Distributions of HLA class I alleles and haplotypes in Bulgarians--contribution to understanding the origin of the population

Role of the IL-6 gene in the etiopathogenesis of idiopathic scoliosis

Scoliotic human nuclei pulposi can respond to exogenous proinflammatory stimuli by secreting increased amounts of interleukin-6 (IL-6). The G/C polymorphism of the promoter region of IL-6 gene influences levels and functional activity of the IL-6 protein. We conducted a case-control study of eighty patients with idiopathic scoliosis (IS) and one hundred sixty healthy unrelated gender-matched controls trying to investigate the association between IS and the IL-6 promoter polymorphism at -174 position (rs1800795 G/C) in Bulgarian population. Molecular detection of the IL-6 genotypes was performed by amplification followed by restriction technology. The statistical analysis was performed by Pearson's chi-squared test. Our case-control study revealed a statistically significant association between the IL-6 (-174 G/C) functional polymorphism and susceptibility to IS. In addition, a significant association between the IL-6 (-174 G/C) polymorphism and curve severity was detected. IL-6 gene could be considered as susceptibility and modifying factor of idiopathic scoliosis. The identification of molecular markers with diagnostic and prognostic value could be useful for early detection of children at risk for the development of scoliosis and for prognosis of the risk for a rapid deformity progression. That would facilitate the therapy decisions and early stage treatment of the patient with the least invasive procedures.

HLA gene and haplotype frequencies in Russians, Bashkirs and Tatars, living in the Chelyabinsk Region (Russian South Urals)

We have characterized the HLA-A, -B, -DRB1, -DQA1 and -DQB1 profiles of three major ethnic groups living in Chelyabinsk Region of Russian South Urals, viz., Russians (n = 207), Bashkirs (n = 146) and Tatars (n = 135). First field level typing was performed by PCR using sequence-specific primers. Estimates included carriage and gene frequencies, linkage disequilibrium and its significance and related values. Population comparisons were made between the allele family frequencies of the three populations and between these populations and 20 others using a dendrogram. Chelyabinsk Region Russians demonstrate all the features typical of a Caucasoid population, but also have some peculiarities. Together with Tatars, Russians have high frequencies of allele families and haplotypes characteristic of Finno-Ugric populations. This presupposes a Finno-Ugric impact on Russian and Tatar ethnogenesis. However, this was not apparent in Bashkirs, the first of the three populations to live in this territory, and implies admixture with populations of a Finno-Ugric origin with precursors of Russians and Tatars before they came to the South Urals. The Bashkirs appear close to Mongoloids in allele and haplotype distribution. However, Bashkirs cannot be labelled either as typical Mongoloids or as Caucasoids. Thus, Bashkirs possess some alleles and haplotypes frequent in Mongoloids, which supports the Turkic impact on Bashkir ethnogenesis, but also possess the AH 8.1 haplotype, which could evidence an ancient Caucasoid population that took part in their ethnic formation or of recent admixture with adjacent populations (Russians and Tatars). Bashkirs showed no features of populations with a substantial Finno-Ugric component, for example Chuvashes or Russian Saami. This disputes the commonly held belief of a Finno-Ugric origin for Bashkirs. Tatars appeared close to many European populations. However, they possessed some characteristics of Asiatic populations possibly reflecting a Mongoloid influence on Tatar ethnogenesis. Some aspects of HLA in Tatars appeared close to Chuvashes and Bulgarians, thus supporting the view that Tatars may be descendents of ancient Bulgars.

HLA-A, HLA-B, and HLA-DRB1 allele distribution in a large Armenian population sample

Human leukocyte antigen (HLA)-A, HLA-B, and HLA-DRB1 gene frequencies were investigated in 4279 unrelated Armenian bone marrow donors. HLA alleles were defined by using PCR amplification with sequence specific primers (PCR-SSP) high- and low-resolution kits. The aim of this study was to examine the HLA diversity at the high-resolution level in a large Armenian population sample, and to compare HLA allele group distribution in Armenian subpopulations. The most frequently observed alleles in the HLA class I were HLA-A*0201, A*0101, A*2402, A*0301, HLA-B*5101, HLA-B*3501, and B*4901. Among DRB1 alleles, high frequencies of DRB1*1104 and DRB1*1501 were observed, followed by DRB1*1101 and DRB1*1401. The most common three-locus haplotype found in the Armenian population was A*33-B*14-DRB1*01, followed by A*03-B*35-DRB1*01. Our results show a similar distribution of alleles in Armenian subpopulations from different countries, and from different regions of the Republics of Armenia and Karabagh. The low level of genetic distances between subpopulations indicates a high level of population homogeneity, and the genetic distances between Armenians and other populations show Armenians as a distinct ethnic group relative to others, reflecting the fact that Armenians have been an 'isolated population' throughout centuries. This study is the first comprehensive investigation of HLA-allele group distribution in a subset of Armenian populations, and the first to provide HLA-allele and haplotype frequencies at a high-resolution level. It is a valuable reference for organ transplantation and for future studies of HLA-associated diseases in Armenian populations.

