HLA alleles and haplotypes in French North African immigrants

HLA haplotype frequencies and diversity in patients with hemoglobinopathies

The genetic diversity of the human leukocyte antigen (HLA) system was shaped by evolutionary constraints exerted by environmental factors. Analyzing HLA diversity may allow understanding of the underlying pathways and offer useful tools in transplant setting. The aim of this study was to investigate the HLA haplotype diversity in patients with sickle cell disease (SCD, N = 282) or β-thalassemia (β-Thal, N = 60), who received hematopoietic cell transplantation (HCT) reported to Eurocord and the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire (SFGM-TC). We identified 405 different HLA-A-B-DRB1 haplotypes in SCD and 108 in β-Thal patients. Using data from African and European populations of the "1000 Genomes Project" for comparison with SCD and β-Thal, respectively, we found that the haplotypes HLA-A*30-B*14-DRB1*15 (OR 7.87, 95% CI: 1.66-37.3, p b = 0.035), HLA-A*23-B*08 (OR 6.59, 95% CI: 1.8-24.13, p b = 0.023), and HLA-B*14-DRB1*15 (OR 10.74, 95% CI: 3.66-31.57, p b = 0.000) were associated with SCD, and the partial haplotypes HLA-A*30-B*13 and HLA-A*68-B*53 were associated with β-Thal (OR 4.810, 95% CI: 1.55-14.91, p b = 0.033, and OR 17.52, 95% CI: 2.81-184.95, p b = 0.011). Our results confirm the extreme HLA genetic diversity in SCD patients likely due to their African ancestry. This diversity seems less accentuated in patients with β-Thal. Our findings emphasize the need to expand inclusion of donors of African descent in HCT donor registries and cord blood banks.

Diversities of HLA-A, -B, -C, -DRB1 and -DQB1 loci in Chinese Kazak population and its genetic relatedness dissection with multiple populations: a comparative study

Studying the allele and haplotype distributions of human leukocyte antigen (HLA) loci at 2nd-field level in different populations was important. Allele and haplotype frequencies of HLA-A, -B, -C, -DRB1 and -DQB1 loci in 110 unrelated healthy Kazak individuals living in Xinjiang (China) were analyzed using polymerase chain reaction sequence based typing. Thirty HLA-A, 48 HLA-B, 24 HLA-C, 34 HLA-DRB1 and 18 HLA-DQB1 alleles were detected at the 2nd-field level in the Kazak population. Frequencies of HLA alleles, genotypes, and haplotypes were calculated, and some exhibited significantly different distributions among different populations. A neighbor-joining (NJ) tree, heatmap, multidimensional scaling (MDS) and principal component analysis (PCA) were used to explore the genetic relationships between the Kazak population and 32 reference populations distributed in Asia, Africa, America and Europe using frequency data of HLA-A, -B, -C and -DRB1 loci. The NJ tree, heatmap, and MDS of the 33 populations were constructed based on pairwise D_A values of populations obtained by the HLA-A, -B, -C and -DRB1 allele frequencies. Different PCA plots were constructed based on the allele frequencies of HLA-A, -B, -C and -DRB1 or estimated haplotypic frequencies of HLA-A, -B, -C loci. The data obtained in the present research can be used for research on HLA-related diseases or paternity relationships, and aid to finding the best matched donors in stem cell transplantation for Kazak individuals.

Values in tension. Clinical quality and civic participation in umbilical cord blood banking in Italy

In the dominant narrative of bioethics and biomedical discourse on public Umbilical Cord Blood (UCB) banking, the ethical value of donating UCB is unproblematically associated with the clinical quality of collected UCB. This article shows that this view is analytically untenable as it overlooks tensions and conflicts between the social values of donation and the clinical value of banked UCB in concrete arrangements regarding the logistics of UCB donation and collection. Adopting the notion of registers of valuing (Heuts and Mol 2013: Valuation Studies, 1, 2, 125-46) and analysing the case of the Italian network of public UCB banks and collection sites, this article shows how conflicting registers of valuing concerning UCB can shape different organisational models of UCB donation and collection, in which social values and clinical value are not unproblematically conflated. The article aims to demonstrate that the functioning of biobanking arrangements is dependent on how different values are accomplished and aligned in concrete practices of tissue donation and collection.

