Polymorphism of HLA class I genes in the Brazilian population from the Northeastern State of Pernambuco corroborates anthropological evidence of its origin

HLA diversity in Brazil

Brazil is the fifth largest country in the world in area and the fifth most populous. The Brazilian voluntary Bone Marrow Donor Registry is the third largest in terms of number of donors in the world, being a valuable source of HLA genetics to characterize the donor population of Brazil as well. The genetic background of the Brazilian population is quite heterogeneous, resulting from 5 centuries of admixture among Native Americans, Europeans and Africans, making the Brazilian population unique in terms of genetic ancestry. The unique characteristics of populations in different Brazilian regions make them an exciting focus for genetic diversity studies. Studies on HLA genetic diversity of Brazilian populations have been conducted since the late 1980s and, in this review, we highlight the main findings from studies carried out in Brazil based on classical HLA. In addition, we calculated the genetic distance from the molecular data of the studies included in this review in order to have a broader view of the HLA diversity in Brazilian populations. We emphasize that characterization of HLA diversity is not only important for transplantation programs, but can shed a light on ancestry, history and other demographic patterns with or without association with autoimmune disease.

HLA-A, HLA-B, and HLA-DRB1 Allele and Haplotype Frequencies in Renal Transplant Candidates in a Population in Southern Brazil

BACKGROUND

Very few studies have examined the diversity of human leukocyte antigens (HLA) in the Brazilian renal transplant candidates.

METHODS

The frequencies of the HLA-A, HLA-B, and HLA-DRB1 alleles, haplotypes and phenotypes were studied in 522 patients with chronic renal failure, renal transplant candidates, registered at the Transplant Centers in north/northwestern Paraná State, southern Brazil. Patients were classified according to the ethnic group (319 whites [Caucasians], 134 mestizos [mixed race descendants of Europeans, Africans, and Amerindians; browns or "pardos"] and 69 blacks). The HLA typing was performed by the polymerase chain reaction sequence-specific oligonucleotide method (PCR-SSO), combined with Luminex technology.

RESULTS

In the analysis of the total samples, 20 HLA-A, 32 HLA-B, and 13 HLA-DRB1 allele groups were identified. The most frequent allele groups for each HLA locus were HLA-A*02 (25.4%), HLA-B*44 (10.9%), and HLA-DRB1*13 (13.9%). The most frequent haplotypes were HLA-A*01-B*08-DRB1*03 (2.3%), A*02-B*44-DRB1*07 (1.2%), and A*03-B*07-DRB1*11 (1.0%). Significant differences (P < 0.05) were observed in the HLA-A*68, B*08, and B*58 allele frequencies among ethnic groups.

CONCLUSIONS

This study provides the first data on the HLA-A, HLA-B, and HLA-DRB1 allele, phenotype and haplotype frequencies of renal transplant candidates in a population in southern Brazil.

Rio Grande do Norte, Brazil, voluntary bone marrow donors registry analysis

Objective: this study aimed to report the allele and haplotype frequencies of volunteer bone marrow donors (VBMD) from the state of Rio Grande do Norte (RN) who were enrolled in the Brazilian Volunteer Bone Marrow Donor Registry (REDOME). Methods: the sample comprised 12,973 VBMD who had their allele and haplotype frequencies calculated by Arlequin 3.5.1.2. A multivariate analysis of the data was obtained through a principal component analysis (PCA) and hierarchical cluster analysis (HCA) performed with SPSS 8.0. Results: the most frequent allelic group was HLA-A*02, followed by -DRB1*13, -DRB1*04, -DRB1*07, -B*44, -B*35, -A*24 and -DRB1*01. Of the 2,701 haplotypes observed, the three most frequent were HLA-A*01 B*08 DRB1*03 (1.62%), -A*29 B*44 DRB1*07 (1.56%) and -A*02 B*44 DRB1*04 (1.29%). These haplotypes were in linkage disequilibrium. RN allele and haplotype frequencies were very similar to those in other Brazilian states in which similar studies have been performed. The PCA revealed that RN is highly genetically similar to Caucasian populations, especially those from Iberian countries, which strongly influenced the state’s ethnic composition. Africans and Amerindians also influenced the RN population structure, to a lesser extent. Conclusion: the HCA reinforced the conclusion that, despite its highly admixed profile, the RN population is genetically similar to European and European-descended populations. The PCA also showed that RN cities do not contribute to the same extent to REDOME, with less populous cities being underrepresented, indicating the need to enroll more VBMD from these smaller cities to faithfully depict the state’s population structure in the database.