HLA allele and haplotype frequencies in the Albanian population and their relationship with the other European populations

Human leucocyte antigen (HLA) alleles are very interesting markers in identifying population relationships. Moreover, their frequency distribution data are important in the implementation of donor-recipient registry programs for transplantation purposes and also in determining the genetic predisposition for many diseases. For these reasons, we studied the HLA class I and II allele and haplotype frequencies in 160 healthy, unrelated Albanian individuals originating from all regions of the country. The HLA genotyping was performed through a 2-digit resolution SSOP method. The data were analysed with Arlequin and Phylip programs. No deviation was found from the Hardy-Weinberg equilibrium. A total of 17 A*, 30 B*, 12 Cw*, 13 DRB1* and 5 DQB1* alleles were identified. The six most frequent HLA-A-B-DRB1 haplotypes were A*02-B*18-DRB1*11 (5.60%), A*02-B*51-DRB1*16 (4.74%), A*01-B*08-DRB1*03 (3.48%), A*24-B*35-DRB1*11 (2.77%), A*02-B*51-DRB1*13 (2.21%), A*24-B*35-DRB1*14 (1.89%). Interestingly, 12 HLA-A-B-Cw-DRB1-DQB1 haplotypes occurred at a frequency >1%. When compared with the other populations, a close relationship was found with North Greek, Bulgarian, Macedonian, Romanian, Turkish, Cretan, Serbian, Croatian and Italian populations. A higher differentiation in allele frequency level was found with Western Europe populations. These data are the first report of HLA allele and haplotype distribution in an Albanian population inside this country. When compared with other populations, their distribution frequencies show close similarities with neighbouring populations of the entire Balkan area.

Bulgarian Bone Marrow Donors Registry--past and future directions

Recently Bulgarian Bone Marrow Donors Registry (BBMDR) has been established and since August 2005 it has been a member of Bone Marrow Donors Worldwide. Currently the number of healthy donors included in the BBMDR is relatively low. All donors included in the BBMDR are typed for HLA-A, -B, -DRB loci. Phylogenetic analysis based on HLA allele frequencies shows that Bulgarians were characterized with closest genetic similarity to Macedonians, Greeks, Romanians, Cretans and Sardinians in comparison to the other European and Mediterranean populations. On the contrary the second largest ethnic minority-the Roma were the closest to the other Roma populations and North Indians. These differences were due to the predominance of alleles and haplotypes that are specific for the Asian and the other Roma populations. These specific genetic profiles in the Bulgarian ethnic minorities justify the need of an adequate representation of minorities in BBMDR. Future directions for BBMDR development are discussed, including an increase of the total number of donors and these for ethnic minorities, as well the enhancement of the level of resolution of the HLA typing for the donors in the registry.

BoLA class I allele diversity and polymorphism in a herd of cattle

Major histocompatibility complex class I genes are among the most polymorphic genes characterized. The high level of polymorphism is essential for generating host immune responses. In humans, three distinct genomic loci encode human leukocyte antigen (HLA) class I genes, allowing individuals to express up to six different HLA class I molecules. In cattle, the number of distinct genomic loci are currently at least six, and the number of different bovine leukocyte antigens (BoLA) class I molecules that are expressed in individual animals are variable. The extent of allele variation within the cattle population is unknown. In this study, the number and variety of BoLA class I sequences expressed by 36 individuals were determined from full-length BoLA class I cDNA clones. Twenty distinct BoLA class I alleles were identified, with only four being previously reported. The number of expressed BoLA class I alleles in individual animals ranged between one and four, with none of the animals having an identical complement of BoLA class I molecules. Variation existed in the number of BoLA class I alleles expressed as well as the composition of expressed alleles, however, several BoLA class I alleles were found in multiple individual animals. Polymorphic amino acid sites were analyzed for positive and negative selection using the ADAPTSITE program. In the antigen recognition sites (ARS), there were eight positions that were predicted to be under positive selection and three positions that were predicted to be under negative selection from 62 positions. In contrast, for non-antigen recognition sites (non-ARS), there were three positions that were predicted to be under positive selection and 20 that were predicted to be under negative selection from 278, indicating that positive selection of amino acids occurs at a greater frequency within the antigen recognition sites.

