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

Assessment of mimicking by EBV-CMV immunoglobulin M of anti-HLA antibodies

OBJECTIVE

We aimed to show the cross-reactivity that may occur between immunoglobulin (Ig) M antibodies that form against Cytomegalovirus (CMV) and/or Epstein-Barr virus (EBV) and human leukocyte antigens (HLA).

METHODS

Complement-dependent cytotoxicity (CDC) cross-reactivity between serum samples of 57 patients with IgM positive CMV and/or EBV infections and T and B cells from 15 healthy donors were evaluated. Dithiothreitol was used to distinguish cross-reactivity caused by IgM antibodies from IgG.

RESULTS

The cross-reactivity ratio between pathogenic IgM antibodies with T cell of the 12th donor, and B cell of the 3rd, 4th, and 8th donors was significantly higher (p = 0.011, <0.001, <0.001 and 0.013, respectively). The ratio of B cell CDC cross-reactivity of all donors (26.4%) was higher than the ratio of T cell CDC cross-reactivity (5.2%) (p < 0.001). The ratio of T cell CDC cross-reactivity of sera containing both anti-CMV IgM and anti-EBV IgM antibodies was significantly higher than those of sera containing only anti-CMV IgM or only anti-EBV IgM antibodies (p = 0.002 and p < 0.001, respectively). There was no difference between B cell CDC cross-reactivity rates according to the presence of anti-CMV and/or anti-EBV IgM antibodies.

CONCLUSION

Cross-reactivity may occur between anti-CMV and anti-EBV IgM antibodies with HLA molecules. Thus, in graft recipients, pathogenic IgMs can also act as de novo anti-HLA antibodies and aggravate the rejection process.

A Novel Finding of an HLA Allele's and a Haplotype's Relationship with SARS-CoV-2 Vaccine-Associated Subacute Thyroiditis

Subacute thyroiditis (SAT) is a thyroid disease associated with viral infections. Its relationship with major histocompatibility complex (MHC) antigens was shown before. SAT cases triggered by different types of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have been reported. In this study, human leukocyte antigen (HLA) genotypes of 27 SAT patients (13 vaccine-associated (V-SAT) and 14 non-SARS-CoV-2-infection non-vaccine-associated (non-V-SAT)) were compared with those of 362 healthy donors. HLA analyses were performed with low-resolution DNA-based sequence-specific oligonucleotide or sequence-specific primer methods. Statistical analyses were performed using IBM SPSS Statistics 25 and Stata/MP 14.1 with the hapipf function. Allele and haplotype frequencies were estimated by PyPop and gene[RATE] tool programs. The allele frequencies of HLA-A*11, HLA-B*35, and HLA-C*04 were higher in the patient groups. Both the allele frequency of HLA-A*11 and the haplotype frequency of A*11-B*35-C*04 were higher in the V-SAT group. The A*11-B*35-C*04 haplotype, including all three loci of MHC class I genes, is shown to be associated with the disease for the first time, especially in the V-SAT group. This finding will contribute to a better understanding of the etiopathogenesis of vaccine-associated SAT and the role of HLA genotypes in the functioning mechanisms of the SARS-CoV-2 vaccines.

Frequency of HLA Class I and Class II Alleles in Patients with CVID from Turkey

BACKGROUND

Common variable immunodeficiency (CVID) is the most common symptomatic primary immunodeficiency. Certain gene loci are pointed out in several studies in CVID patients. Until now, monogenic defects have been identified in only 2-10% of CVID patients; therefore, association of the disease with HLA alleles may be important for elucidating immunological and genetic mechanisms behind CVID. The aim of this study is to investigate the relationship between CVID and HLA alleles.

METHODS

HLA class I/II alleles were analyzed in 65 patients with CVID and alleles that may be related to disease susceptibility were determined by comparing with 300 healthy controls. We also evaluated HLA allele frequencies in CVID patients with gastrointestial system (GIS) involvement and autoimmune manifestations.

RESULTS

When compared with controls, frequencies of B*27, B*35, C*04, and DRB1*04 alleles were significantly different in patients with CVID (p < .05). Frequencies of C*12, DRB1*13, and DRB1*15 alleles were more frequent in controls, indicating protective alleles (p < .05). There was a statistically significant difference for DQ2 and DQ8 haplotypes between patients with GIS involvement and controls.

