions between inhibitory KIR and HLA-A and -B. This enrichment has had substantial input through population admixture with neighboring populations, who contributed HLA class I haplotypes expressing the KIR ligands B*46:01 and B*58:01, which subsequently rose to high frequency by natural selection. Consequently, over 80% of Southern Han HLA haplotypes encode more than one KIR ligand. Complementing the high number of KIR ligands, the CHS KIR locus combines a high frequency of genes expressing potent inhibitory KIR, with a low frequency of those expressing activating KIR. The Southern Han centromeric KIR region encodes strong, conserved, inhibitory HLA-C-specific receptors, and the telomeric region provides a high number and diversity of inhibitory HLA-A and -B-specific receptors. In all these characteristics, the CHS represent other East Asians, whose NK cell repertoires are thus enhanced in quantity, diversity, and effector strength, likely augmenting resistance to endemic viral infections.

[Association of molecular genetic polymorphism of KIR-HLA systems with acute leukemia in Southern Chinese Han].

OBJECTIVE: To investigate the association of molecular genetic polymorphism of KIR-HLA systems with acute lymphoblastic leukemia (ALL) and acute myelocytic leukemia (AML) in southern Chinese Han. METHODS: A total number of 323 cases of adult ALL patients, 350 adult AML, and 745 random healthy controls were tested by KIR PCR-SSP and HLA-A, -B, -C sequence-based typing (PCR-SBT) methods. The molecular genetic polymorphisms of KIR genes and KIR gene profiles, classⅠ HLA ligands, and KIR receptor +HLA ligand combinations were compared between patient and healthy control groups. RESULTS: A total number of 32 and 33 different kinds of KIR profiles were identified in the ALL and AML patient groups. Compared with the observed frequencies of KIR profiles in healthy controls, the observed frequencies of KIR profile AA1 were significantly lower in both the ALL and AML groups (ALL group: 45.79% vs. 55.30%, Pc=0.004; AML group: 48.27% vs. 55.30%, Pc=0.030). In the ALL group, the observed frequencies of 2DL2 gene and 2DL2+HLA-C1 combination, 2DS2 gene and 2DS2+HLA-C1 combination were significantly higher than those in healthy controls (P<0.05), whereas the frequencies of 2DL3 gene, HLA-A3/A11 ligand and 3DL2+HLA-A3/A11 combination were significantly lower than those in healthy controls. However, no significant differences remained after Bonferroni correction (Pc>0.05). In AML group, the observed frequencies of both 2DS1 and 2DL5 genes were significantly higher than that in healthy controls, whereas the frequencies of HLA-C2 ligand and 2DL1+HLA-C2 combination were significantly lower than that in healthy controls(P<0.05). However, no significant difference existed after Bonferroni correction (Pc>0.05). CONCLUSION: This study revealed some potential susceptibility or protective factors related to acute leukemia in southern Chinese Han, especially the protective factor KIR profile AA1, which might provide new clues and theoretical basis for the pathogenesis of acute leukemia and individualized immunotherapy.

Microarray-based analysis of whole-genome DNA methylation profiling in early detection of breast cancer.

Emerging evidence indicated that changes in DNA methylation early in breast cancer (BC) development might be clinically relevant for therapeutic decisions. Through analysis of whole-genome gene expression microarray and DNA methylation microarray, we explored genes with abnormal DNA methylation in BC for early detection. Firstly, human BC tissues and adjacent non-cancerous tissues were collected from nine BC patients. Gene expression microarray sequencing was conducted for identifying differentially expressed genes and DNA methylation microarray sequencing for differentially methylated genes in BC. Differentially expressed genes and methylated genes in BC were further explored using the Cancer Genome Atlas database. The correlation between DNA methylation and gene expression was illustrated by multiple comparisons. In other 60 clinical samples, methylation specific polymerase chain reaction (PCR) and reverse transcription quantitative PCR were applied for the methylation of HOXA4 and IGF1 genes in BC and adjacent non-cancerous tissues. In total, 1680 upregulated genes and 1249 downregulated genes were determined in BC. Chromosome 16 and 17 showed more differentially methylated genes, and DNA methylation level was increased in BC tissues in each gene region. Chromosome 19 showed more differentially methylated genes, and DNA methylation level was increased in BC tissues in the exoniensis 1, untranslated region-5 and transcriptional start site 200 gene regions. In other 60 clinical samples, HOXA4 and IGF1 in BC tissues presented increased DNA methylation and decreased gene expression in BC. MCF7 cells treated with RG108 showed decreased HOXA4 and IGF1 expressions. It was estimated that HOXA4 and IGF1 were identified with increased DNA methylation and decreased gene expression in BC, which may serve as biomarkers in early BC detection.

