A novel HLA-B allele, B*5214, detected in a Taiwanese volunteer bone marrow donor using a sequence-based typing method

Using high-resolution human leukocyte antigen typing of 11,423 randomized unrelated individuals to determine allelic varieties, deduce probable human leukocyte antigen haplotypes, and observe linkage disequilibria between human leukocyte antigen-B and-C and human leukocyte antigen-DRB1 and-DQB1 alleles in the Taiwanese Chinese population

Objective:

We report here the human leukocyte antigen (HLA) allelic variety and haplotype composition in a cohort of the Taiwanese Chinese population and their patterns of linkage disequilibria on HLA-B: HLA-C alleles and HLA-DRB1: HLA-DQB1 alleles at a high-resolution level.

Materials and Methods:

Peripheral whole blood from 11,423 Taiwanese Chinese unrelated individuals was collected in acid citrate dextrose. Genomic DNA was extracted using the QIAamp DNA Blood Mini Kit. The DNA material was subjected to HLA genotyping for HLA-A,-B,-C,-DRB1, and-DQB1 loci using a commercial polymerase chain reaction-sequence-based typing (PCR-SBT) kit, the SeCore^® A/B/C/DRB1/DQB1 Locus Sequencing kit. High-resolution allelic sequencing was performed as previously described.

Results:

The number of individual HLA-B alleles detected was greater than the number of alleles recognized in the both the HLA-A and-DRB1 loci. Several novel alleles were discovered as a result of employing the SBT method and the high number of donors tested. In addition, we observed a genetic polymorphic feature of association between HLA-A and-B, HLA-B and-C, and HLA-DRB1 and-DQB1 alleles. Further, the homozygous haplotype frequencies of HLA-A and-B; HLA-A,-C, and-B; HLA-A,-C,-B, and-DRB1; and HLA-A,-C,-B,-DRB1, and-DQB1 in Taiwanese Chinese population are presented.

Conclusion:

As increasing number of HLA alleles are being discovered, periodic HLA profile investigation in a given population is essential to recognize the HLA complexity in that population. Population study can also provide an up-to-date strategic plan for future needs in terms of compatibility measurement for HLA matching between transplant donors and patients.

Discovery of the rare HLA-B*39:77 allele in an unrelated Taiwanese bone marrow stem cell donor using the sequence-based typing method

We detected a rare HLA-B locus allele, B*39:77, in a Taiwanese unrelated marrow stem cell donor in our routine HLA sequence-based typing (SBT) exercise for a possible haematopoietic stem cell donation. In exons 2, 3 and 4, the DNA sequence of B*39:77 is identical to the sequence of B*39:01:01:01 except one nucleotide at nucleotide position 733 (G->A) in exon 4. The nucleotide variation caused one amino acid alteration at residue 221 (Gly->Ser). B*39:77 was probably derived from a nucleotide substitution event involving B*39:01:01:01. The probable HLA-A, -B, -C, -DRB1 and -DQB1 haplotype in association with B*39:77 may be deduced as A*02:01-B*39:77-C*07:02-DRB1*08:03-DQB1*06:01. Our discovery of B*39:77 in Taiwanese adds further polymorphism of B*39 variants in Taiwanese population.

Identification of the novel HLA-B*40:221 allele in a Taiwanese hematopoietic stem cell donor using a sequence-based typing method

Using DNA sequence-based typing method, we found a new HLA-B*40 variant, B*40:221, in a Taiwanese hematopoietic stem cell donor. The allele sequence of B*40:221 is identical to the sequence of B*40:01:01 in exons 2, 3 and 4 except the nucleotides at codon 265 (GGG→AGG). The sequence variation caused one amino acid exchange at residue 265 where Gly was replaced by Arg. The probable HLA-A, -B, -C, -DRB1 and -DQB1 haplotype in association with B*40:221 may be deduced as HLA-A*11:01-B*40:221-C*03:04-DRB1*14:54-DQB1*05:02. The generation of B*40:221 is thought as a result of a nucleotide point mutation involving B*40:01:01. Our discovery of B*40:221 increases the polymorphism of B*40 in Taiwanese.

A conserved HLA-A*02:28 associated HLA haplotype, A*02:28-B*15:11-DRB1*09:01, restricted to Taiwanese

HLA-A*02:28, found in a Korean and a Japanese, was reported independently to the IMGT/HLA database in 2003 and 2005, respectively. We report here eight Taiwanese unrelated bone marrow hematopoietic stem cell donors carrying A*02:28 detected during our routine HLA typing exercise. The probable HLA-A, -B and -DRB1 haplotype in association with A*02:28 may be deduced from the eight marrow stem cell donor as A*02:28-B*15:11-DRB1*09:01. Our result suggests A*02:28-B*15:11-DRB1*09:01 is a conserved HLA haplotype restricted to Taiwanese.