HLA typing and haematopoietic stem cell transplantation in the histocompatibility unit of the Ibn Sina University Hospital in Rabat (Morocco)

PURPOSE OF STUDY

This study focuses on the search for a suitable related HLA-matched donor of haematopoietic stem cells in the context of allogeneic transplantation in Morocco. The aim of this work is to establish whether the related donor can meet graft needs in Moroccan patients.

PATIENTS AND METHODS

429 families (429 recipients and 965 donors) benefited from HLA typing, using microlymphocytotoxicity, polymerase chain reaction-sequence specific primer and/or high-resolution polymerase chain reaction-specific sequence oligonucleotide.

RESULTS

The recipients and donors are mostly men over 18 years of age. In total, 86.8% of the recipients have between 1 and 3 donors who are 96% of the collaterals. Malignant haemopathies account for 54% of allograft indications. Benign haemopathies are more frequent than malignant in children, whereas the profile is reversed in adults. Fifty percent of recipients have an HLA identical donor in their siblings and 42% and HLA haplo identical donor. The HLA typing of the recipients and the donors reveals very large polymorphism of the population.

CONCLUSION

The related donor of haematopoietic stem cells represents an important source of grafts but will not be able to satisfy all the needs of Morocco. The creation of national unrelated voluntary donors will open up new possibilities for recipients who do not have a compatible donor within his relatives.

Deduced probable human leukocyte antigen haplotypes associated with human leukocyte antigen DRB1*04:36 identified by case analysis of Taiwanese individuals

Objective:

Human leukocyte antigen (HLA) DRB1*04:36 is a low-frequency HLA-DRB1 allele. The aim here is to report the ethnicity of DRB1*04:36 and its associated HLA haplotypes among Taiwanese individuals.

Materials and Methods:

A sequence-based typing method was employed to confirm this low incidence allele. Polymerase chain reaction was performed to amplify exons 2 and 3 of the HLA-A and HLA-B loci and exon 2 of the HLA-DRB1 locus using group-specific primer sets. The amplicons were sequenced in both directions using BigDye Terminator Cycle Sequencing Ready Reaction kits and the manufacturer's protocols. One group of unrelated blood donors used in this study consists of randomized individuals with Taiwanese ethnicity who participate in the Tzu Chi Bone Marrow Donor Registry and the other group are randomized unrelated individuals from mainland China. The family members in the family part of the study are volunteer blood donors.

Results:

In exon 2, the DNA sequence of DRB1*04:36 is identical to DRB1*04:03:01 except for a nucleotide segment from residue 286 to residue 308. The nucleotide segment from residue 286 to residue 308, incidentally, is identical to that of DRB1*11:01:01:01. These observations suggest that DRB1*04:36 may have been derived through a gene recombination event involving DRB1*04:03:01 and DRB1*11:01:01:01. Our family study indicated that the HLA haplotype in association with DRB1*04:36 can be deduced to be A*24:02-B*39:01-DRB1*04:36. A randomized population study using Taiwanese suggests that additional DRB1*04:36 associated HLA haplotypes seem to exist.

Conclusion:

The information on the ethnicity of the DRB1**04:36 allele, and the deduced probable HLA haplotypes associated with the low incidence DRB1*04:36 allele that we report here, is of value to HLA testing laboratories for reference purposes. In addition, they can be used by stem cell transplantation donor search coordinators to aid the creation of strategy for finding compatible donors who are part of unrelated bone marrow donor registries when a patient carries this uncommon HLA allele.

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.