Frequencies of allele groups HLA-A, HLA-B and HLA-DRB1 in a population from the northwestern region of São Paulo State, Brazil

The aim of this study was to estimate the HLA-A, HLA-B and HLA-DRB1 allele groups frequencies in a population of 1559 volunteer bone marrow donors from the northwestern region of São Paulo State grouped according to ethnicity. An additional objective was to compare the allele frequencies of the current study with data published for other Brazilian populations. The allele groups were characterized by the PCR-rSSO method using Luminex(®) technology. Twenty HLA-A, 32 HLA-B and 13 HLA-DRB1 allele groups were identified. The most common allele groups in European descent and mixed African and European descent samples were HLA-A*02, HLA-B*35 and HLA-DRB1*13, while HLA-A*02, HLA-B*35 and HLA-DRB1*11 were more common in African descent samples. The HLA-A*23, HLA-A*36, HLA-B*58 and HLA-B*81 allele groups were more common in sample from African descent than European descent, and the HLA-DRB1*08 was more common in mixed African and European descent than in European descent. Allele group frequencies were compared with samples from other Brazilian regions. The HLA-A*30 and HLA-A*23 were more common in this study than in the populations of Rio Grande do Sul and Paraná; and the HLA-A*01, HLA-B*18, HLA-B*57 and HLA-DRB1*11 were more common in this study than in the population of Piauí. The least frequent allele groups were HLA-A*31, HLA-B*15, HLA-B*40 and HLA-DRB1*08 for the population of Piauí, HLA-A*01 and HLA-A*11 for Parana, HLA-A*02 and -A*03 for Rio Grande do Sul and HLA-DRB1*04 for Paraná, Rio Grande do Sul and Piauí. These data provide an overview on the knowledge on HLA diversity in the population of the northwestern region of São Paulo State and show that the genes of this system are useful to distinguish different ethnic groups.

Evaluation of the humoral immune response to human leukocyte antigens in Brazilian renal transplant candidates

Pre-transplant sensitization to human leukocyte antigens (HLA) is a risk factor for graft failure. Studies of the immunological profile related to anti-HLA antibodies in Brazilian renal transplant candidates are few. In this study, we evaluated the humoral immune response to HLA antigens in 269 renal transplant candidates, in Paraná State, Brazil. The HLA typing was performed by the polymerase chain reaction sequence-specific oligonucleotide method (PCR-SSO) combined with Luminex technology, using an SSO-LABType commercial kit (One Lambda, Inc., Canoga Park, CA, USA). The percentages of panel-reactive antibodies (PRA) and the specificity of anti-HLA antibodies were determined using the LS1PRA and LS2PRA commercial kits (One Lambda, Inc.). The PRA-positive group consisted of 182 (67.7%) patients, and the PRA-negative group of 87 (32.3%) patients. The two groups differed significantly only with respect to gender. Females were the most sensitized. Among the 182 patients with PRA- positive, 62 (34.1%) were positive for class I and negative for class II, 39 (21.4%) were negative for class I and positive for class II, and 81 (44.5%) were positive for both classes I and II. The HLA-A*02, A*24, A*01, B*44, B*35, B*15, DRB1*11, DRB1*04 and DRB1*03 allele groups were the most frequent. The specificities of anti-HLA antibodies were more frequent: A34, B57, Cw15, Cw16, DR51, DQ8 and DP14. This study documented the profile of anti-HLA antibodies in patients with chronic renal failure who were on waiting lists for an organ in Paraná, and found high sensitization to HLA antigens in the samples.

Polymorphism of leukocyte and erythrocyte antigens in chronic kidney disease patients in southern Brazil

We investigated the polymorphism of human leukocyte antigens (HLA) and Duffy erythrocyte antigens in chronic kidney disease (CKD) patients in southern Brazil. One hundred and eighty-three CKD patients, over 18 years old, on hemodialysis, were included. HLA-A, -B and -DRB1 typing was performed using the LABType®SSO (One Lambda, Inc.). Duffy phenotypes were determined by gel column agglutination using anti-Fy^a and anti-Fy^b monoclonal anti-sera. The patients' predominant ages ranged between 51 and 70 years (43%) and the predominant gender, ethnic group and dialysis period were, respectively, male (62%), white (62%) and 1–3 years (40%). The highest and lowest frequencies of Duffy phenotypes were Fy(a+b+) and Fy(a−b−), respectively. Nineteen HLA-A, 30 HLA-B and 13 HLA-DRB1 allele groups were identified. The most frequent HLA allele groups were HLA-A*01, -A*02, -A*03, -A*11, -A*24; HLA-B*07, -B*15, -B*35, -B*44, -B*51; HLA-DRB1*03, -DRB1*04, -DRB1*07, -DRB1*11 and -DRB1*13. Statistically significant differences were observed in the Duffy and HLA polymorphisms compared between CKD patients and healthy subjects. The Fy(a+b−) phenotype (p<0.0001, OR = 2.56, 95% CI = 1.60–4.07) was the most frequent in the patients (p<0.05), and the Fy(a+b+) phenotype (p = 0.0039, OR = 1.71, 95% CI = 1.18–2.51) was the most frequent in the healthy subjects in the same region of Paraná state (p<0.05). Regarding HLA, the HLA-B*42, -B*45, -B*51 and -DRB1*03 allele groups were the most frequent in the patients (p<0.05), and the HLA-B*44 allele group was the most frequent in the healthy subjects in the same region of Brazil (p<0.05). The polymorphism of these two markers among CKD patients in southern Brazil and healthy subjects of other studies, suggests that these markers might be involved with CKD development. Further studies should be undertaken to analyze the markers' influence on CKD and the long-term results from kidney transplantation.

