HLA-B*44:138Q: Evidence for a confined deletion and recombination events in an otherwise unaffected HLA-haplotype

We discovered a new HLA-B allele, HLA-B*44:138Q, and confirmed its segregation. For characterisation, we used serology, sequence specific oligonucleotide (SSO), sequence specific primer (SSP), and full length sequencing by Sanger and next-generation sequencing. From an evolutionary point the 5' part of the new allele is identical with alleles from the HLA-B*44:02 group, while its 3' part is identical to the HLA-B*15:18:01:02 allele, the breakpoint being located somewhere between intron 3 and exon 4. The salient feature of the new allele is a deletion of codon 94 in exon 3, which is unique for HLA-alleles reported so far. Gene conversion can be hypothesised in the generation of this HLA sequence; however, the deletion seems to have occurred additionally. Other HLA-alleles of the new allele's haplotype were common alleles.

Characterization of a novel allelic variant in HLA-B*46:01 lineage, HLA-B*46:01:25, by cloning, phasing and sequencing

A new allelic variant in HLA-B*46:01 lineage, HLA-B*46:01:25, has been identified in a male individual of Mongol ethnicity residing in northern China. Following polymerase chain reaction-sequence-based typing (PCR-SBT), this novel variant was further confirmed by cloning, phasing and sequencing. HLA-B*46:01:25 differs from HLA-B*46:01:01 by a single synonymous T substitution at nucleotide position 137 (C - T) in exon 4, corresponding to codon 228 (ACC-ACT) of the mature HLA-B mRNA molecule.

Characterization of a novel allelic variant in HLA-B*40 lineage, HLA-B*40:298:02, by cloning and sequencing

A novel allelic variant in HLA-B*40 lineage, HLA-B*40:298:02, has been identified in an individual of Han ethnicity afflicted with nasopharyngeal carcinoma in Hunan province, southern China. Following polymerase chain reaction-Sanger sequence-based typing (PCR-SBT), this new variant was further confirmed by two distinct strategies of cloning and sequencing. HLA-B*40:298:02 differs from HLA-B*40:298:01 by a single synonymous cytosine substitution at nucleotide position 26 (T→C) in exon 3, which corresponds to codon 99 of the mature HLA-B mRNA molecule. This new allele has an estimated frequency of 0.0002, in about 2,500 sequence-based typed subjects from the same population.

Characterization of a novel HLA-B*39:01:01-related allele, HLA-B*39:130, by cloning and phasing

A novel HLA-B*39:01:01-related variant, HLA-B*39:130, has been identified in a normal individual of Han ethnicity in Hunan province, southern China. Following Sanger polymerase chain reaction-sequence-based typing (PCR-SBT), this new allele was further confirmed by cloning, phasing and sequencing. Aligned with HLA-B*39:01:01, HLA-B*39:130 has a nonsynonymous thymine substitution at nucleotide position 94 in exon 4, resulting in amino acid change from threonine to isoleucine at codon 214 (ACA→ATA) of the mature HLA-BmRNA molecule.

HLA-B allele dropout in PCR sequence-specific oligonucleotide probe typing due to intronic polymorphism in the novel B*58:01:01:02 allele

Currently, Luminex technology based on the PCR sequence-specific oligonucleotide (SSO) probe method has been widely used for HLA genotyping in the immunogenetics laboratories. Here, we reported a case with HLA-B allele dropout by Luminex technology. The initial HLA-B result of the Luminex method with a commercial agent kit was inconclusive, and then, the result of PCR-SBT technology indicated the dropout as a HLA-B*58 allele. Subsequently, the full-length sequence of HLA-B allele was determined by TOPO-TA cloning, and a novel allele B*58:01:01:02 was identified in the individual. Compared with HLA-B*58:01:01:01, the novel allele showed some nucleotides difference at 509 C>T, 521 T>G and CCC insertion in position 503 of intron 2. According to the full-length sequence, the new mutations of intron 2 were contributed to HLA-B locus allele dropout in the sample. Our results indicated multiplatform should be used to improve the HLA typing accuracy when a conclusive HLA genotype cannot be determined.

A novel allele, HLA-B*55:70 was identified in a Chinese cord blood donor

HLA-B*55:70 has one base substitution at position 199 C>T in exon 2 compared to HLA-B*55:02:01.

HLA-A, -B and -DRB1 allele and haplotype frequencies of 8333 Chinese Han from the Zhejiang province, China

The distribution of human leucocyte antigen (HLA) allele and haplotype is varied among different ethnic populations. In this study, HLA-A, -B and -DRB1 allele and haplotype frequencies were determined in 8333 volunteer bone marrow donors of Zhejiang Han population using the polymerase chain reaction sequence-based typing. A total of 52 HLA-A, 96 HLA-B and 61 HLA-DRB1 alleles were found. Of these, the top three frequent alleles in HLA-A, HLA-B and HLA-DRB1 loci, respectively, were A*11:01 (24.53%), A*24:02 (17.35%), A*02:01 (11.58%); B*40:01 (15.67%), B*46:01 (11.87%), B*58:01 (9.05%); DRB1*09:01 (17.54%),DRB1*12:02 (9.64%) and DRB1*08:03 (8.65%). A total of 171 A-B-DRB1 haplotypes with a frequency of >0.1% were presented and the five most common haplotypes were A*33:03-B*58:01- DRB1*03:01, A*02:07-B*46:01-DRB1*09:01, A*30:01-B*13:02-DRB1*07:01, A*33:03-B*58:01-RB1*13:02 and A*11:01-B*15:02-DRB1*12:02. The information will be useful for selecting unrelated bone marrow donors and for anthropology studies and pharmacogenomics analysis.

