Identification and sequencing of HLA-B*0714 and B*2718 alleles and novel exon 1 sequences of B*0709 and B*2714 alleles in potential bone marrow donors

Sequence specific oligonucleotide probe hybridization and sequence specific primer PCR typing of volunteer bone marrow donors suggested the presence of variants of known HLA-B alleles in two individuals. PCR products encompassing HLA-B locus exons 1, 2, and 3 were prepared, subcloned and sequenced. A Hispanic individual had a novel B*07 allele (B*0714) and a Chinese individual had a novel B*27 allele (B*2718). In two other individuals, a previously unknown sequence of exon 1 was determined for HLA-B*0709 (African American) and B*2714 (Native American). These findings further illustrate the substantial genetic variation present at the HLA-B locus within human populations. We discuss the structural variation in the protein sequence for these HLA-B alleles and its potential functional effects.     

Novel HLA-B alleles identified in potential marrow donors: B*3917, B*1405 and B*3528

Sequence-specific oligonucleotide probe hybridization and sequence-specific primer polymerase chain reaction (PCR) typing of volunteer bone marrow donors suggested the presence of variants of known HLA-B alleles in five individuals. PCR products encompassing HLA-B locus exons 1 through 3 were prepared and subcloned. Three African-American individuals had a novel HLA-B*39 allele (B*3917), and another African-American was found to have a novel HLA-B*14 allele (B*1405). In a third individual of Hispanic origin, a novel HLA-B*35 allele (B*3528) was identified. These findings further illustrate the substantial genetic variation present at the HLA-B locus within human populations.     

Novel HLA-B alleles, B*8201, B*3515 and B*5106, add to the complexity of serologic identification of HLA types

Three class I alleles, B*8201, B*3515 and B*5106, have been described using DNA and cDNA sequencing. The B*8201 allele is most structurally related to B*5602, differing from it by 14 nucleotide substitutions resulting in 5 amino acid differences. The other two alleles, B*3515 and B*5106, differ from their most closely related HLA-B alleles by 2–3 nucleotide substitutions resulting in 1–2 amino acid substitutions, respectively. The majority of nucleotide substitutions marking these new alleles are observed in other HLA-B alleles suggesting that gene conversion and/or reciprocal recombination have created this diversity. All of the amino acid substitutions are predicted to alter the antigen binding site of the HLA-B molecule. The newly defined HLA-B allelic products were originally defined by their unusual serologic reactivity patterns. The B*8201 allelic product is serologically typed as a B "blank" or as a variant of B22 or B45. These patterns and the serologic reactivity of the other newly described allelic products are consistent with the protein sequence homology among specific HLA-B molecules. While serology remains a powerful tool for detecting HLA diversity, alleles generated by events resulting in the sharing of HLA sequence polymorphisms among alleles at a locus will continue to create complexity in the interpretation of typing results.     

Identification of two new HLA-B22 variants, HLA-B*5509 and B*5606

In our recent study using high-resolution HLA-B locus typing by sequence-based typing (SBT) we identified 9 new alleles in a total of 355 unrelated individuals (4). Three of them concerned an allele belonging to the B22 group. One of them, B*5607, showed the unusual presence of a Bw4 sequence motif, as described previously (5). In this report the other two B22 variants are described; one belonging to the B55 specificity and named B*5509; the other one being a B*56 allele and assigned B*5606, which brings the total number of alleles belonging to the B22 group to 18.     