CONCLUSION

In comparison with literature, distinctive HLA alleles found in our study may originate from the diversity in gene pool between the populations. These data may provide clues for disease susceptibility.

HLA-A, -B, -C and -DRB1 allele and haplotype frequencies in the Macedonian population based on a family study

AIM

The aim of this study was to determine HLA allele and 2-, 3- and 4-loci haplotype frequencies in a sample from Macedonian population with defined haplotypes based on family history.

MATERIAL AND METHODS

We analysed 286 unrelated individuals with Macedonian origin, parents of patients who needed stem cell transplantation, in the period of 01.01.2003 till 31.12.2016. Allele and haplotype frequencies, as well as Hardy-Weinberg equilibrium were calculated using the Arlequin3.5 software. Population comparison was calculated using the PHYLIP software.

RESULTS

We identified 18 HLA-A, 26 HLA-B, 13 HLA-C and 13 HLA-DRB1 allele group families. The most frequent allele groups in our population were HLA-A*02 (29.0%), HLA-A*24 (13.8%), HLA-B*35 (16.1%), HLA-B*51 (14.7%), HLA-B*18 (14.7%), HLA-C*07 (27.9%), HLA-DRB1*11 (25.5%) and HLA-DRB1*16 (14.8%). The most frequent four loci haplotype was HLA-A*01-B*08-C*07-DRB1*03 (2.7%). Our comparison showed that the Macedonian population is closely related to the neighbouring countries in the Balkan Peninsula.

CONCLUSION

This study provides data about the HLA diversity in the Macedonian population, which can be very important in the process of unrelated donor search, and in addition yields control group for future disease association studies in our population.

Prevalence of Rheumatoid Arthritis and Spondyloarthritis in Turkey: A Nationwide Study

Objectives

This study aims to estimate the prevalence of rheumatoid arthritis (RA) and spondyloarthritis (SpA) in Turkey using the same telephone questionnaire developed for screening RA and SpA in France and used in Serbia and Lithuania.

Material and methods

The study was performed in two steps. In step I, the French questionnaire was translated into Turkish and validated through a group of 200 patients (80 males, 120 females; mean age 44.0±13.1 years; range 19 to 75 years) followed up at the rheumatology departments of University Hospitals in Antalya and Ankara. In step II, the validated Turkish questionnaire was administered face-to-face to randomly selected 4,012 subjects (1,670 males, 2,342 females; mean age 41.5±16.8 years; range 16 to 97 years) by trained general practitioners across the country, in 25 prov- inces for case detection. The subjects who were suspected of having RA or SpA in accordance with the questionnaire were invited to the nearest university hospital for rheumatologic examination in order to confirm the diagnosis.

Results

In step II, a total of 25 subjects (2 males, 23 females) were diagnosed as RA. The standardized RA prevalence for the general population of Turkey was calculated as 0.56% (95% confidence interval [CI]; 0.33-0.79), 0.10% (95% CI; -0.05-0.25) for males and 0.89% (95% CI; 0.51-1.27) for females. A total of 18 subjects (3 males, 15 females) were diagnosed as SpA. The standardized SpA prevalence for the general population of Turkey was 0.46% (95% CI; 0.25-0.67), 0.17% (95% CI; -0.03-0.37) for males and 0.65% (95% CI; 0.32-0.98) for females. The prevalence of RA was highest in the Northern region (2.00%) and the prevalence of SpA was highest in the Central region (1.49%).

Conclusion

The prevalences of RA and SpA in Turkey are close to each other and there are significant inter-regional variations in prevalences of both RA and SpA.

HLA Genotypes in Turkish Hematopoietic Cell Recipients and Likelihood of Finding a Matched Donor Through Family Searches

OBJECTIVES

Allogeneic hematopoietic stem cell transplant is a life-saving treatment, but donor numbers in Turkey do not meet the increasing demand for this procedure. Here, our objectives were (1) to assess the frequency of HLA-matched related donors in the Turkish population and (2) to identify the HLA antigens and haplotypes that are most frequent in Turkey.