[A protective effect conferred by KIR3DL1 and its cognate ligand against cervical cancer among ethnic Han Chinese population and its potential mechanism].

OBJECTIVE: To explore the role of inhibitory KIR (iKIR) and its cognate HLA ligand in the occurrence and development of cervical cancer among ethnic Han Chinese and its potential mechanism. METHODS: Peripheral blood samples from 265 Han Chinese patients with cervical intraepithelial neoplasia (CIN)/cervical cancer and 200 ethnically matched healthy controls were collected. The results of KIR PCR-SSP, HLA PCR-rSSO and KIR3DL1 PCR-SBT, together with cervical cancer data from the TCGA database, were used to assess the association of iKIR genes, receptor-ligand gene combinations, iKIR transcription level in the tumor tissue and the KIR3DL1 alleles with the occurrence and development of cervical cancer. RESULTS: Among the four iKIR genes (KIR2DL1, 2DL2/3, 3DL1 and 3DL2), the frequencies of KIR3DL1 and KIR3DL1-HLA-Bw4 genes among controls were significantly higher than those of the cervical cancer group (96.5% vs. 87.0%, P = 0.018; 81.5% vs. 64.8%, P=0.009). The survival rate of cervical cancer patients with a high transcription level of KIR3DL1 in tumor tissues was significantly higher than those with a low/medium transcription level (P=0.028). The frequency of strong-inhibitory and high-expression KIR3DL1*01502 allele among the healthy population was significantly higher than that of the cervical cancer group (76.0% vs. 59.3%, P =0.015). CONCLUSION: Combined KIR3DL1 and KIR3DL1-HLA-Bw4 can confer a protective effect against the development of cervical cancer, which may be attributed to the strong-inhibitory and high-expression allele of KIR3DL1*01502.

[Association of genetic polymorphisms of KIR-HLA system with chronic myeloid leukemia among ethnic Hans from southern China].

OBJECTIVE: To explore the association of KIR-HLA gene polymorphism with chronic myeloid leukemia (CML) among ethnic Hans from southern China. METHODS: A total of 172 adult CML patients and 480 unrelated healthy controls were screened for the presence of KIR with sequence-specific primers-PCR (PCR-SSP) and sequence-based typing (SBT) of HLA-A, -B and -C loci. Polymorphisms of the KIR-HLA system were analyzed at 4 levels, and the frequencies of KIR framework genes and KIR profiles, classⅠHLA ligands, matched KIR+HLA pairs and KIR-HLA compound profile were compared between the two groups. P values were calculated using SPSS 13.0 software. RESULTS: For the CML group, the frequencies of HLA-C2 ligand, 2DL1+HLA-C2 pair and HLA-B Bw4-80I were significantly lower than those of the control group, suggesting a protective effect against CML (HLA-C2: OR=0.386, 95%CI:0.240-0.620, P<0.01; 2DL1+HLA-C2: OR=0.316, 95%CI:0.191-0.525, P<0.01; HLA-B Bw4-80I: OR=0.576, 95%CI:0.384-0.862, P<0.01). The frequencies of KIR2DL1 ligand (HLA-C2) and KIR3DL1 ligand (HLA-B Bw4-80I) in the CML group were significantly lower than that of the control group, suggesting that the HLA-C2 and HLA-B Bw4-80I expression is probably decreased in the CML patient group, which led to reduced inhibitory signal and enhanced activating signal of KIR2DL1+ and/or KIR3DL1+ NK cells. Notably, the frequency of KIR-HLA compound profiles ID2 (KIR AA1-HLA-C1/C1-Bw6/Bw6-A3/11) in CML patients significantly increased in the CML patient group compared with the control group, suggesting that the KIR-HLA compound profiles ID2 may be a risk factor for CML (OR=2.163, 95%CI 1.198-3.906, P<0.01). CONCLUSION: Above analysis has identified certain protective and risk factors for CML from the KIR-HLA system, which may provide a clue for the pathogenesis of leukemia and development of individualized immune therapy.