Identification of a new HLA-B*08 variant, HLA-B*0804

The HLA-B locus is the most polymorphic locus known with currently over 100 different alleles described. Many of these alleles encode variants of the serologically-defined tissue transplantation antigens. This high level of diversity makes accurate tissue typing difficult. Here we present the sequence of a new HLA-B *08 variant, HLA-B *0804. found in Caucasian siblings JH and PF serologically typed as HLA-B51/B59 and HLA-B59/B60, respectively. Additionally, DNA-based typing by the polymerase chain reaction using sequence-specific primers (PCR-SSP) identified HLA-B *51 in JH and HLA-B *4001 in PF. However, PCR-SSP failed to identify a second allele in either of these individuals. The unusual finding of a B59 antigen in a Caucasian and the discrepant molecular typing results suggested that these individuals might express novel HLA molecules. Using denaturing gradient gel electrophoresis (DGGE) followed by direct sequencing, we characterized a novel HLA-B *08 variant, HLA-B *0804. The presence of this allele was confirmed by cloning and sequencing. HLA-B *0804 differed from HLA-B *0801 by only one nucleotide substitution resulting in an amino acid replacement of phenylalanine by serine at position 67. Incidentally, this single nucleotide difference was sufficient to prevent amplification by PCR-SSP. This striking difference between both the serologically typed antigen and the PCR-SSP-identified allele compared to the sequenced allele supports the use of sequence-based typing for the analysis of HLA class I locus alleles.     

A novel HLA-B*40 allele and novel exon 1 sequences of two B*40 alleles identified in potential marrow donors

Sequence-specific oligonucleotide probe hybridization and sequence-specific primer polymerase chain reaction (PCR) typing suggested the presence of variants of HLA-B*40 in three individuals. Two were part of 3,500 potential marrow donors being screened for the National Marrow Donor Program, while the third was a clinical specimen. PCR products encompassing HLA-B locus exons 1 through 3 were prepared and subcloned. In one individual, a native of the Pacific Islands, sequencing revealed a novel HLA-B*40 allele (B*4023). In two other individuals, a previously unknown exon 1 sequence was determined for HLA-B*4016 (ethnicity unknown) and B*4020 (Hispanic). These findings further illustrate the substantial genetic variation present at the HLA-B locus within human populations.     

Definition of a new HLA-B7 subtype (B*0704) by isoelectric focusing, family studies and DNA sequence analysis

Abstract: During screening of potential bone marrow donors, a previously undescribed banding position for the serologically defined HLA-B7 antigen was identified in three unrelated families using one dimensional isoelectric focusing and class I specific Western blot analysis. The isoelectric point of the new variant is more acidic than the two HLA-B7 variants that had been defined before. In each family the new B7 variant was found linked to HLA-A2 and -Cw7. Cloning and sequencing of full-length clones of complementary DNA showed that the new allele (B*0704) differs from B*0702, the common allele encoding HLA-B7, by three nucleotide substitutions within the codon for residue 156 of the mature heavy chain. As a result of these differences amino acid 156 is changed from arginine to aspartic acid, a difference consistent with the isoelectric points. The group of three nucleotide substitutions that distinguish B*0704 from B*0702 is present in other HLA-B alleles.     

Identification of the novel allele B*4427 and a confirmatory sequence (B*44022)

This report presents a novel allele, HLA-B*4427, which was identified in a bone marrow donor of Caucasian origin, and a confirmatory sequence (B*44022). Sequence analysis revealed the new allele differs from B*44021 by a single nucleotide exchange at position 668 (C-->T), which is located in exon 4. At the protein level, it is the only B*44 variant to produce an Ala in place of a Val at codon 199. Its structure suggests that it may have originated from a point mutation in B*44021 or by gene conversion with a variety of HLA-B alleles. Cloning and sequencing of the allele B*44022 revealed a sequence identical to B*44021 and B*44 exon 4, with the codon GTC (Val) in position 199.     

Novel HLA-B alleles formed by an inter-locus recombination with HLA-C,HLA-B*0713 and B*6702

This paper describes two novel HLA-B locus alleles. B*0713 appears to have resulted from an interlocus recombinational event which inserted a sequence from an HLA-C allele into B*0702. This event altered a significant portion of the alpha-1 domain alpha helix. B*6702 shares much of its exon 2 sequence with B*0713 but is identical in exon 3 to several HLA-B locus alleles including B*67012.     

Identification of a novel HLA-B*07 allele--HLA-B*0726

We describe here, the identification of a novel HLA-B*07 allele named HLA-B*0726. This allele was found in a Caucasian individual serologically typed as HLA-B7, B35. Novel DNA probe patterns for the HLA-B*07 allele were found using HLA-B specific reverse sequence-specific oligonucleotide probe (SSOP) and sequence-specific primer (SSP) typing. DNA sequencing demonstrated the presence of a new HLA-B*07 sequence variant encoding a single nucleotide substitution from a G to a T at nucleotide 539 in exon 3. This results in an amino acid substitution from arginine to leucine at residue 156 in exon 3.     