MATERIALS AND METHODS

The HLA genotypes of 841 consecutive recipients and 3071 family members were retrospectively reviewed.

RESULTS

Matched related donors were identified for 368/841 recipients (44%). Extended family donor searches were performed for 111/181 pediatric recipients (61%), with nonsibling matched related donors found for 23 patients (21%). Matched related donors were found for a significantly higher proportion of pediatric patients (52%) than adult patients (41%) (odds ratio of 2.5; 95% confidence interval, 1.9-4.1; P = .02). The percentage of pediatric versus adult patients with 3 or more siblings was 13% versus 46% (odds ratio of 5.6; 95% confidence interval, 3.6-8.5; P = .001). The most frequent HLA class I antigens at each locus were HLA-A*02 (20.2%), HLA-B*35 (19.5%), and HLA-C*07 (19.8%). The most frequent HLA class II antigens at each locus were HLA-DRB1*11 (21.6%) and HLA-DQB1*03 (40.2%). The most common 3-locus haplotypes were HLA-A*24 B*35 DRB1*11 (F:0.020) and HLA-A*01 B*08 DRB1*03 (F:0.015). When adult and pediatric groups were combined, the most common locus haplotypes were found in 43/345 sibling donors (12%) and in 7/23 nonsibling pediatric donors (30%) (odds ratio of 2.7; 95% confidence interval, 1.2-6.4; P = .02).

CONCLUSIONS

The results indicate that, in Turkey, it can be beneficial to revise donor search algorithms to include an extended family donor search before an unrelated donor search. This type of search can be effective because of the HLA haplotype diversity in Turkey, the frequency of consanguinity, and the country's limited donor pool.

Identification of multiple genetic susceptibility loci in Takayasu arteritis

Takayasu arteritis is a rare inflammatory disease of large arteries. The etiology of Takayasu arteritis remains poorly understood, but genetic contribution to the disease pathogenesis is supported by the genetic association with HLA-B*52. We genotyped ~200,000 genetic variants in two ethnically divergent Takayasu arteritis cohorts from Turkey and North America by using a custom-designed genotyping platform (Immunochip). Additional genetic variants and the classical HLA alleles were imputed and analyzed. We identified and confirmed two independent susceptibility loci within the HLA region (r(2) < 0.2): HLA-B/MICA (rs12524487, OR = 3.29, p = 5.57 × 10(-16)) and HLA-DQB1/HLA-DRB1 (rs113452171, OR = 2.34, p = 3.74 × 10(-9); and rs189754752, OR = 2.47, p = 4.22 × 10(-9)). In addition, we identified and confirmed a genetic association between Takayasu arteritis and the FCGR2A/FCGR3A locus on chromosome 1 (rs10919543, OR = 1.81, p = 5.89 × 10(-12)). The risk allele in this locus results in increased mRNA expression of FCGR2A. We also established the genetic association between IL12B and Takayasu arteritis (rs56167332, OR = 1.54, p = 2.18 × 10(-8)).

The role of human leukocyte antigen tissue groups in hepatitis B virus vaccination in Turkey

BACKGROUND/PURPOSE

Between 5% and 10% of the vaccinated population responds less well to standard vaccination schedules irrespective of hepatitis B virus (HBV) vaccination. This manuscript aims at describing possible correlation of different major histocompatibility complex (MHC) Class-I and MHC Class-II haplotype to anti-HBV humoral responsiveness following HBV vaccination.

MATERIALS AND METHODS

The study was conducted on 944 vaccinated hospital staff members and concentrated on the 38 nonresponders as defined by enzyme-linked immunosorbent assay (ELISA) results. In order to define significance of the different haplotypes from the nonresponders, their frequency was compared to the frequency of the same haplotype in 18 randomly selected responders. Human leukocyte antigen (HLA)-A and HLA-B antigens were typed among total mononuclear cells using a standard two-stage microlymphocytotoxicity test. The typing method of HLA Class-II is based on a technique that involves amplification of the second exon of different HLA Class-II genes by PCR.