HLA-A, HLA-B and HLA-DRB1 haplotype frequencies in Piauí's volunteer bone marrow donors enrolled at the Brazilian registry

This study aimed to report the antigen and haplotype frequencies (HFs) of volunteer bone marrow donors (VBMDs) from the state of Piauí who were enrolled in the National Volunteer Bone Marrow Donor Registry (REDOME). The research subjects were 21,943 volunteer bone marrow donors, predominantly young adult women (53.3%). The most frequent allelic group was HLA-A2, followed by -DRB1*13, -DRB1*04, -DRB1*07, -B*15, -B∗35, -B*44, -A*24 and -A*03. Of the 2,704 haplotypes observed, the three most frequent haplotypes were A*29 B*44 DRB1*07 (1.45%), A*01 B*08 DRB1*03 (1.4%) and A*03 B*07 DRB1*15 (0.92%). These three haplotypes were in linkage disequilibrium. PCA showed that 98% of the VBMDs have HLA allele frequencies that are very similar to those from Teresina, the capital city of Piauí. According to the PCA results, these municipalities are distributed with a close proximity to Teresina, which in turn has a close genetic proximity to the Hispanic ethnicity, intermediate proximity to Caucasians and Africans and a distant kinship to Amerindians. The hierarchical proximity of the population of Piauí to the Portuguese and Hispanic populations to shows the strong influence of the latter on the former.

Human leukocyte antigen profiles of latin american populations: differential admixture and its potential impact on hematopoietic stem cell transplantation

The outcome of hematopoietic stem cell transplantation (HSCT) is shaped by both clinical and genetic factors that determine its success. Genetic factors including human leukocyte antigen (HLA) and non-HLA genetic variants are believed to influence the risk of potentially fatal complications after the transplant. Moreover, ethnicity has been proposed as a factor modifying the risk of graft-versus-host disease. The populations of Latin America are a complex array of different admixture processes with varying degrees of ancestral population proportions that came in different migration waves. This complexity makes the study of genetic risks in this region complicated unless the extent of this variation is thoroughly characterized. In this study we compared the HLA-A and HLA-B allele group profiles for 31 Latin American populations and 61 ancestral populations from Iberia, Italy, Sub-Saharan Africa, and America. Results from population genetics comparisons show a wide variation in the HLA profiles from the Latin American populations that correlate with different admixture proportions. Populations in Latin America seem to be organized in at least three groups with (1) strong Amerindian admixture, (2) strong Caucasian component, and (3) a Caucasian-African gradient. These results imply that genetic risk assessment for HSCT in Latin America has to be adapted for different population subgroups rather than as a pan-Hispanic/Latino analysis.

HLA-A, B and DRB1 allele and haplotype frequencies in volunteer bone marrow donors from the north of Parana State

Background

Knowledge of allele and haplotype frequencies of the human leukocyte antigen (HLA) system is important in the search for unrelated bone marrow donors. The Brazilian population is very heterogeneous and the HLA system is highly informative of populations because of the high level of polymorphisms.

Aim

The aim of this study was to characterize the immunogenetic profile of ethnic groups (Caucasians, Afro-Brazilians and Asians) in the north of Parana State.