Investigation of killer cell immunoglobulin-like receptors KIR2DL2 and KIR2DL3 diversity and identification of ten novel KIR2DL3 alleles in the Chinese Han population

KIR2DL2 and KIR2DL3 are important inhibitory receptors that recognize a subset of HLA-C allelic products carrying Ser77 and Asn80. In this study, we have determined KIR2DL2 and KIR2DL3 diversity in the Chinese Han population by a PCR sequence-based typing. Based on sequencing, the coding regions of 166 Chinese Han individuals, seven new polymorphic sites (238G>A, 405G>A, 476A>G, 550G>A, 608G>A, 789T>C, 947T>C) were found. KIR2DL2*00301, *00101, KIR2DL3*00101,*00201,*013, *015 and ten new KIR2DL3 variants (KIR2DL3*00105, 00106, 00107, 00108, 019, 020, 021, 022, 023 and 024) were identified, of which KIR2DL3*00101 was the most frequent allele. Compared with the sequences of KIR2DL3*00101, all sequences of 2DL3*00105, 2DL3*00106, 2DL3*00107 and 2DL3*00108 had one nucleotide substitution(789T>C, 261C>T, 489G>A and 405G>A),but none resulted in amino acid change. An A>G substitution was observed in nucleotide position 476 in 2DL3*019, 608 G>A in 2DL3*020, 824T>C in 2DL3*021 and 238 G>A in 2DL3*023. In addition, 2DL3*022 probably arose from 2DL3*00201 with a nucleotide substitution G>A at 550. There were more HLA-C1 positive individuals than HLA-C2. In conclusion, the data of allelic polymorphism for KIR2DL2 and KIR2DL3 were obtained in the Chinese Han population and ten novel KIR2DL3 alleles were identified.

Genomic full-length sequence of a novel HLA-B*39:01:01:03 allele was identified in a Chinese individual

HLA-B*39:01:01:03 allele differs from HLA-B*39:01:01:01 allele by a single nucleotide substitution.

Allelic polymorphism, mRNA and antigen expression of KIR2DL1 in the Chinese Han population

KIR2DL1 is one important molecule of inhibitory receptors that recognizes a subset of HLA-C allelic products carrying Lys80. In this study, we have investigated the allelic polymorphism, mRNA and antigen expression level of KIR2DL1 in the Chinese Han population. KIR2DL1(∗)001,(∗)00302 and (∗)00401 alleles and seven genotypes including two copy 2DL1(∗)00302, one copy 2DL1(∗)00302, two copy 2DL1(∗)001, one copy 2DL1(∗)001, 2DL1(∗)00302/2DL1(∗)001, 2DL1(∗)001/2DL1(∗)00401, 2DL1(∗)00302/2DL1(∗)00401 were identified in the total 164 Chinese Han individuals. The frequency of NK cells expression KIR2DL1 was varied considerably. There was no disparity on the level of antibody-binding for different genotypes according to mean fluorescent intensity and there was almost similar frequency of antibody-binding NK cells except for group KIR2DL1(∗)00302 with one copy. The frequency of NK cells expression KIR2DL1 of the individuals in the group 2DL1(∗)00302 with one copy was lower than that in the group 2DL1(∗)00302 with two copies. The amount of transcript was variable among the individuals and the mean value of transcript abundance in 21 individuals with one copy was lower than that in 143 individuals with two copies. In conclusion, the frequency of NK cells expression KIR2DL1 and the mRNA transcript abundance were not associated with allelic polymorphism but with gene copy number.

HLA-A, HLA-B, HLA-DRB1 allele and haplotype frequencies in 6384 umbilical cord blood units and transplantation matching and engraftment statistics in the Zhejiang cord blood bank of China

Umbilical cord blood (UCB) is a widely accepted source of progenitor cells, and now, many cord blood banks were established. Here, we analysed the HLA-A, HLA-B and HLA-DRB1 allele and haplotype frequencies, HLA matching possibilities for searching potential donors and outcome of UCB transplantations in Zhejiang cord blood bank of China. A total of 6384 UCB units were characterized for 17 HLA-A, 30 HLA-B and 13 HLA-DRB1 alleles at the first field resolution level. Additionally, B*14, B*15 and B*40 were typed to the second field level. A total of 1372 distinct A-B-DRB1 haplotypes were identified. The frequencies of 7 haplotypes were more than 1%, and 439 haplotypes were <0.01%. A*02-B*46-DRB1*09, A*33-B*58-DRB1*03 and A*30-B*13-DRB1*07 were the most common haplotypes, with frequencies of 4.4%, 3.3%, and 2.9%, respectively. Linkage disequilibrium(LD) analysis showed that there were 83 A-B, 106 B-DRB1, 54 A-DRB1 haplotypes with positive LD, in which 51 A-B, 60 B-DRB1, 32 A-DRB1 haplotypes exhibited a significant LD (P < 0.05). In 682 search requests, 12.9%, 40.0% and 42.7% of patients were found to have 6 of 6, 5 of 6 and 4 of 6 HLA-A, HLA-B and HLA-DRB1 matching donors, respectively. A total of 30 UCB units were transplanted to 24 patients (3 patients not evaluated due to early death); 14 of 21 patients (66.7%) engrafted. This study reveals the HLA distribution and its transplantation application in the cord blood bank of Zhejiang province. These data can help to select potential UCB donors for transplantation and used to assess the scale of new cord blood banking endeavours.