RESULTS

Positive correlations were found between four HLA-DR (HLA-DRB1*04X, DRB1*0401X, DRB1*11/13, and DRB1*0401X0201) haplotypes and nonresponders but there was a negative correlation with one Class-I (HLA-B13).

CONCLUSION

This study suggested that certain HLA types are associated with nonresponsiveness to vaccination. The different HLA of ethnic groups should also be kept in mind when evaluating the response to hepatitis vaccination. The different HLA gene frequencies of ethnic groups should be examined in further large-scale population-based studies.

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.

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.

Impact of a functional KIR2DS4 allele on heterosexual HIV-1 transmission among discordant Zambian couples

Killer cell immunoglobulin-like receptors (KIRs) and their HLA ligands interact to regulate natural killer (NK) cell function. KIR gene content and allelic variations are reported to influence human immunodeficiency virus (HIV)-1 infection and pathogenesis. We investigated the impact of KIR genes on heterosexual HIV-1 transmission among 566 discordant couples from Lusaka, Zambia. KIR2DS4*001, the only allele of KIR2DS4 known to encode a functional activating receptor, was associated with relatively high viral load for HIV-1 in index (HIV-1 seroprevalent) partners (β [standard error (SE)], .17 [.8] log₁₀; P = .04) and with accelerated transmission of HIV-1 to cohabiting seronegative partners (relative hazard [RH], 2.00; P = .004). The latter association was independent of the direction of transmission (male-to-female or female-to-male), genital ulcers, and carriage of the putative ligand (HLA-Cw*04). No KIR-gene variant in the initially seronegative partners was associated with HIV-1 acquisition or early viral load following seroconversion. Further analysis of NK cell function should clarify the role of KIR2DS4*001 in HIV-1 transmission.

Relationship between HLA tissue type, CMV infection, and acute graft-vs-host disease after allogeneic hematopoietic stem cell transplantation: single-center experience

After allogeneic hematopoietic stem cell transplantation, risk factors for cytomegalovirus (CMV) reactivation include pretransplantation donor and recipient CMV serologic status and posttransplantation development of acute graft-vs-host disease (aGvHD). Human leukocyte antigen (HLA) allele type is an additional factor in CMV infection. The present study included 108 patients who received an allogeneic stem cell graft from an HLA-identical sibling between 1993 and 2004. All recipients and donors were typed for HLA-A, HLA-B, and HLA-DR alleles using serologic or molecular methods. All recipients received grafts because of a hematologic disease from HLA full-matched donors. In pretransplantation seropositive patients with aGvHD, no significant difference was observed in patients who developed CMV infection compared with those without CMV infection. Seropositive patients without aGvHD but with posttransplantation CMV infection demonstrated a higher incidence of HLA-A30, HLA-B40, and HLA-DRB1*15 compared with those without CMV infection. In conclusion, it seems that certain HLA alleles may have either a protective or predisposing role in CMV reactivation, which might be helpful in estimating the risk of aGvHD and designing individualized therapy.

Anti-HLA antibody profile of Turkish patients with end-stage renal disease

Exposure to human leukocyte antigens (HLA) via blood transfusions, pregnancies, and previous transplantations can result in anti-HLA antibody production. The presence of anti-HLA antibodies in recipient sera before transplantation is an important risk factor. To demonstrate the anti-HLA antibody status of Turkish end-stage renal disease (ESRD) patients, 674 patients (mean age, 40.35 +/- 13.15 years; female/male, 328/346) were enrolled into the study. Anti-HLA antibody screening and identification tests were performed using an enzyme-linked immunosorbent assay (ELISA) method. The panel-reactive antibody (PRA)-negative group consisted of 564 (83.6%) and the PRA-positive group consisted of 110 (17.3%) patients. Of the 110 (17.3%) PRA-positive patients, 43 (6.4%) were class I (+) and class II (-); 19 (2.8%) were class I (-) and class II (+); 48 (7.1%) were both class I and II (+). The most frequent antibodies were directed against the A2 crossreactive group (CREG) and the A10 CREG with less frequent reactions against the B7 CREG, indicating antibodies to both frequent (members of A2 CREG) and relatively rare (members of A10 CREG and B7 CREG antigens). These data also suggested that some antibodies occur at greater than expected frequency because of shared epitopes. Our findings confirmed the significant correlation between female gender, pregnancy, failed graft history, long dialysis duration, and blood transfusions with PRA positivity (P < .05).