[Genetic polymorphisms of KIR2DS4 gene among ethnic Hans from southern China].

OBJECTIVE: To study genetic polymorphisms of the KIR2DS4 gene among ethnic Hans from southern China. METHODS: Genomic DNA was isolated from 306 unrelated individuals and amplified with KIR2DS4-specific PCR primers. KIR2DS4-positive samples were genotyped for the entire coding sequence by sequencing-based typing (SBT). Assignment of allelic genotypes was accomplished by using Assign 3.5 software. For samples with inconclusive SBT results, RT-PCR products covering the entire coding sequence of the KIR2DS4 gene were subjected to cloning and haplotype sequencing. RESULTS: Among all tested samples, 297 were demonstrated to have carried the KIR2DS4 framework gene. For KIR2DS4-positive samples subjected to SBT for the entire coding sequences, no background was observed with the obtained sequences. Three of the seven identified alleles were of novel types, which were officially named by the KIR subcommittee of the World Health Organization Nomenclature Committee for Factors of HLA System. The observed frequencies for the 7 alleles were KIR2DS4*00101 (78.8%), *003 (10.5%), *004 (16.0%), *010 (23.2%), *017 (0.3%), *00105 (0.3%) and *018 (0.7%), respectively. Allele KIR2DS4*007 was not found. The overall frequency for normal cell-surface expression KIR2DS4 alleles including 2DS4*00101, *017 and *00105 was 79.4%, and that for non cell-surface expression alleles including 2DS4*003, *004, *010 and *018 was 50.4%. The ratio between the two was 1.6:1. CONCLUSION: The present study has elucidated the allelic diversity of KIR2DS4 among ethnic Hans from southern China, which may provide valuable data for transplantation as well as studies on KIR-associated disease and evolution.

[Study of polymorphisms of HLA class â (-A, -B, -C) and class â ¡ (DRB1, DQA1, DQB1, DPA1, DPB1) genes among ethnic Hans from Southern China].

OBJECTIVE: To study the genetic polymorphisms of human leukocyte antigen (HLA)- A, B, C, DRB1, DQA1, DQB1, DPA1and DPB1among ethnic Hans from southern China. METHODS: 481 randomly selected individuals were genotyped using a polymerase chain reaction (PCR) sequence-based typing (SBT) method for the above genes. Their allele frequencies were determined by direct counting. RESULTS: In total, 28 HLA-A, 57 HLA-B, 28 HLA-C, 40 HLA-DRB1, 18 HLA-DQA1, 17 HLA-DQB1, 6 HLA-DPA1and 21 HLA-DPB1alleles were identified. Among these, common alleles (with allelic frequencies > 0.05) included A*1101, A*2402, A*0207, A*3303, A*0201, B*40:01, B*46:01, B*58:01, B*13:01, B*15:02, C*01:02, C*07:02, C*03:04, C*03:02, C*08:01, C*03:03, C*04:01, DRB1*09:01, DRB1*15:01, DRB1*12:02, DRB1*08:03, DRB1*03:01, DRB1*04:05, DRB1*11:01, DQA1*01:02, DQA1*03:02, DQA1*03:03, DQA1*06:01, DQA1*01:03, DQA1*05:05, DQA1*01:04, DQA1*03:01, DQA1*05:01, DQB1*03:01, DQB1*03:03, DQB1*06:01, DQB1*05:02, DQB1*03:02, DQB1*02:01, DQB1*03:02, DQB1*06:02, DPA1*02:02, DPA1*01:03, DPA1*02:01, DPB1*05:01, DPB1*02:01, DPB1*13:01, DPB1*04:01and DPB1*02:02.For each of the locus, the overall frequencies of common alleles were 75.57%, 52.81%, 78.28%, 62.16%, 86.70%, 77.23%, 95.32% and 81.59%, respectively. CONCLUSION: The allelic frequencies of the 8 selected HLA loci among ethnic Hans from southern China may served as a reference for anthropology, legal medicine, transplantation and disease association studies.

