HLA typing in diverse populations (original) (raw)
Related papers
Journal of Clinical & Cellular Immunology
Human Leukocyte Antigen (HLA) encoding genes are part of the major histocompatibility complex (MHC) on human chromosome 6. This region is one of the most polymorphic regions in the human genome. Prior knowledge of HLA allelic polymorphisms is clinically important for matching donor and recipient during organ/tissue transplantation. HLA allelic information is also useful in predicting immune responses to various infectious diseases, genetic disorders and autoimmune conditions. India harbors over a billion people and its population is untapped for HLA allelic diversity. In this study, we explored and compared three HLA typing methods for South Indian population, using Sequence-Specific Primers (SSP), NGS (Roche/454) and single-molecule sequencing (PacBio RS II) platforms. Over 1020 DNA samples were typed at low resolution using SSP method to determine the major HLA alleles within the South Indian population. These studies were followed up with medium resolution HLA typing of 80 samples based on exonic sequences on the Roche/454 sequencing system and high-resolution (6-8 digit) typing of 8 samples for HLA alleles of class I genes (HLA-A, B and C) and class II genes (HLA-DRB1 and DQB1) using PacBio RS II platform. The long reads delivered by SMRT technology, covered the full-length class I and class II genes/alleles in contiguous reads including untranslated regions, exons and introns, which provided phased SNP information. We have identified three novel alleles from PacBio data that were verified by Roche 454 sequencing. This is the first case study of HLA typing using second and third generation NGS technologies for an Indian population. The PacBio platform is a promising platform for large-scale HLA typing for establishing an HLA database for the untapped ethnic populations of India.
Tissue Antigens, 2010
During the 15th International Histocompatibility and Immunogenetics Workshop (IHIWS), 14 human leukocyte antigen (HLA) laboratories participated in the Analysis of HLA Population Data (AHPD) project where 18 new population samples were analyzed statistically and compared with data available from previous workshops. To that aim, an original methodology was developed and used (i) to estimate frequencies by taking into account ambiguous genotypic data, (ii) to test for Hardy–Weinberg equilibrium (HWE) by using a nested likelihood ratio test involving a parameter accounting for HWE deviations, (iii) to test for selective neutrality by using a resampling algorithm, and (iv) to provide explicit graphical representations including allele frequencies and basic statistics for each series of data. A total of 66 data series (1–7 loci per population) were analyzed with this standard approach. Frequency estimates were compliant with HWE in all but one population of mixed stem cell donors. Neutrality testing confirmed the observation of heterozygote excess at all HLA loci, although a significant deviation was established in only a few cases. Population comparisons showed that HLA genetic patterns were mostly shaped by geographic and/or linguistic differentiations in Africa and Europe, but not in America where both genetic drift in isolated populations and gene flow in admixed populations led to a more complex genetic structure. Overall, a fruitful collaboration between HLA typing laboratories and population geneticists allowed finding useful solutions to the problem of estimating gene frequencies and testing basic population diversity statistics on highly complex HLA data (high numbers of alleles and ambiguities), with promising applications in either anthropological, epidemiological, or transplantation studies.
Immunogenetics, 2006
Despite several studies that defined the polymorphism of the nonclassical human leukocyte antigen-E (HLA-E), HLA-F, and HLA-G genes, most polymorphisms thus far examined in correlative studies were derived from the coding sequences of these genes. In addition, some discrepancies and ambiguities in the available data have persisted in current databases. To expand the data available and to resolve some of the discrepant data, we have defined protocols that allow for the amplification of 6 to 7 kb of contiguous genomic sequence for each gene, including all of the coding and intron sequences, approximately 2 kb of 5' flanking promoter sequence, and 1 kb of 3' flanking sequence. Using long-range polymerase chain reaction (PCR) protocols, generating either one or two PCR products depending on the locus, amplified genomic DNA was directly sequenced to completion using a set of about 30 primers over each locus to yield contiguous sequence data from both strands. Using this approach, we sequenced 33 genomic DNAs, from Asian, African American, and Caucasian samples. The results of this analysis confirmed several previously reported coding sequence variants, identified several new allelic variants, and also defined extensive variation in intron and flanking sequences. It was possible to construct haplotype maps and to identify tagging single nucleotide polymorphisms that can be used to detect the composite variation spanning all three genes.
Tissue …, 2010
CITATIONS 5 READS 125 26 authors, including: Some of the authors of this publication are also working on these related projects: Hematological and Solid Tumors: from biomolecular characterization to development of new personalized therapeutic strategies View project Transplantation and oncology: genetic analysis of immunological biomarkers involved in tolerance and tumor pathogenesis. View project Abstract During the 15th International Histocompatibility and Immunogenetics Workshop (IHIWS), 14 human leukocyte antigen (HLA) laboratories participated in the Analysis of HLA Population Data (AHPD) project where 18 new population samples were analyzed statistically and compared with data available from previous workshops.