Impact of HLA on the underlying primary diseases in Turkish patients with end-stage renal disease

The number of patients with end stage renal disease (ESRD) is increasing faster than the number of renal transplantations performed per year worldwide. Of the primary diseases leading to ESRD, diabetic nephropathy is the leading cause. The purpose of the present study is to investigate the association of HLA with the primary diseases leading to ESRD in Turkish patients. A total of 3230 individuals comprising 587 ESRD patients and 2643 healthy controls were enrolled into the study. Class I HLA-A, -B typing was performed by CDC method, while class II HLA-DRB1 typing was performed by low resolution PCR-SSP. We found a significant negative association between almost all A locus antigens and primary disease groups classified as chronic glomerulonephritis and hypertensive nephrosclerosis (p < 0.05). HLA-B58 and HLA-DRB1*03 significantly correlated with amyloidosis and diabetic nephropathy, respectively. Determination of HLAs as risk factors for primary diseases leading to ESRD might be beneficial in preventing progression to ESRD and recurrence of the primary disease post-transplantation.

Criteria for initiation and evaluation of minority donor programs and application to the example of donors of Turkish descent in Germany

Minority donor programs aim to improve access to unrelated hematopoietic SCT for specific ethnic groups through directed donor recruitment. We have developed criteria for initiation and evaluation of such programs and applied them to the situation of donors of Turkish descent in Germany, as well as a program by DKMS German Bone Marrow Center that targets this group. Criteria for program initiation include the number of accessible minority donors, potential impact on the chances of finding matching donors, and general access to unrelated transplantation for patients of the targeted group. Success criteria comprise number and availability of recruited donors, the effect of these donors on the HLA phenotype distribution of a donor file, and the number of donations resulting from the program. More than 40 000 donors of Turkish descent have been recruited within the analyzed program to date. Recruited minority donors show more favorable demographic characteristics but lower availability rates than do German donors. Although HLA haplotype distributions of Turkish and German donors differ considerably, patients with common Turkish HLA phenotypes should benefit from the German donor pool even without a specific minority program. The analysis of donations from minority donors, however, shows specific benefits for patients with rare HLA phenotypes.

Evaluation of HLA-A, -B, -Cw, and -DRB1 alleles frequency in Turkish patients with nasal polyposis

OBJECTIVE

To evaluate whether there is a relationship between HLA-A, -B, -Cw, and -DRB1 alleles and developing nasal polyposis (NP).

STUDY DESIGN

Data from 66 patients with NP were compared with data from 100 healthy randomly selected controls. Asthma, ASA (acetylsalicylic acid) triad, polyp score, and previous sinonasal surgery were also recorded.

SUBJECTS AND METHODS

Genotyping of the HLA-A, -B, -Cw, and -DRB1 alleles were performed with polymerase chain reaction (PCR) with the sequence-specific primer (SSP) method. Data were analyzed by using a Pearson chi(2) test.

RESULTS

The HLA-B*07 and -Cw*12 alleles were found to be significantly higher in the NP patients compared with the control group, whereas the HLA-B*57 and HLA-Cw*04 alleles were significantly lower (P < 0.05). The HLA-A*24, HLA-Cw*12, and HLA-DRB1*04 alleles were determined to be significantly higher in the NP patients with asthma and ASA triad (P < 0.05).

CONCLUSIONS

Our results show that some of the HLA alleles seem to be associated with the genetic susceptibility to develop NP in the Turkish population.