[Progress in research on genetic polymorphisms and sequence-based typing of KIR genes].

Killer cell immunoglobulin-like receptors (KIRs) are members of the immunoglobulin superfamily expressed on natural killer (NK) cells and a subset of T cells. Given the receptor-ligand relationship between certain KIR and human leukocyte antigen (HLA) classⅠmolecules, the KIRs are involved in the regulation of NK cell activation through conveying activating or inhibitory signals, which plays an important role in immunities involved in transplantation, tumor, infection as well as autoimmune diseases. This paper has provided a review for the research on KIR gene polymorphisms and summarized the characteristics of the sequence-based typing method for KIR genes.

[Cloning and sequencing of KIR2DL1 framework gene cDNA and identification of a novel allele].

OBJECTIVE: To develop an assay for cDNA cloning and haplotype sequencing of KIR2DL1 framework gene and determine the genotype of an ethnic Han from southern China. METHODS: Total RNA was isolated from peripheral blood sample, and complementary DNA (cDNA) transcript was synthesized by RT-PCR. The entire coding sequence of the KIR2DL1 framework gene was amplified with a pair of KIR2DL1-specific PCR primers. The PCR products with a length of approximately 1.2 kb were then subjected to cloning and haplotype sequencing. RESULTS: A specific target fragment of the KIR2DL1 framework gene was obtained. Following allele separation, a wild-type KIR2DL1*00302 allele and a novel variant allele, KIR2DL1*031, were identified. Sequence alignment with KIR2DL1 alleles from the IPD-KIR Database showed that the novel allele KIR2DL1*031 has differed from the closest allele KIR2DL1*00302 by a non-synonymous mutation at CDS nt 188A>G (codon 42 GAG>GGG) in exon 4, which has caused an amino acid change Glu42Gly. The sequence of the novel allele KIR2DL1*031 was submitted to GenBank under the accession number KP025960 and to the IPD-KIR Database under the submission number IWS40001982. A name KIR2DL1*031 has been officially assigned by the World Health Organization (WHO) Nomenclature Committee. CONCLUSION: An assay for cDNA cloning and haplotype sequencing of KIR2DL1 has been established, which has a broad applications in KIR studies at allelic level.

[Sequence analysis of a novel allele HLA-C*01:78].

OBJECTIVE: To investigate the genetic basis for a novel allele HLA-C*01:78. METHODS: Genomic DNA was extracted from peripheral blood using a QIAGEN quick DNA extraction kit. The regions encompassing HLA-C from exon 1 to intron 3 and intron 3 to 3'UTR were amplified and cloned using a cloning sequencing kit in order to split the two alleles apart. Selected clones were sequenced to include exons 2 to 4. RESULTS: Sequencing results have indicated the HLA-C alleles of the proband to be a novel C*03:04 allele. The sequence has been submitted to GenBank (KF049216). BLAST analysis has confirmed the novel allele to have one nucleotide difference as C*01:03 at genomic nt316C>A (codon 82CGC>AGC) in exon 2, which has resulted in replacement of one amino acid (82R>S). CONCLUSION: The novel allele has been officially named as C*01:78 by the WHO Nomenclature Committee. The HLA allele type of the proband was therefore A*02:07, 24:02; B*40:01, 46:01; C*01:78, 03:04; DQB1*05:02, 05:02; DRB1*16:02, 16:02.

Discovery of the novel KIR2DL3*00111 allele in a Chinese Han individual.

The novel KIR2DL3*00111 allele differs from the closest allele KIR2DL3*00101 by a single silent mutation.