Deduced probable human leukocyte antigen haplotypes associated with HLA-A*11:256Q and HLA-A*02:621 identified by case analyses of Taiwanese individuals

Objective:

HLA-A*11:256Q and HLA-A*02:621 are two low-frequency HLA-A alleles. The aim here is to report the ethnicity of A*11:256Q and A*02:621 and associated human leukocyte antigen (HLA) haplotypes among Taiwanese individuals.

Materials and Methods:

HLA data from randomized Taiwanese registered in the Tzu Chi Stem Cells Centre and China Shanghai Tissuebank Diagnostics were analyzed. HLA typing of the donors was carried out using a sequence-based typing method to confirm the two low-incidence alleles. Polymerase chain reaction was performed to amplify exons 2 and 3 of the HLA-A and HLA-B loci and exon 2 of the HLA-DRB1 locus using group-specific primer sets. The amplicons were sequenced in both directions using BigDye Terminator Cycle Sequencing Ready Reaction kits and the manufacturer's protocols. Exon 1 and exons 4-8 of the A*11:256Q allele were also sequenced and analyzed.

Results:

The Taiwanese ethnicity for both A*11:256Q and A*02:621 alleles was confirmed in this study. Further, the DNA sequence of A* 11:256Q was confirmed to be identical to A*11:02:01from exon 1 to exon 8 except for the residues from 409 to 417 where a segment of nine nucleotides (TACCGGCAG) is deleted in A*11:256Q. The HLA haplotype associated with A*11:256Q was deduced as A*11:256Q-B*27-DRB1*12. In exons 2 and 3, the DNA sequence of A*02:621 is identical to A*02:01:01:01 except at residue 169 where T of A*02:01:01:01 is replaced by C in A*02:621 (at codon 33; TTC->CTC). The HLA haplotype in association with A*02:621 was deduced as A*02:621-B*15:18-DRB1*12:02.

Conclusion:

The information on the ethnicity of the A*11:256Q and A*02:621 alleles and the deduced probable HLA haplotypes associated with the two low-incidence alleles reported here are valuable to HLA testing laboratories for reference purposes. In addition, they can be used by stem cell transplantation donor search coordinators to aid in finding compatible donors in unrelated bone marrow donor registries when a patient carries these uncommon HLA alleles.

Moroccan study of HLA (-A, -B, -C, -DR, -DQ) polymorphism in 647 unrelated controls: Updating data

The scope of this study is to investigate the HLA (Human Leukocyte Antigen) distribution and polymorphism in a large sample of healthy Moroccans in order to extend and update the available data. 647 unrelated Moroccan controls originating from diverse regions of the country were typed using microlymphocytotoxicity for HLA-A and -B, sequence-specific-primer amplification for -C, -DR, and -DQ and Luminex HD for specific -DR. The most frequent allele groups detected were HLA-A2 (19.2%), -B44 (12.4%), -C*07 (24.4%), -DRB1*03 (16.9%), -DRB1*04 (18.4%), -DQB1*02 (28.7%) and -DQB1*03 (27.8%). The most predominant specific alleles found for DRB1 were: *03:01, *04:02, *04:05, *07:01, *11:01, *13:02 and *15:01. Rare allelic variants were detected, for the first time in Moroccan population, at the DRB1*03 (*03:52, *03:54, *03:56), DRB1*07 (*07:07, *07:11, *07:16) and DRB1*11 (*11:70) locus. The most frequent haplotypes were: A2-B44, A30-B18, A2-C*16, A30-C*06, B14-C*08, B58-C*07, B45-C*06, DRB1*03-DQB1*02, DRB1*04-DQB1*03, DRB1*07-DQB1*02 and DRB1*15-DQB1*06. Comparison of genetic distances and haplotypes with other populations shows that the Moroccans are genetically closer to North Africans and Europeans than to sub-Saharan Africans. Our results reflect the high degree of HLA polymorphism in the Moroccan population and provide a useful baseline of healthy Moroccan controls for disease association and anthropological studies.