Methods

A study was carried out of 3978 voluntary bone marrow donors registered in the Brazilian National Bone Marrow Donor Registry and typed for the HLA-A, B and DRB1 (low resolution) loci. The alleles were characterized by the polymerase chain reaction sequence-specific oligonucleotides method using the LabType SSO kit (One Lambda, CA, USA). The ARLEQUIN v.3.11 computer program was used to calculate allele and haplotype frequencies

Results

The most common alleles found in Caucasians were HLA-A*02, 24, 01; HLA-B*35, 44, 51; DRB1*11, 13, 07; for Afro-Brazilians they were HLA-A*02, 03, 30; HLA-B*35, 15, 44; DRB1*13, 11, 03; and for Asians they were: HLA-A*24, 02, 26; HLA-B*40, 51, 52; DRB1*04, 15, 09. The most common haplotype combinations were: HLA-A*01, B*08, DRB1*03 and HLA-A*29, B*44, DRB1*07 for Caucasians; HLA-A*29, B*44, DRB1*07 and HLA-A*01, B*08 and DRB1*03 for Afro-Brazilians; and HLA-A*24, B*52, DRB1*15 and HLA-A*24, B*40 and DRB1*09 for Asians.

Conclusion

There is a need to target and expand bone marrow donor campaigns in the north of Parana State. The data of this study may be used as a reference by the Instituto Nacional de Cancer/Brazilian National Bone Marrow Donor Registry to evaluate the immunogenetic profile of populations in specific regions and in the selection of bone marrow donors

HLA-A, -B, and -DRB1 allelic and haplotypic diversity in a sample of bone marrow volunteer donors from Rio Grande do Sul State, Brazil

The HLA A, B, and DRB1 allele, phenotype, and haplotype frequencies were studied in a sample of 5,000 volunteer bone marrow donors registered at the Brazilian Volunteer Bone Marrow Donor Registry. The participants live in the state of Rio Grande do Sul and were classified according to ethnic group (4,428 Caucasians, 324 mestizos [mixed race], and 248 blacks). Typing was performed using the polymerase chain reaction sequence-specific oligonucleotide method combined with Luminex technology. Twenty-one HLA-A, 33 HLA-B, and 13 HLA-DRB1 allele groups were identified. The most frequent allele groups for each locus were A*02, B*35, and DRB1*13. The most frequent haplotypes were A*01 B*08 DRB1*03 in Caucasians and mestizos and A*02 B*15 and DRB1*04 in blacks. The allele frequencies were compared with samples from different Brazilian regions. In most comparisons no significant differences were found. The most significant differences were observed in the comparison of the groups of our sample, indicating that human leukocyte antigen (HLA) is a good marker to distinguish among people from different ethnic groups. The data provide insight on the knowledge of HLA diversity in the population of Rio Grande do Sul and in the search for a better match for transplant.

Frequency distribution of HLA DQ2 and DQ8 in celiac patients and first-degree relatives in Recife, northeastern Brazil

AIMS

The aim of this study was to evaluate the frequencies of the HLA genotypes DQ2 and DQ8 and the alleles A1*05, A1*0201, B1*0201 and B1*0302 in individuals with celiac disease in Recife, northeastern Brazil.

METHODS

HLA DQ2 and DQ8 genotyping was performed for 73 individuals with celiac disease and 126 first-degree relatives with negative transglutaminase serology. The alleles DQA1*05, DQA1*0201, DQB1*02 and DQB1*0302 were identified by sequencing using specific primers and the EU-DQ kit from the Eurospital Laboratory, Trieste, Italy and double-checked by the All Set SPP kit (Dynal).

RESULTS

Among the 73 cases, 50 (68.5%) had the genotype DQ2, 13 (17.8%) had DQ8, 5 (6.8%) had DQ2 and DQ8, and 5 did not have any of these genotypes. Among the 5 negative individuals, four had the B1*02 allele and one did not have any of the alleles studied. B1*02 was the most frequent allele in both groups (94% in the patients and 89% in the control relatives).

CONCLUSIONS

In this study, celiac disease was associated with the genotypes DQ2 and DQ8. DQ2 predominated, but the distribution of the frequencies was different from what has been found in European populations and was closer to what has been found in the Americas. The high frequencies of the HLA genotypes DQ2 and DQ8 that were found in first-degree relatives would make it difficult to use these HLA genotypes for routine diagnosis of celiac disease in this group.

Distribution of CCR5 genotypes and HLA Class I B alleles in HIV-1 infected and uninfected injecting drug users from Rio de Janeiro, Brazil