High-resolution HLA alleles and haplotypes in the United States population
Human Immunology, 2007
We extract and present high-resolution HLA allele and haplotype frequency data available from the National Marrow Donor Program databases from four major U.S. census categories of race and ethnicity. Population-based high-resolution HLA frequencies defined on the basis of from one to five loci are presented and made available online (http:// bioinformatics.nmdp.org/haplotype2006). In addition, a discriminatory classification of HLA allelic variation on the basis of observed population allele frequencies (common, rare and unseen) for HLA A, C, B, DRB1, DQA1, and DQB1 is introduced. The electronic availability of this information will be useful for projects central to the typing and use of population data in HLA applications.
Frontiers in Pharmacology, 2021
The human leukocyte antigen haplotypes HLA-B*15:02 and HLA-A*31:01 have been linked to life-threatening adverse drug reactions to the anticonvulsants carbamazepine and oxcarbazepine. Identification of these haplotypes via pharmacogenetic techniques facilitates implementation of precision medicine to prevent such reactions. Using reference samples from diverse ancestral origins, we investigated the test analytical validity (i.e., ability to detect whether or not the haplotypes were present or absent) of TaqMan assays for single nucleotide variants previously identified as potentially being able to “tag” these haplotypes. A TaqMan custom assay for rs10484555 and an inventoried assay for rs17179220 and were able to identify with 100% sensitivity and 100% specificity HLA-B*15:02 and HLA-A*31:01 respectively. A custom assay for rs144012689 that takes into account a neighboring single nucleotide variant with manual calling was also able to identify HLA-B*15:02 with 100% sensitivity and 10...
Human Immunology, 2002
The high degree of polymorphism of the HLA-system generates a large number of genotypes in different populations. We investigated the degree of genotype diversity that is generated by PCR SSOP IR complying with NMDP standards for HLA-A,-B and DRB loci. We used a set of 43, 62 and 31 probes for HLA-A,-B and DRB1/3/5, respectively. We have analyzed the HLA-A/-B/-DRB1/3/5 unique probe hybridization patterns (UPP) of 20357 unrelated donors representative of all ethnicities in USA. All donors were typed with the same set of reagents and current code nomenclature. We observed a large number of UPP (17379) that are only a small fraction of all possible genotypes (1.80 x 10 ϩ13). In our panel, 85% of the donors showed different unique genotypes. The first 9 frequent genotypes range from 0.39 to 0.025 % and are likely composed by the 8 best known Caucasian haplotypes. Only 15% of the individuals in the panel have a genotype that was present more than once, illustrating the large diversity of the HLA-system and reflects the difficulties to find fully matched unrelated donors. Analysis of cumulative frequencies showed that 3130 UPP are present in 30% of the donors, 7201 UPP in the 50% and 15344 in 90% of the donors studied. In spite of the high number of observed UPP, these only represent 9.5 x 10-8 % of all possible genotypes. This data suggests that it is necessary to span the unrelated donor registries in order to increase the probabilities to find allele level matched donors. Refining the resolution of certain frequent polymorphic segments in different ethnic groups increases the level of resolution and allows to discriminate the mos common alleles of a particular group. Typing of donors with these sets of reagents allows to narrow down the number of potential donors matching a given patient making the selection of higher resolution tests more cost effective and more efficient. The refinement of the HLA-typing strategy will effectively accelerate the donor search process.
16thIHIW: Global distribution of extended HLA haplotypes
International Journal of Immunogenetics, 2013
This report describes the project to identify the global distribution of extended HLA haplotypes, a component of 16th International HLA and Immunogenetics Workshop (IHIW), and summarizes the initial analyses of data collected. The project aims to investigate extended HLA haplotypes, compare their distribution among different populations, assess their frequency in hematopoietic stem cell unrelated donor registries and initiate an international family studies database and DNA repository to be made publicly available. HLA haplotypes compiled in immunogenetics laboratories during the evaluation of transplant candidates and related potential donors were analysed. Haplotypes were determined using the pedigree analysis tool publicly available from the National Marrow Donor Program (NMDP) website. Nineteen laboratories from 10 countries (11 laboratories from North America, five from Asia, two from Latin America and one from Australia) contributed data on a total of 1719 families comprised of 7474 individuals. We identified 10 393 HLA haplotypes, of which 1682 haplotypes included high-resolution typing at HLA-A, B, C, DRB1 and DQB1 loci. We also present haplotypes containing MICA and other HLA loci and haplotypes containing rare alleles seen in these families. The project will be extended through the 17th IHIW, and investigators interested in joining the project may communicate with the first author.