A crypto-Dravidian origin for the nontribal communities of South India based on human leukocyte antigen class I diversity

The Dravidian communities are considered to be the original inhabitants of India, now restricted to South India. The southern most state, Kerala, is socio-culturally stratified into Hindus, Muslims and Christians on the basis of religion. The origin of these religious communities in Kerala is considered to be unique in comparison with that in other parts of the country. These communities were later influenced by the hierarchical caste structure established by the Hindu Brahmins. In the present study, we compared six nontribal (Namboothiri, Nair, Ezhava, Pulaya, Malabar Muslim and Syrian Christian) communities belonging to the major religious groups in Kerala (Hindu, Muslim and Christian) based on the human leukocyte antigen (HLA)-A, -B and -C diversity. Our aim was to understand the genomic substructuring associated with the changing social scenario in various caste and religious groups and compare it with the Dravidian tribal and other world populations. The present study reveals that the HLA diversity of the Dravidian communities is very distinct from that in the other world populations. It is obvious that the nontribal communities of Kerala display a greater Dravidian influence, but traces of genetic admixture with the Mediterranean, western European, central Asian and East Asian populations can be observed. This characterizes the crypto-Dravidian features of the nontribal communities of Kerala. Demic diffusion of the local progressive communities with the migrant communities may have given rise to crypto-Dravidian features among the nontribal communities of Kerala.

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, -B, and -DRB1 polymorphism defined by sequence-based typing of the Han population in Northern China

DNA typing for human leukocyte antigen (HLA)-A, -B and -DRB1 was performed using polymerase chain reaction-sequence-based typing method on 618 randomly selected healthy individuals of the Han population in Northern China. Allele frequencies and haplotypes were statistically analyzed. A total of 84 HLA-A alleles, 143 B alleles, and 122 DRB1 alleles were detected, and 853 A-B-DRB1 haplotypes, 473 A-B haplotypes, and 551 B-DRB1 haplotypes were statistically inferred. Statistical analysis of three-locus haplotypes showed that A*0207-B*4601-DRB1*0901 (3.06%) was the most predominant. Gene frequencies and haplotypic associations within HLA-A, -B, and -DRB1 loci were determined at a high-resolution (four digit) allelic level and should provide useful information in anthropology, bone marrow donor registry, legal medicine, and disease association studies.

HLA-DQ Polymorphism in Turkish Patients With Myasthenia Gravis

Genetic susceptibility to myasthenia gravis (MG) is reported frequently and varies depending on the clinical presentation of the patients. HLA-DQ genotyping was performed in 132 patients using polymerase chain reaction and sequence-specific oligonucleotide hybridizations in the Turkish population for the first time in this study. Antibody positivities against acetylcholine receptor and titin were 81 and 27%, respectively. Sixty-five percent of the patients had disease onset before 40 years of age (EOMG). Overall distribution of DQA1*0103 (odds ratio (OR): 0.5) and DQB1*0502 (OR: 1.9) alleles was different in patients and an ethnically matched healthy control group. Among the subgroups, DQB1*02 was significantly more frequent in EOMG (OR: 1.8), in women with MG (OR: 2.4), and in women with EOMG (OR: 2.8), whereas DQA1*0102 and DQB1*502 (OR: 2.3 for both) were increased and DQA1*0103 (OR: 0.04) was decreased in men with MG. Seropositivity was associated with both DQA1*03 (OR: 12.1) and DQB1*0302 (OR: 14.2) in the patient group. DQA1*02 (OR: 4.9) was associated with the presence of anti-titin antibodies, whereas DQA1*0101 (OR: 3.7) and *0102 (OR: 2.9) were more frequent in patients without this antibody. The presence of thymoma in MG was positively associated with DQB1*0301 (OR: 2.8), and DQB1*02 (OR: 0.3) was significantly less frequent in this group. The HLA-DQ associations in subgroups of MG suggest that the heterogeneity of the disease may be influenced by different genes or even by different alleles. DQ alleles have proved to be relatively informative polymorphisms in studying MG.

Distribution of common CARD15 variants in patients with sporadic Crohn's disease: cases from Turkey

Three common genetic variations, namely, R702W, G908R, and 1007fs, on CARD15 have been shown to increase the risk for Crohn's disease (CD) in Caucasian populations. In this study the frequencies of these CARD15 variants were determined by genotyping in 56 patients with CD and 100 healthy ethnically matched controls from Turkey. Overall frequency of all three variants was 10.7% in CD patients, compared with 1.5% in controls (odds ratio [OR]: 7.9). Among them, the frequency of the G908R variant allele was 8% in CD cases, compared with 0% in controls (OR: 36.8). The allele frequencies of three CD-related CARD15 variants were considerably lower in the control group compared to the reported Caucasian populations. Among the described CARD15 variants, G908R confers an increased susceptibility to CD, whereas the more frequently reported associations in Europeans with R702W and 1007fs are not confirmed in this Turkish population.