Host genetic factors play an important role in the HIV epidemic dynamics, and have been considered in studies assessing susceptibility/resistance to HIV-1 infection as well as clinical evolution. Class I and Class II HLA alleles have been associated with the heterogeneity of HIV-1 infection susceptibility, as protective or risk factors for HIV-1 transmission. Moreover, a 32-base pair deletion in the HIV-1 CCR5 gene-coding region confers resistance to HIV-1 infection in homozygous individuals for the deleted allele. In this study, DNA samples from HIV-1 infected and uninfected injecting drug users (IDUs) from Rio de Janeiro were PCR amplified to determine CCR5 genotypes based on the presence of the CCR5Delta32 mutation and typed for the HLA-B locus, in an attempt to assess possible associations between these genetic factors and susceptibility/resistance to HIV-1 infection. The distribution of CCR5 genotypes between the two IDU groups did not differ. The homozygous mutant genotype Delta32/Delta32 was not found in this study. Except for HLA-B*45 (4.0% vs. 3.0%; p=0.04) and for B*51 (12.1% vs. 4.4%; p=0.002), no statistically significant differences were made evident when analyzing the frequencies of each HLA-B allele between Caucasian and non-Caucasian IDUs. The most frequent HLA-B alleles were B*15; B*35; B*44 and B*51. Although some differences in the allele frequencies could be observed between the two IDU groups, none of these was statistically significant. Therefore, no putative association between these genetic markers and susceptibility/resistance to HIV-1 infection could be made evident in the present study. So far, the assessment of genetic markers among the IDU population has been restricted to North American, European, and Asian studies and this report represents a pioneer descriptive study of the distribution of CCR5 genotypes and HLA-B alleles in Rio de Janeiro, Brazil.

Association study of CCR5 delta 32 polymorphism among the HLA-DRB1 Caucasian population in Northern Paraná, Brazil

Chemokines are important determinants of early inflammatory response. The CC chemokine receptor 5 (CCR5) delta 32 variant results in a nonfunctional form of the chemokine receptor and has been implicated in a variety of immune-mediated diseases. In the present study, polymerase chain reaction (PCR) for genomic deoxyribonucleic acid (DNA) samples, using specific CCR5 oligonucleotide primers surrounding the breakpoint deletion, detected a 225-basepair (bp) product from the normal CCR5 allele and a 193-bp product from the 32 bp deletion allele. Human leukocyte antigen (HLA) class II (DRB1) typing was performed by PCR-sequence-specific primer (PCR-SSP). The aim of this study was to evaluate the association of HLA-DRB1 and CCR5 genetic polymorphisms. To evaluate the frequency distributions of CCR5 delta 32 polymorphisms in a Brazilian population and their association with allelic distribution of HLA genes, DRB1; a total of 120 Caucasian individuals from northern Paraná, Brazil, were tested. The CCR5/CCR5 genotype was found in 108 individuals (90%) and only one carried the CCR5 delta 32 allele homozygous genotype (0.0238), while 12 (10%) carried the CCR5 delta 32 allele heterozygous genotype. The observed frequency for the CCR5 delta 32 allele was 0.05 in the population studied. The results revealed a CCR5 delta 32 allele occurrence with HLA-DRB1(*)01 and DRB1(*)04 (P<0.05). It is possible that HLA-DRB1(*)01 and DRB1(*)04 alleles could be associated with the delta 32-bp deletion of CCR5.

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.

Human leukocyte antigen allelic groups and haplotypes in a brazilian sample of volunteer donors for bone marrow transplant in Curitiba, Paraná, Brazil

Bone Marrow Transplant (BMT) is a lifesaving procedure for several diseases. Histocompatibility between host and donor is crucial for the success of this therapy. Since human leukocyte antigen (HLA) genes are the most polymorphic in humans, a foreknowledge of their frequencies and a vast register of volunteer donors are important for patients who need an unrelated donor. This research evaluated data from 3500 HLA-typed donors using PCR-SSP (One Lambda ABDRX kits, low/medium resolution). The allele and haplotype frequencies were calculated from the donor HLA typings. Among the total sample we observed that the allelic groups HLA-A*02, -B*35, and -DRB1*11 had frequencies of 0.228, 0.112, and 0.125, respectively. The haplotype HLA-A*01-B*08-DRB1*03 was the most frequent (0.024). We also compared our results with another study conducted in a Northeastern Brazilian population. The identification of the most common allelic groups and haplotypes is of great interest, not only to know the HLA composition of the population but also to search for the best HLA match for a transplant. However, the search for the perfect match depends on the eventual registration of every specific donor in the national registers for bone marrow donation.

Typing class I HLA-A gene using a nested PCR-RFLP procedure

In order to detect several new HLA-A class I alleles that have been described since 1998, the original PCR-RFLP method developed to identify the 78 alleles recognized at that time at high resolution level was adapted by us for low and medium resolution levels using a nested PCR-RFLP approach. The results obtained from blood samples of 23 subjects using both the PCR-RFLP method and a commercial kit (MicroSSP1A, One Lambda Inc.) showed an agreement higher than 95%. The PCR-RFLP adapted method was effective in low and medium resolution histocompatibility evaluations.