Identification of the novel allele HLA-B*0809 in a Caucasian individual: estimation of allogeneic potential between B*08 variants

The identification of the new allele HLA-B*0809, which was found in a Caucasian individual, is described. In the sequence analysis the new allele differs from B*0801 by six nucleotides located in exon 3. As the structure is identical to a variety of other HLA-B alleles, it is likely that the new allele originated by gene conversion. At the protein level, the new allele has two amino acid differences compared to B*0801. Comparing the residues of the alpha1 and alpha2 domains of the B*08 variants to each other, a high degree of polymorphism was found. Three alleles differ from B*0801 by only one amino acid residue whereas the other comparisons revealed at least two disparities. B*0809 differs from the other B*08 variants by at least two amino acid residues, suggesting that mismatching may provoke alloreactivity and thus impair clinical outcome of bone marrow transplantation. Among the B*08 alleles with a single amino acid difference, the mismatch combinations B*0801 vs. B*0805 and B*0801 vs. B*0807 appear to be the most compatible based on structural data.     

A novel HLA-B*420502 allele identified by PCR-SSO/SSP routine typing and confirmed by Sequencing-based typing

A novel human leukocyte antigen-B (HLA-B) allele, B*420502, was identified in a patient with leukemia (Caucasoid, Czech ancestry) and his mother during intrafamily search for the hematopoietic stem cell donor. The novel allele was initially detected by HLA typing at low resolution using both sequence specific primers and sequence specific oligonucleotides techniques that resulted in unique reaction patterns. The alleles of the HLA-B locus were separated by the haplotype-specific extraction technique. Sequencing of those alleles revealed a novel allele, B*420502, that is identical with B*420501 except a T-->G exchange (synonymous mutation) at position 618.     

Diversity is demonstrated in class I HLA-A and HLA-B alleles in Cameroon, Africa: description of HLA-A*03012, *2612, *3006 and HLA-B*1403, *4016, *4703

To examine the genetic diversity in west Africa, class I HLA-A and HLA-B alleles of 92 unrelated individuals from two areas in the Cameroon, the capital Yaoundé and the village of Etoa, were identified by direct automated DNA sequencing of exons 2 and 3 of the HLA-B locus alleles and sequence-specific oligonucleotide probe (SSOP) and/or sequencing of the HLA-A locus alleles. HLA-A*2301 (18.7%), A*2902 (10.4%), B*5301 (10.9%), and B*5802 (10.9%) were the most frequently detected alleles, present in at least 10% of the population. A total of 30 HLA-A locus and 33 HLA-B locus alleles, including six novel alleles, were detected. The novel alleles were HLA-A*03012, A*2612, A*3006 and HLA-B*1403, B*4016, and B*4703. HLA-B*4703 contains a novel amino acid sequence that is a combination of the first 5 amino acids of the Bw6 epitope and the last 2 residues of the Bw4 epitope. The addition of 6 alleles to the ever-expanding number of known class I HLA alleles supports our hypothesis that extensive genetic diversity, including previously undescribed alleles, would be observed in this African population. In the Yaoundé population, the allele frequency distribution at the HLA-A locus is consistent with distributions indicative of balancing selection. Extensive HLA-A-B haplotypes were observed in this population suggesting that only a fraction of the Cameroon HLA-A-B haplotype diversity has been observed.     

Identification of two new alleles in a single Korean individual,HLA-B*1568 and HLA-DRB1*1208

We have identified a new HLA-B*15 allele and a new HLA-DRB1*12 allele, named B*1568 and DRB1*1208, respectively. The alleles were identified using a combination of sequence specific primers, reverse line sequence specific oligonucleotide probing and sequence-based typing. Both alleles were identified in a single individual of Korean origin. HLA-B*1568 appears to be an HLA-B*4801/B*1507 hybrid combining the exon 2 sequence of B*4801 and the exon 3 and 4 sequences of B*1507. Exon 2 of DRB1*1208 was most similar to DRB1*1201 or 1206, with a single mismatch at nucleotide position 165 (A to C). At the protein level, this substitution results in a phenylalanine substitution at position 26 that creates an identical amino acid sequence to DRB3*0202 between amino acid positions 17 and 36.     