HLA class I and II polymorphisms in Azores show different settlements in Oriental and Central islands

Human leucocyte antigen-A, -B, -Cw, -DRB1, -DQA1 and -DQB1 polymorphisms were examined in the Azorean population. The data were obtained at high-resolution level, using polymerase chain reaction (PCR) with sequence-specific primer, PCR-sequence-specific oligonucleotides and sequence-based typing. The most frequent allele in each locus was: A*0201 (24.5%), B*510101 (9.8%), Cw*0401 (14.8%), DRB1*070101 (18.3%), DQA1*0201 (17.4%) and DQB1*0301 (19.4%). The predominant extended haplotype was A*0202-B*1503-Cw*0202-DRB1*090102-DQA1*0303- DQB1*0202 (1.9%), which was found to be absent in the Portuguese mainland. The present study corroborates historical sources that say the Azores were populated not only by Portuguese but also by other Europeans, mostly Flemish people. Despite dendrogram analysis showing some remote Asian genetic affinities, the lack of specific alleles and haplotypes from those populations does not allow us to conclude for direct influence. Haplotype and allele frequencies in Azores show no homogeneous distribution between Oriental and Central islands of this archipelago. The Oriental islands harbour several haplotypes already found in mainland Portugal and identified as Mediterranean and European. The Central group of islands on the contrary clearly shows an influence of north Europeans (most probably derived from a well-documented Flemish settlement), with much less affinity to mainland Portugal.

Taq-I polymorphism in 3'UTR of the IL-12B and association with IL-12p40 production from human PBMC

A wide array of studies has demonstrated differences in genotype and allele frequencies of cytokine gene polymorphisms depending on ethnicity and race. In this study, the frequency of Taq-I polymorphism in 3' untranslated region of IL-12B was investigated in two Bulgarian ethnic groups-Bulgarians and Turkish minority. No significant differences of genotype and allele frequencies were observed between these groups. Genotype distribution in the total group of Bulgarian citizens was: AA (61%), CA (32%) and CC (7%), and the allele frequency of 16974 A allele was 0.77. We also evaluated whether this polymorphism affects IL-12p40 production from human PBMC after stimulation. We demonstrated that association between genotype and IL-12p40 production by stimulated PBMC depends on the stimuli used. Our results indicated a significantly decreased IL-12 p40 secretion for the following order of genotypes: AA>CA>CC, after stimulation of PBMC with C3-binding glycoprotein (C3bgp) in contrast to lipopolysaccharide, phytohaemagglutinin and pokeweed mitogen.

[Human leukocyte antigens A and B in Turkish patients with sarcoidosis]

OBJECTIVE

Associations between human leukocyte antigens (HLA) and sarcoidosis have been reported in several studies. We aimed to investigate these associations in Turkish patients.

PATIENTS AND METHOD

We performed HLA-A, HLA-B, HLA-C, and HLA-D typing in 83 patients with sarcoidosis and in 250 healthy controls using a microlymphocytotoxicity method to investigate genetic susceptibility to the disease.

RESULTS

Because of significant violation of Hardy-Weinberg equilibrium at HLA-C and HLA-DQB1 loci, only results obtained at other HLA loci were used. Although HLA-A9, HLA-B5, and HLA-B8 allele frequencies were significantly higher in the patient group compared to the controls (odds ratio [OR]= 21.8, P= .015; OR= 9.34, P= .049; OR= 2.26, P= .031, respectively), none of the differences remained significant after applying the Bonferroni correction. HLA-A24, HLA-A26, and HLA-B62 alleles were significantly less frequent in the patient group compared to the controls (OR= 0.48, P= .018; OR= 0.19, P= .003; OR= 0.11, P= .044, respectively). However, the differences also failed to remain significant after Bonferroni correction.

CONCLUSIONS

These results suggest that both HLA may play significant roles (either increasing or reducing risk) in the pathogenesis of sarcoidosis and in its distinct clinical forms and laboratory findings.