[The probability of finding HLA identical or partially matched unrelated donors in the population of Vojvodina]

INTRODUCTION

Allogeneic bone marrow transplantation and hematopoietic stem cell transplantation from unrelated donors are treatments of choice for patients lacking HLA identical siblings or family matched donors.

MATERIAL AND METHODS

Class I HLA typing was performed by using a standard microlymphocytotoxicity test in 434 unrelated persons from Vojvodina, while, class II HLA typing was performed using a modified immunofluorescent technique. The estimated gene frequencies for the populations of Crete, Korea, China, Scotland, Romania, and North America, were used to calculate phenotype frequencies, the probability of finding HLA identical or partially (in 5/6 HLA antigens) matched unrelated donors, the number of donors necessary for research, as well as genetic distances between populations.

RESULTS

The probability of finding HLA identical or partially matched unrelated donors for patients from Vojvodina is higher in closely related populations with low genetic distances, such as populations of Crete, Romania and Scotland.

DISCUSSION

The probability of finding HLA identical or partially matched unrelated donors is in inverse proportion with the number of unrelated donors necessary for research with aim of finding at least one HLA compatible donor.

CONCLUSION

The probability of finding compatible unrelated donors depends on the degree of HLA matching between the donor and recipient, HLA phenotype frequencies and the donor pool size. These methodology may have a wider usage, because it can be applied in calculating the probability of finding suitable genotypically matched donors, by using HLA allele frequencies defined by molecular techniques.

HLA-C molecular characterization of a Lebanese population and genetic structure of 39 populations from Europe to India-Pakistan

Lebanon is located at a continental crossroad between Europe, Africa, and Asia. This region has been the center of wide-scale movements of populations as well as the theater of genetic and cultural trade off among neighboring populations. In this study, HLA-C alleles were characterized by a PCR-SSOP (sequence-specific oligonucleotide probes) hybridization protocol in a sample of 97 Lebanese. A total of 23 alleles were identified with four predominant, Cw*0401, Cw*0602, Cw*0701/06, and Cw*1203, accounting for almost 60% of HLA-C allele frequencies. We included the Lebanese data into a broad analysis of the HLA-C genetic structure of a large set of populations located in Europe, the Middle East, and the Indian subcontinent. Our results indicate that Lebanese exhibit an intermediate genetic profile among the populations from the Middle East, which constitute a rather homogeneous genetic group. In Europe, a high correlation coefficient is found between genetic and geographic distances. In this continent, we also identified a significant genetic frontier following a north-east to south-west axis. This frontier cuts through the Alps and the Pyrenees, thus separating the north-western European populations from those located in the eastern and Mediterranean areas. Finally, the populations from India - Pakistan are very heterogeneous, particularly the Dravidians. Their differentiation has probably been caused by rapid genetic drift under complex influences of cultural, linguistic, and/or religious barriers. Overall, the results show that the HLA-C genetic patterns of these three geographic regions, i.e., the Middle East, Europe, and India-Pakistan, have been shaped by very different genetic histories.

HLA-A and HLA-B allele frequencies in a mestizo population from Guadalajara, Mexico, determined by sequence-based typing

HLA-A and HLA-B genes were typed by DNA sequencing in a mestizo population from Guadalajara, Jalisco, Mexico. Thirty-seven HLA-A and 51 HLA-B alleles were observed in 103 samples. The common typical Amerindian alleles (>5%) and haplotypes (>or=2.0%) found were A*02010101, *24020101, *310102, B*350101, and *4002, and A*310102-B*4002, A*240201-B*350101, and the typical European alleles were A*010101, *29010101, B*1402, B*180101, and A*020101-B*1402, A*020101-B*510101, and A*3002-B*180101. This reflects the blending of the two main parental populations of mestizos: Amerindian and Iberian. Mexicans were found to be relatively closer to the Portuguese than to Spaniards. This proximity may indicate a larger Portuguese influence in Mexicans than previously considered. Present data contribute to the understanding of the genetic structure in Mexico.