用等位基因组特异性引物扩增技术确认HLA-B新等位基因B*15:129

目的 对人类白细胞抗原(human leukocyte antigen,HLA)新等位基因HLA-B*15:129的第2～4外显子序列进行分析.方法 采用商用抽提试剂盒抽提标本DNA,应用等位基因组特异性引物PCR方法扩增先证者标本HLA-B基因第2～4外显子,PCR产物经酶切纯化后直接进行HLA-B基因第2～4外显子双向测序分析.结果 先证者标本存在2个HLA-B等位基因,1个等位基因为B*07:02,另1个经Blast验证为新的等位基因,新的等位基因序列已递交GenBank(EF473219),经世界卫生组织HLA命名委员会正式命名为HLA-B*15:129.HLA-B*15:129第2～4外显子序列与最接近的B*15:01:01:01相比,第3外显子存在3个碱基的不同,即第362位G→A、363位G→T、369位C→T改变,导致第97位氨基酸Arg→Asn.结论 发现1例新的HLA-B等位基因,被世界卫生组织HLA基因命名委员会正式命名为HLA-B*15:129.

Abstract：

Objective To analyze the sequence of the exons 2-4 of human leukocyte antigen (HLA) novel allele HLA-B*15:129.Methods DNA of the proband was extracted from whole blood by commercial DNA extraction kit. The amplification for HLA-B exons 2-4 was performed separately by polymerase chain reaction (PCR) with allele group specific primers. The PCR products were digested with enzymes and then directly sequenced for exons 2-4 of HLA-B locus in both directions.Results Sequencing results showed the HLA-B alleles of the proband included B*07:02 and a novel allele. The sequence of the novel allele has been submitted to GenBank (accession no. EF473219) and the allele has been officially named B*15:129 by the WHO Nomenclature Committee. Comparing with the HLA-B*15:01:01:01, the sequence of exons 2-4 of HLA-B*15:129 showed three nucleotide difference in exon 3 at positions 362 and 363 from GG to AT and positions 369 from C to T, which resulted in an amino acid change from Arg to Asn at codon 97.Conclusion A novel HLA-B allele was identified and has been officially named B15:129 by the WHO Nomenclature Committee.     

HLA-B16 antigens: sequence of the ST-16 antigen, further definition of two B38 subtypes and evidence for convergent evolution of B*3902

Abstract: The ST-16 antigenic specificity of the HLA-B locus is defined as a B39 variant of Mexican-Americans. Nucleotide sequencing of cDNA shows the ST-16 allele (B*3905) differs from B*39011 by a single substitution that substitutes tyrosine for aspartic acid at position 74 of the mature class I heavy chain. The complete coding region sequence for the common caucasoid allele encoding the B38 antigen has been determined. This B*3801 allele differs from B*3802 at two nucleotide substitutions within the Bw4 sequence motif. B*3801 and B*3802 may have been derived independently from B*39011 by conversion events with B alleles donating distinctive Bw4 motifs. A novel allele B*39022 derived from a Colombian Indian differs from the B*39021 allele of Japanese origin at two widely separated silent substitutions. Comparison of sequences for the known B16 alleles suggest that B*39021 and B*39022 were independently derived by recombination from B*39013 and B*39011 respectively.     

A novel HLA allele, B*4104, identified in a cord blood donor

Results from a number of HLA typing methods prompted the DNA sequencing (SBT) of a cord blood sample at the HLA-B locus. A novel HLA-B allele, B*4104, was identified. This was confirmed by sequencing the mother of the cord blood unit for HLA-B.     