Identification of the novel HLA-B*13:02:13 allele in a Taiwanese haematopoietic stem cell donor and the probable HLA haplotype in association with B*13:02:13

Using sequence-based typing method, we found a new HLA-B*13:02 variant, B*13:02:13, in a Taiwanese haematopoietic stem cell donor. The DNA sequence of B*13:02:13 is identical to the sequence of B*13:02:01 in exons 2 and 3 except the nucleotide at position 588 where G is replaced by T (codon 172; CTG→CTT). The DNA sequence variation did not alter the amino acid sequence of B*13:02:01. The generation of B*13:02:13 is thought to derive from B*13:02:01 as a result of a silence mutation. The probable HLA-A, HLA-B and HLA-DRB1 haplotype in association with B*13:02:1 may be deduced as HLA-A*24-B*13:02:13-DRB1*07:01 or HLA-A*02-B*13:02:13-DRB1*07:01. The discovery of B*13:02:13 furthers the polymorphism of HLA-B*13 and HLA-B*13:02.

Recognition of a Caucasoid HLA-B locus allele, B*44:55, in a Taiwanese/Chinese bone marrow stem cell donor

We detected a Caucasoid HLA-B allele, HLA-B*44:55, in a potential Taiwanese/Chinese bone marrow hematopoietic stem cell donor during our routine HLA SBT (sequence-based typing) practice. The sequence of B*44:55 varies with B*44:02:01:01 with one nucleotide in exon 2 at position 97 (T->C), while it differs from B*44:03:01 with one nucleotide in exon 2 at position 97 (T->C) and three nucleotides in exon 3 at residues 538-540 (CTG->GAC). The nucleotide replacements caused one amino acid variation with B*44:02:01:01 at residue 9 (Y->H) and two amino acid variations with B*44:03:01 at residue 9 (Y->H) and residue 156 (L->D). The formation of B*44:55 is probably the result of a nucleotide substitution involving B*44:02:01:01 at position 97 (T->C). The Taiwanese/Chinese donor with B*44:55 claims having no kinship with Caucasian. Our speculations on the origin of the Taiwanese/Chinese B*44:55 will be presented.

Detection of the rare HLA-B*40:97 allele in an unrelated Taiwanese bone marrow donor

We detected a rare HLA-B locus allele, B*40:97, in a Taiwanese unrelated donor in our routine HLA SBT (sequence-based typing) exercise for a possible hematopoietic stem cell donation. In exons 2, 3 and 4, the sequence of B*40:97 is identical to the sequence of B*40:02:01 except one nucleotide at nucleotide position 760 (C->T) in exon 4. The nucleotide variation caused one amino acid alteration at residue 230 (L->F). B*40:97 was probably derived from a nucleotide substitution event where C was replaced by T at nucleotide 760 involving B*40:02:01. The HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 haplotype in association with B*40:97 may be deduced as A*26:01-B*40:97-C*03:03-DRB1*11:01-DQB1*03:03. Our recognition of B*40:97 in Taiwanese helps to fill the void of ethnic information for the allele B*40:97 reported to the IMGT/HLA Database.

Recognition of HLA-A*24:137 allele in a Taiwanese unrelated bone marrow stem cell donor and the plausible HLA haplotype associated with A*24:137

We detected a rare HLA-A*24:137 allele in an unrelated Taiwanese haematopoietic stem cell donor during a routine SBT (sequence-based typing) HLA typing exercise. The DNA sequence of A*24:137 is identical to the sequence of A*24:02:01:01 in exons 2 and 3 except at codon 21 where CGC was replaced with CAA. The DNA variation caused an amino acid alteration at amino acid residue 21 (R->Q). The HLA haplotype in association with A*24:137 may be deduced as A*24:137-B*15-DRB1*14. The formation of A*24:137 was probably the result of a nucleotide point mutation involving A*24:02:01:01. It remains to be determined whether A*24:137 is restricted to Taiwanese/Chinese ethnicity.

