HLA-B*5603: sequence of a novel hybrid allele comprising B*56 and B*4601 segments

Confirmation of a recombinant allele B*5603 and a hypothetical reciprocal hybrid

From its DNA sequence, B*5603 is thought to be a product of gene conversion. We present here serological evidence of such an event and further speculate on a possible reciprocal hybrid yet to be identified. In addition, we report the allelic frequency of B*5603 in the Taiwanese population and its association with A*1101, Cw*01 and DRB1*1201.

HLA-B*4021: hybrid linking the B15 and B40 families

Twenty alleles encoding molecules with the B60 or B61 serologic specificity have been reported thus far. This study characterized a new allele encoding a molecule exhibiting partial serologic reactivity with B15- and B40-related alloantisera from unrelated Korean individuals. Based on the DNA sequence, it appears that the novel allele has a sequence identical to some of alleles in B*15 family including B*1501 in exon 2. The sequence in exon 3, however, is identical to alleles in the B*40 family (B*4001/07/10/12) and B*4803. This implies that the novel allele, B*4021, has evolved by a reciprocal gene recombination involving members of these two families. The haplotype associated with B*4021 is likely to be A11-Cw4-B*4021-DRB1*04-DRB4*01-DQA1*03-DQB1*0301 .

The HLA dictionary 1999: a summary of HLA-A, -B, -C, -DRB1/3/4/5, -DQB1 alleles and their association with serologically defined HLA-A, -B, -C, -DR, and -DQ antigens

This report presents serologic equivalents of 90 HLA-A, 190 HLA-B, and 145 HLA-DRB1 alleles. The equivalents cover over 70% of the presently identified HLA-A, -B, and -DRB1 alleles. The dictionary is an update of the one published in 1997 and now also includes equivalents for HLA-C, DRB3, DRB4, DRB5, and DQB1 alleles. The data summarize information obtained by the WHO HLA Nomenclature Committee, the International Cell Exchange (UCLA), the National Marrow Donor Program (NMDP), and by individual laboratories. In addition, a listing is provided of alleles that are expressed as antigens with serologic reaction patterns that differ from the well-established HLA specificities and that often lack official WHO nomenclature. The provided equivalents will be useful in guiding searches for unrelated donors in which patients and/or potential donors are typed by either serology or DNA-based methods. These equivalents will also serve typing and matching procedures for organ transplant programs where HLA typings from donors and from recipients on waiting lists represent mixtures of serologic and molecular typings. Some guidelines are provided for the use of appropriate WHO HLA nomenclature for serologic typings and for generic and allele specific typings obtained with molecular methods. The tables with HLA equivalents and the questionnaire for submission of serology on poorly identified alleles will also be available at the WMDA web page: www.bmdw.org/wmda.

The HLA dictionary 1999: a summary of HLA-A, -B, -C, -DRB1/3/4/5, -DQB1 alleles and their association with serologically defined HLA-A, -B, -C, -DR and -DQ antigens

This report presents serologic equivalents of 90 HLA-A, 190 HLA-B and 145 HLA-DRB1 alleles. The equivalents cover over 70% of the presently identified HLA-A, -B and -DRB1 alleles. The dictionary is an update of the one published in 1997 and now also includes equivalents for HLA-C, DRB3, DRB4, DRB5 and DQB1 alleles. The data summarize information obtained by the WHO HLA Nomenclature Committee, the International Cell Exchange (UCLA), the National Marrow Donor Program (NMDP) and by individual laboratories. In addition, a listing is provided of alleles which are expressed as antigens with serologic reaction patterns that differ from the well-established HLA specificities and that often lack official WHO nomenclature. The provided equivalents will be useful in guiding searches for unrelated donors in which patients and/or potential donors are typed by either serology or DNA-based methods. These equivalents will also serve typing and matching procedures for organ transplant programs where HLA typings from donors and from recipients on waiting lists represent mixtures of serologic and molecular typings. Some guidelines are provided for the use of appropriate WHO HLA nomenclature for serological typings and for generic and allele specific typings obtained with molecular methods. The tables with HLA equivalents and the questionnaire for submission of serology on poorly identified alleles will also be available at the WMDA web page: www:bmdw.org/wmda.

HLA-B22 diversity including a novel B54 variant (B*5507) in the Korean population

Diversity in the HLA-B22 group was investigated in the Korean population using PCR-SSOP and DNA sequencing analyses. Allelic typing of the B22 gene was performed by gene amplification of the polymorphic exons 2 and 3 of the HLA-B genes from 91 B22 positive individuals followed by a hybridization assay using 63 digoxigenin-labelled probes. Five different SSOP patterns including an unexpected pattern were identified and correlated well with the observed serologic types and with data obtained from DNA sequencing analyses. Novel allele, B*5507, was identified from two unrelated individuals who exhibited standard B54 serologic reactivity but an unexpected SSOP pattern. The DNA sequence of B*5507 is identical to B*5502 in exons 2 and 3 except for a single nucleotide substitution at codon 45 (GAG-->GGG) altering glutamic acid to glycine. Among the already known B molecules, this substitution has been observed only in the B54 molecule encoded by B*5401 allele. This is the evidence that Gly-45 is a crucial site forming the B54 serologic epitope. Interestingly, both alleles (B*5401 and B*5507) exhibit strong association with Cw*0102. Along with previous data, B22 appears to be a very diverse group in the Korean population consisting of at least seven different alleles. B*5401, B*5502, and B*5601 are the most frequent alleles. B*5507, B*5501, B*5504, and B*5604 appear at lower frequencies. Data obtained from this study will be useful in hematopoietic stem cell donor searches as well as in determination of a typing strategy for the HLA-B22 types in this population.

Novel HLA-A and HLA-B alleles

Nine novel HLA-A and HLA-B alleles are described: A*2609, A*6803, A*6806, B*1539, B*1540, B*2712, B*4103, B*5109, and B*5603. Most appear to have arisen by gene conversion events. B*5603 appears to have arisen by a reciprocal recombination event joining exon 2 of a B*55/ *56 allele with exon 3 of a B*15 allele. Serologically, the antigen encoded by this allele types with broad B22- and Bw6-specific alloantisera. Also unique, the antigen encoded by B*2712 does not react with B27-specific alloantisera but does react with Bw6-specific alloantisera.

Allele-specific HLA-B*15 typing by PCR-SSP and its application to four distinct ethnic populations

We present a set of primer mixes for the allele-specific typing of the HLA-B*15 group by PCR-SSP. The set comprises 46 primer mixes which are designed to unequivocally resolve all but two of the 666 possible combinations of the B*15 alleles, B*1501-37 (B*1536 sequence unavailable). A core subset of 34 of the 46 mixes can be used alone to give a high resolution B*15 typing set. This allows for the identification of each B*15 allele when present as the only B*15 allele and the majority of the possible B*15 homozygotic combinations. The method was validated using reference DNA samples and the B*15 allele frequency in 4 distinct ethnic populations was investigated. The results show that these populations contain predominantly mutually exclusive sets of B*15 alleles.

Sequence of an HLA-B56 variant (B*5604) identified in the Korean population

Three alleles encoding molecules with the B56 serologic specificity have been reported thus far. This study characterized an additional allele encoding a B56 molecule from two unrelated Korean individuals. The novel allele, B*5604, differs from B*5602 by a single nucleotide substitution at codon 103 (CTG-->GTG) resulting in an amino acid change from leucine to valine. The putative haplotype associated with the novel allele was A2-B*5604-Bw6-Cw7-DRB1*15-DRB5*02-DQA1*01-DQB 1*05.