HLA新等位基因B*5827核苷酸序列的分析

目的 确认人类白细胞抗原(human leukocyte antigen,HLA)新等位基因B*5827并分析其核苷酸序列.方法 用聚合酶链反应-序列特异性寡核苷酸探针对1份HLA分型反应异常的血样进行基因分型,并用基因克隆测序技术正反向测定DNA序列.结果 测序结果显示HLA-B位点有1个与已知HLA等位基因序列均不同的新等位基因,该等位基因与HLA-B*5820序列同源性最高.但在第3外显子存在8个碱基的差异,分别为nt 290(G＞C)、nt 346(T＞A)、nt 390(A＞C)、nt 404(G＞C)、nt 413(C＞G)、nt 471(A＞G)、nt 486(A＞G)和nt 487(C＞A).碱基的不同导致了氨基酸不同nt 97(ser＞arg)、nt115(phe＞tyr)、nt 130(ser＞arg)、nt 157(thr＞ala)和nt 162(thr＞glu),其中nt 404和nt 413是同义突变.结论 该等位基因为HLA新等位基因,基因序列已提交至GenBank数据库,提交号为GU071234,于2010年1月被世界卫生组织HLA因子命名委员会正式命名为HLA-B*5827.

Abstract：

Objective To investigate the molecular basis for a novel human leukocyte antigen(HLA)allele B * 5827. Methods DNA from the proband was analyzed by polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) typing. The amplified product was sequenced bidirectionally. Results Abnormal HLA-B locus was observed and its nucleotide sequence was different from the known HLA-B allele sequences, with highest homology to HLA-B * 5820 allele. It differs from HLA-B * 5820 by 8 nucleotide substitutions in exon 3, i. e. , nt 290 (G＞C), nt 346 (T＞A), nt 390 (A＞C), nt 404 (G＞C),nt 413 (C＞G), nt 471 (A＞G), nt 486 (A＞G) and nt 487 (C＞A), resulting in an amino acid change from ser＞arg at nt 97, phe＞tyr at nt 115, ser＞arg at nt 130, thr＞ala at nt 157 and thr＞glu at nt 162.Nucleotide differences of nt 404(G＞C) and nt 413(C＞G) did not change amino acid. Conclusion The sequences of the novel allele have been submitted to GenBank (access No. GU071234). A novel HLA class Ⅰ allele B * 5827 has been officially assigned by the WHO HLA Nomenclature Committee in Jan 2010.     

HLA-B*4431: a new HLA-B variant with a complex ancestral history involving HLA-B*44, B*40 and B*07 alleles

We here describe the identification of the new allele HLA-B*4431, which was found in three members of a Turkish family. Sequencing of the new allele following haplotype-specific PCR amplification revealed that exon 2 is identical to HLA-B*4402, whereas exon 3 resembles a HLA-B*40 variant with the exception of position 572, where a single nucleotide transversion (C > G) leads to an amino acid exchange (Trp162Ser). The generation of the 3' part of B*4431 may be best explained by a separate recombination between B*40 and B*07. Although B*4431 consists of B44 in its alpha1 domain and of B60(40) in its alpha2 domain; the new allele only displayed B44 seroreactivity, which demonstrates that epitopes crucial for B60(40) specificity must be located in the alpha1 domain.     

HLA-B新等位基因B*9536和B*4612的测序分析和确认

目的 研究人类白细胞抗原(human leukocyte antigen,HLA)新等位基因HLA_B*9536和B*4612的分子机制.方法 采用Invitrogen抽提试剂盒抽提标本DNA,利用单链特异性引物PCR方法扩增样本HLA-B基因第2～4外显子,对PCR产物直接进行HLA-B基因第2、3、4外显子双向测序分析.结果 先证者标本存在2个HLA-B等位基因,经HLA Blast验证均为新的等位基因,新的等位基因序列已递交GenBank(EU081878和EU081879),经世界卫生组织HLA命名委员会正式命名为HLA-B*9536和HLA-B*4612.HLA-B*9536第2～4外显子序列与最接近的B*1505相比,在第3外显子存在一个碱基的不同,即第544位G→A改变,导致第158位氨基酸Ala→Thr;HLA-B*4612第2～4外显子序列与最接近的B*4601相比,在第3外显子存在一个碱基的不同,即第363位G→C,导致第97位氨基酸Arg→Ser.结论 在同一标本中发现两个新的HLA-B等位基因,并被世界卫生组织HLA命名委员会正式命名.