Discovery of the novel HLA-DRB1*16:16 allele in a Taiwanese unrelated bone marrow stem cell donor by a sequence-based typing method and the probable haplotype associated with DRB1*16:16

We report here a de novo HLA-DRB1 allele, DRB1*16:16, discovered in a Taiwanese unrelated volunteer bone marrow stem cell donor by a sequence-based typing (SBT) method. In exon 2, the DNA sequence of DRB1*16:16 is identical to the sequence of DRB1*16:02:01 except the nucleotides at positions 258 (C→T), 260 (C→A) and 261 (T→G). The nucleotide substitution produced an amino acid replacement at residue 58 (A→E). The formation of DRB1*16:16 was probably generated by a DNA sequence recombination event involving DRB1*11:01:01 and DRB1*16:02:01. The probable HLA-A, -B and -DRB1 haplotype in association with DRB1*16:16 may be deduced as A*02-B*38-DRB1*16:16.

Identification of two novel HLA-A*02 variants, A*02:319 and A*02:01:64, in two Taiwanese marrow stem cell donors by sequence-based typing

We report here two novel variants of HLA-A*02 allele, A*02:319 and A*02:01:64, discovered in two Taiwanese unrelated volunteer bone marrow donors by sequence-based typing (SBT) method. The DNA sequence of A*02:319 is identical to A*02:07 in exons 2 and 3 but varies with one nucleotide at codon 9 (TTC->TCC). The variation caused one amino acid substitution at residue 9 (F->S). On the other hand, the DNA sequence of A*02:01:64 is identical to the sequence of A*02:01:01:01 in exons 2 and 3 except a silent mutation at codon 114 (CAC->CAT). The probable HLA-A, HLA-B and HLA-DRB1 haplotypes in association with A*02:319 and A*02:01:64 were deduced as A*02:319-B*46:01-DRB1*04 and A*02:01:64-B*38:02-DRB1*16:02, respectively.

Discovery of two novel HLA-B alleles, B*46:13:03 and B*15:189, in two Taiwanese volunteer bone marrow donors by sequence-based typing

We report here two novel HLA-B alleles, B*46:13:03 and B*15:189, discovered in two Taiwanese volunteer bone marrow donors. The sequence of B*15:189 has a nucleotide sequence possibly derived from a recombination event between HLA-B*39:01:01 and B*15:01:01:01, while the origin of the sequence B*46:13:03 was less obvious to postulate, considering the low frequency of B*46:13 in the general population and the silent mutations involved. Our report here adds further HLA polymorphism to the growing lists of HLA-B*46 and HLA-B*15 and provides an additional HLA information for donor search programme for patients undergoing transplant.

Oriental HLA-A*11:90 detected in a Taiwanese cord blood sample and the haplotype in association with A*11:90 allele

We report here an HLA-A allele, A*11:90, found in a Taiwanese cord blood sample using DNA sequence-based typing (SBT) protocol after observing an anomalous reaction pattern in a sequence-specific oligonucleotide (SSO) typing exercise. The sequence of A*11:90 is identical to A*11:01:01, the most predominant A*11 variant in Taiwanese, in exon 2 but differs from A*11:01:01 in exon 3 by two nucleotide substitutions at codon 163 (c.487C>G and c.488G>A), resulting R163E. In comparison with the sequence of A*11:02:01, the second most predominant subtype of A*11 in Taiwanese A*11:90 has one nucleotide difference at codon 19 (c.55A>G) in exon 2 resulting K19E and two nucleotides variations at codon 163 (c.487C>G and c.488G>A) in exon 3 resulting R163E. HLA-A*11:90-B*40:02-DRB1*11:01 is the deduced probable HLA haplotype in association with A*11:90. The generation of A*11:90 is thought to involve a DNA recombination event between alleles A*11:01:01 and A*80:01 where A*80:01 donated a fragment of the DNA sequence (from n.t. 487 to n.t. 497) to the recipient sequence of A*11:01:01.

Detection of two HLA-A alleles, A*31:30 and A*26:20, in two Taiwanese volunteer bone marrow donors by sequence-based typing

We here report detection of a novel sequence of HLA-A*31:30 and a confirmatory sequence of HLA*26:20 from two Taiwanese individuals. The sequence of A*31:30 is identical to that of A*31:01:02 in exons 2 and 3, except one nucleotide (n.t.) substitution c.539T > G resulting in p.Leu180Trp. The sequence of A*26:20 is identical to A*26:01:01 in exons 2 and 3, except a segment of the sequence from n.t. 78 to n.t.102. The mismatched sequence segment is identical to a sequence segment of A*02:03:01, suggesting that the formation of A*26:20 was resulted from a DNA recombination event between A*26:01:01 and A*02:03:01 sequences. A*26:20 differs from A*26:01:01 with c.98A > T resulting in p.Tyr33Phe.