Human leukocyte antigen-A, -B and -C alleles and human leukocyte antigen haplotypes in Turkey: relationship to other populations

In this study, we present, for the first time, human leukocyte antigen (HLA) class I allele and haplotype frequencies at the DNA level in a sample of 142 donors from Turkey. HLA typing was performed by medium-to-high resolution polymerase chain reaction sequence-specific oligonucleotide probes method. The most frequent HLA alleles at class I locus were A*0201(0.257), -B*35(0.204) and -Cw*04(0.173). A*0201-B*35-Cw*04(0.056) was the most common three-locus haplotype. Allele and haplotype frequency comparisons and neighbour-joining dendrograms, constructed using DA genetic distances and correspondence analysis using HLA-A, -B and -C, and -DRB1 allele frequencies, revealed similarities with other Mediterranean and European populations, but not with Mongol populations. These results agree with previous studies and confirm that the present day Turkish population is genetically more similar to its geographic neighbours than its historical neighbours in central Asia. The comprehensive HLA data on the Turkish population at the DNA level including up to six-locus putative haplotypes generated in this study will be useful for further studies.

Immunological markers contributing to successful aging in Bulgarians

In order to clarify immunogenetic markers contributing to successful aging, HLA and cytokine gene profiles were analyzed in healthy elderly Bulgarians. Family segregation analysis was performed to define combined effect of haplotypes and immunophenotype profiles. The results of this study did not reveal any statistically significant allele and haplotype frequency differences between elderly and control group. In families with two generations longevity members we did not observed HLA alleles and haplotypes associated with autoimmunity. IL-10 genotype -1082G/A, -819 C/C, -592 C/C, related to the intermediate production, was positively associated, while genotype -1082A/A, -819 C/T, -592 C/A, related to the low level of production, was negatively associated with longevity in Bulgarians. This effect was modulated by IL-6 and IFNgamma genotypes associated with the low level of these pro-inflammatory cytokines. Immunophenotypic studies indicated lower relative and absolute numbers of CD3+8+, CD8+28+ and CD8+57+ cells in elderly people. Analysis in families showed that although most pronounced in the elderly group, lower numbers of CD8+ T cells were also found in middle aged and young members of the families compared to the age matched controls. A progressive CD8+28+ cell subsets decline was seen with aging. In addition, we did not observed the 'immune risk phenotype' which is a marker of an increased inflammatory activity. Based on the results of this study, it seems reasonable to suggest that a combination of specific immunogenetic and immunophenotype profiles could contribute to the successful aging and to maintaining healthy status in elderly.

HLA polymorphism in Bulgarians defined by high-resolution typing methods in comparison with other populations

In the present study we analyzed for the first time HLA class I and class II polymorphisms defined by high-resolution typing methods in the Bulgarian population. Comparisons with other populations of common historical background were performed. Most HLA-A, -B, -DRB alleles and haplotypes observed in the Bulgarian population are also common in Europe. Alleles and haplotypes considered as Mediterranean are relatively frequent in the Bulgarian population. Observation of Oriental alleles confirms the contribution of Asians to the genetic diversity of Bulgarians. The use of high-resolution typing methods allowed to identify allele variants rare for Europeans that were correlated to specific population groups. Phylogenetic and correspondence analyses showed that Bulgarians are more closely related to Macedonians, Greeks, and Romanians than to other European populations and Middle Eastern people living near the Mediterranean. The HLA-A,-B,-DRB1 allele and haplotype diversity defined by high-resolution DNA methods confirm that the Bulgarian population is characterized by features of southern European anthropological type with some influence of additional ethnic groups. Implementation of high-resolution typing methods allows a significantly wider spectrum of HLA variation to be detected, including rare alleles and haplotypes, and further clarifies the origin of Bulgarians.

PCR-SSOP molecular typing of HLA-C alleles in an Iranian population

HLA-C alleles were characterized by a polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) hybridization protocol in a sample of 120 Iranians from Tehran. A total of 23 alleles were identified with the four most predominant--Cw*0401, Cw*0602, Cw*1202, and Cw*0701/06--accounting for almost 50% of HLA-C alleles. A comparison of HLA-C diversity among several populations indicates that Iranians stand at an intermediate genetic position between Europeans and Africans, an observation that may be related to their geographical location at a continental crossroads. The results also reveal a very high correlation between genetic and geographic distances on a global scale. A total of 30 HLA-C-DRB1 haplotypes were found in the Iranians, with the highest frequencies of 6.6% and 6.04 % being for Cw*0602-DRB1*0701 and Cw*1202-DRB1*1502, respectively.