HLA-A, HLA-B and HLA-DRB1 allele and haplotype diversity among volunteer bone marrow donors from Croatia

The determination of human leucocyte antigen (HLA)-A, HLA-B and HLA-DRB1 alleles in the routine procedure of a volunteer hematopoietic stem cell (HSC) donor's registration in the Croatian Bone Marrow Donor Registry (CBMDR) is performed to enhance the odds of finding a suitable HLA compatible donor for patients in need of a HSC transplantation worldwide. However, besides its original purpose, it also provides valuable information about the HLA polymorphism among Croats. The aim of the present study was to analyse the HLA allele and haplotype frequencies in a sample of 4000 donors from CBMDR. The distribution of HLA-A, HLA-B and HLA-DRB1 alleles did not demonstrate significant differences from the data reported for other European populations. The higher frequency of B*40:02 allele in comparison with B*40:01 and DRB1*11:04 in comparison with DRB1*11:01 is interesting because it represents a difference in comparison with the Western and Northern European populations which are a main source of donors for Croatian patients. The haplotype frequencies show a greater variation and difference in comparison with data from other registries and populations; however, due to a lack of high-resolution haplotype data, comparison was possible only with a very limited number of other populations.

Discovery of the novel HLA-DRB1*10:04 allele in a Taiwanese volunteer bone marrow donor and identification of the probable HLA-A, -B, -C and -DRB1 haplotype in association with DRB1*10:04

We report here a novel variant of HLA-DRB1*10, DRB1*10:04, discovered in a Taiwanese volunteer bone marrow donor by a sequence-based typing (SBT) method. The DNA sequence of DRB1*10:04 differs from DRB1*10:01:01, in exon 2, at nucleotide positions 296 (G fi A) and 303 (T fi G). The nucleotide changes caused an amino acid substitution at amino acid residue 70 (R fi Q). We hypothesize that the formation of DRB1*10:04 was probably the result of a gene recombination event where DRB1*10:01:01 received a minimum length of DNA sequence from DRB1*04:05:01, as the sequence of DRB1*10:04 is identical to DRB1*10:01:01 in exon 2 except the sequence from nucleotide 296 to nucleotide 303, which is identical to DRB1*04:05:01. The plausible HLA-A, -B, -C and - DRB1 haplotypes in association with DRB1*10:04 was deduced as A*01:01-B*37:01-C*06:02-DRB1*10:04.

Analysis of HLA-A, -B, -C, -DR, -DQ polymorphisms in the South Tunisian population and a comparison with other populations

BACKGROUND

The Human Leucocyte Antigen (HLA) system is often used as a genetic marker for analysing populations. HLA antigen distribution among the Tunisian population is not well defined because of the lack of a general population study.

AIM

The aim of the present study was to investigate the polymorphism of HLA-A, -B, -C, -DR and -DQ loci in the South Tunisian population.

SUBJECTS AND METHODS

This study has investigated HLA-A, -B, -C, -DR and -DQ polymorphisms in 123 unrelated healthy individuals originating from the south of Tunisia. HLA class I was studied by serology and completed by polymerase chain reaction-sequence specific primer (PCR-SSP). HLA class II was performed using PCR-SSP.

RESULTS

The most common alleles were A-2 (0.2154), B-44 (0.1179), C7 (0.2114), DR4 (0.1626) and DQ2 (0.313). A1-B-8-C7-DR3-DQ2 (2.84%) was the predominant haplotype in this population. Comparisons with data of other worldwide populations based on phylogenetic tree and multidimensional scaling analysis were done. This study suggests that both HLA class I and class II polymorphism specificities demonstrate a high diversity in this South Tunisian population, which reflects ancient and recent admixture with neighbouring populations.

CONCLUSION

The results provide useful information for further studies of Tunisian population evolution, anthropology and for resolving HLA frequencies when searching for HLA-compatible donors in transplantation and for the analysis of disease associations.