[A study of HLA-DPA1 and DPB1 matching status for unrelated donor-recipient pairs matched at allele level for HLA-A, -B, -C, -DRB1 and -DQB1 loci].

OBJECTIVE: To analyze the status of HLA-DPA1 and DPB1 matching for unrelated donor-recipient pairs matched at high-resolution allele level for HLA-A, B, C, DRB1 and DQB1 loci. METHODS: A total of 76 unrelated donor-recipient pairs matching at allele level for HLA-A, B, C, DRB1 and DQB1 loci were subjected to HLA-DPA1 and DPB1 sequence-based typing (SBT). HLA-DPA1and DPB1 matching status at high-resolution allelic level was also analyzed. RESULTS: The allelic identity ratio for single HLA-DPA1 and DPB1 were 17.1% and 9.2%, respectively. HLA-DPA1 and DPB1 allelic identity ratio were both very low. The majority of unrelated donor-recipient pairs (73.7%) had an incompatibility at 1 HLA-DPA1 allele, 9.2% of pairs had an incompatibility at 2 DPA1 alleles. As for the high-polymorphic HLA-DPB1 gene, 57.9% of studied donor-recipient pairs had an incompatibility at 1 HLA-DPB1 allele, almost 1/3 (32.9%) of them were completely incompatible. When HLA-DPA1 and DPB1 genes were analyzed together, the donor-recipient pairs matched at 2/4 was the most common (51.4%), 4/4 allelic complete matched pairs accounted for 5.6%, and 0/4 matched pairs accounted for 8.3%. CONCLUSION: Our results indicated that the ratio of HLA-DPA1 and DPB1 complete match in the unrelated donor-recipient pairs matching at allelic level for HLA-A, B, C, DRB1 and DQB1 loci were very low. The effect of HLA-DPA1 and DPB1 matching status on clinical unrelated stem cell transplantation still needs to be elucidated.

Identification of the novel KIR3DL3*118 allele in a Chinese Han individual.

The novel KIR3DL3*118 allele differs from the closest allele KIR3DL3*01002 by a single missense mutation at CDS nt502 A > G in exon 4.

Identification of the novel KIR3DL1*00703 allele in a Chinese Han individual.

The novel KIR3DL1*00703 allele differs from the closest allele KIR3DL1*00701 by a single silent mutation.

Characterization of the novel KIR3DL1*01507 allele identified in a Chinese Han individual.

The novel KIR3DL1*01507 allele differs from the closest allele KIR3DL1*01502 by a single synonymous mutation.

Donor with HLA-C2 is associated with acute rejection following liver transplantation in Southern Chinese.

Apart from presenting peptides to T cells, class I HLA molecules serve as ligands for killer cell immunoglobulin-like receptor (KIRs) and regulate the response of natural killer (NK) cells. The role played by HLA and KIR in the acute rejection (AR) following liver transplantation has been controversial. In this retrospective study, we assessed the influence of class I HLA alleles, HLA matching between donor-recipient pairs, recipient KIR and donor HLA ligands on AR following liver transplantation in southern Chinese. In total, 143 recipients and 78 donors obtained from a single transplant center were included in the study cohort. Thirty-three recipients with histologically confirmed AR were observed. We found that the incidence of AR did not correlate with donor or recipient class I HLA alleles and HLA matching. Neither recipient KIR gene nor the KIR genotype was associated with AR, moreover, high-resolution genotyping of 14 functional KIR genes of recipients showed that no KIR allele was independently associated with AR. However, the frequency of HLA-C2+ donor significantly increased in AR group compared with NAR group (52.9% vs. 24.6%, p = 0.03). In the presence of HLA-C2 by the donor allograft, AR was more frequently observed in recipients with normal expressed KIR2DS4 (43.8% vs. 15.0%, p = 0.03). Donor with HLA-C2 is therefore a major determinant of AR, which can confer risk effect in liver transplantation. Our findings can provide valuable clues for better understanding pathogenesis of AR and have important clinical implications in liver transplantation for Chinese.