HLA-A, -B and -DRB1 allele frequencies in Cyrenaica population (Libya) and genetic relationships with other populations

The frequencies of HLA-A, HLA-B and HLA-DRB1 alleles in 118 unrelated Libyans from Benghazi (Cyrenaica) were analysed using high resolution typing and compared with other populations. Their relatedness has been tested by correspondence analyses and principal component analysis. The most frequent HLA-A alleles were A(∗)02:01:01:01 (15.7%), A(∗)01:01:01:01 (11.4%) and A(∗)03:01:01:01 (9.3%). For the HLA-B locus, the commonest allele was HLA-B(∗)50:01:01 (14.4%) followed by B(∗)51:01:01 (9.8%) and B(∗)08:01:01 (6.4%). For the HLA-DRB1 locus, the commonest was HLA-DRB1(∗)07:01:01:01 (16.9%) followed by DRB1(∗)03:01:01:01 (13.6%) and DRB1(∗)13:02:01 (9.3%). The most frequent two-locus haplotypes were HLA-A(∗)02:01:01:01-B(∗)07:02:01 (3.0%) and HLA-B(∗)50:01:01-DRB1(∗)07:01:01:01 (9.6%), and three-locus haplotypes were HLA-A(∗)02:01:01:01-B(∗)50:01:01-DRB1(∗)07:01:01:01 (4.2%) and HLA-A(∗)11:01:01-B(∗)52:01:01:01-DRB1(∗)15:02:01 (2.5%). This study is the first on the HLA status of a Libyan population. The results, when compared to similar HLA data obtained previously from African and Mediterranean populations, indicate genetic influences from several ethnic groups. Moreover, the differences in the HLA allele frequencies between the Libyan population and others reveals that significant admixture has occurred between the original Berber inhabitants and neighbouring and more distant populations, even though a strong genetic Berber substratum remains. These data will be of value to future anthropological and disease association studies involving the Libyan population.

Molecular analysis of human leukocyte antigen class I and class II allele frequencies and haplotype distribution in Pakistani population

AIM:

Distribution of HLA class I and II alleles and haplotype was studied in Pakistani population and compared with the data reported for Caucasoid, Africans, Orientals and Arab populations.

MATERIALS AND METHODS:

HLA class I and II polymorphisms in 1000 unrelated Pakistani individuals was studied using sequence-specific primers and polymerase chain reaction and assay.

RESULTS:

The most frequent class I alleles observed were A*02, B*35 and CW*07, with frequencies of 19.2, 13.7 and 20%, respectively. Fifteen distinct HLA-DRB1 alleles and eight HLA-DQB1 alleles were recognized. The most frequently observed DRB1 alleles which represented more than 60% of the subjects were DRB1 *03, *07, *11 and *15. The rare DRB1 alleles detected in this study were HLADRB1 *08 and *09, having frequencies of 0.9 and 1.7%, respectively. In addition, at DRB1-DQB1 loci there were 179 different haplotypes and 285 unique genotypes and the most common haplotype was DRB1*15-DQB1*06 which represented 17% of the total DRB1-DQB1 haplotypes. In our population, haplotype A*33-B*58-Cw*03 comprised 2.8% of the total class I haplotypes observed. This haplotype was seen only in the oriental populations and has not been reported in the African or European Caucasoid.

CONCLUSION:

Our study showed a close similarity of HLA class I and II alleles with that of European Caucasoid and Orientals. In Pakistani population, two rare loci and three haplotypes were identified, whereas haplotypes characteristic of Caucasians, Africans and Orientals were also found, suggesting an admixture of different races due to migration to and from this region.

Characterization of the novel HLA-B allele, B*4621, in a Chinese individual

We report that a novel HLA-B allele, B*4603 has been identified during routine PCR-SSOP typing in a sample from a registered female donor of Chinese Marrow Donor Program.

High-resolution human leukocyte antigen (HLA) haplotypes and linkage disequilibrium of HLA-B and -C and HLA-DRB1 and -DQB1 alleles in a Taiwanese population

Using the maximum-likelihood method with the expectation-maximization (EM) algorithm of PYPOP, high-resolution human leukocyte antigen (HLA) three-locus haplotypes (HLA-A, -B, and -C; HLA-A, -B, and -DRB1) and four-locus haplotypes (HLA-A, -B, -C, and -DRB1) were determined. Linkage disequilibrium of high-resolution HLA-B and -C alleles and HLA-DRB1 and -DQB1 alleles was also calculated. Comparison of the Taiwanese haplotypes and haplotypes from donors in the Chinese Han population, the Asia Pacific Islander ethnic category of the NMDP (National Marrow Donor Program), and the Taiwanese cord blood units demonstrated similarities and dissimilarities among the four populations. HLA allele frequencies of our study suggested that the Taiwanese have a relative population relationship with the southern Han Chinese with regard to HLA. Our results also indicated that the Taiwanese population exhibits genetic proximity with Asian Americans with regard to HLA-A and -DRB1 but not HLA-B.

Balancing selection and heterogeneity across the classical human leukocyte antigen loci: a meta-analytic review of 497 population studies

This paper presents a meta-analysis of high-resolution human leukocyte antigen (HLA) allele frequency data describing 497 population samples. Most of the datasets were compiled from studies published in eight journals from 1990 to 2007; additional datasets came from the International Histocompatibility Workshops and from the AlleleFrequencies.net database. In all, these data represent approximately 66,800 individuals from throughout the world, providing an opportunity to observe trends that may not have been evident at the time the data were originally analyzed, especially with regard to the relative importance of balancing selection among the HLA loci. Population genetic measures of allele frequency distributions were summarized across populations by locus and geographic region. A role for balancing selection maintaining much of HLA variation was confirmed. Further, the breadth of this meta-analysis allowed the ranking of the HLA loci, with DQA1 and HLA-C showing the strongest balancing selection and DPB1 being compatible with neutrality. Comparisons of the allelic spectra reported by studies since 1990 indicate that most of the HLA alleles identified since 2000 are very-low-frequency alleles. The literature-based allele-count data, as well as maps summarizing the geographic distributions for each allele, are available online.

HLA-associated genetic resistance and susceptibility to type I diabetes in French North Africans and French natives

The distribution of human leukocyte antigen (HLA)-DRB1-DQA1-DQB1 haplotypes was analyzed separately in two distinct French ethnic groups with type I diabetes (T1D), i.e. French North African migrants (n= 64, mean age at diagnosis = 8.25 years) and ancient French natives (n= 60, mean age at diagnosis = 7.42 years). HLA associations were determined by calculating odds ratios (ORs) between patients and two ethnic-matched control populations. Results show highly similar ORs for the conservative DRB1*0301-DQA1*0501-DQB1*0201 haplotype of susceptibility (OR: 3.22 and 3.93 in migrants and natives, respectively) and the DRB1*1501-DQA1*0102-DQB1*0602 haplotype of resistance (OR: 0.05 and 0.03, respectively). In contrast, among the more variable DRB1*04-DQB1*0302 haplotypes of susceptibility, the DRB1*0402 (OR: 3.10 and 32.84) and 0405 (OR: 5.90 and 16.25, respectively) were associated with T1D in migrants and natives, whereas an increase of DRB1*0401, a rare allele in migrants, was significant in natives only. Also, among the DRB1*11-DQA1*0505-DQB1*0301 haplotypes of resistance, the OR observed for DRB1*1104-DQA1*0505-DQB1*0301, common in migrants, was lower (OR: 0.08) than for DRB1*1101-DQA1*0505-DQB1*0301 (OR: 0.32), common in natives. How DRB1*11 subtypes might affect differently the risk conferred by DQA1*0505-DQB1*0301 will be discussed.