RESUMEN
The novel HLA-DPB1*14:01:15 allele differs from DPB1*14:01:01:01 by change of C > T in exon 3.
Asunto(s)
Alelos , Secuencia de Bases , Exones , Cadenas beta de HLA-DP , Prueba de Histocompatibilidad , Donantes de Tejidos , Humanos , Cadenas beta de HLA-DP/genética , Brasil , Análisis de Secuencia de ADN/métodos , Médula Ósea , Alineación de Secuencia , Codón , Trasplante de Médula ÓseaRESUMEN
Identification of four new HLA alleles (B*27:265, B*35:569, DRB1*08:117, and DPB1*1435:01) in Brazilian bone marrow donors.
Asunto(s)
Antígenos HLA-B , Humanos , Frecuencia de los Genes , Alelos , Cadenas beta de HLA-DP/genética , Cadenas HLA-DRB1/genética , Antígenos HLA-B/genéticaRESUMEN
The novel HLA-DPB1*04:01:51 allele first described in a potential bone marrow donor from Brazil.
Asunto(s)
Trasplante de Médula Ósea , Médula Ósea , Alelos , Brasil , Cadenas beta de HLA-DP , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Polimorfismo de Nucleótido SimpleRESUMEN
BACKGROUND: HLA molecular mismatch (MM) is a risk factor for de novo donor-specific antibody (dnDSA) development in solid organ transplantation. HLA expression differences have also been associated with adverse outcomes in hematopoietic cell transplantation. We sought to study both MM and expression in assessing dnDSA risk. METHODS: One hundred three HLA-DP-mismatched solid organ transplantation pairs were retrospectively analyzed. MM was computed using amino acids (aa), eplets, and, supplementarily, Grantham/Epstein scores. DPB1 alleles were classified as rs9277534-A (low-expression) or rs9277534-G (high-expression) linked. To determine the associations between risk factors and dnDSA, logistic regression, linkage disequilibrium (LD), and population-based analyses were performed. RESULTS: A high-risk AA:GX (recipient:donor) expression combination (X = A or G) demonstrated strong association with HLA-DP dnDSA (P = 0.001). MM was also associated with HLA-DP dnDSA when evaluated by itself (eplet P = 0.007, aa P = 0.003, Grantham P = 0.005, Epstein P = 0.004). When attempting to determine the relative individual effects of the risk factors in multivariable analysis, only AA:GX expression status retained a strong association (relative risk = 18.6, P = 0.007 with eplet; relative risk = 15.8, P = 0.02 with aa), while MM was no longer significant (eplet P = 0.56, aa P = 0.51). Importantly, these risk factors are correlated, due to LD between the expression-tagging single-nucleotide polymorphism and polymorphisms along HLA-DPB1. CONCLUSIONS: The MM and expression risk factors each appear to be strong predictors of HLA-DP dnDSA and to possess clinical utility; however, these two risk factors are closely correlated. These metrics may represent distinct ways of characterizing a common overlapping dnDSA risk profile, but they are not independent. Further, we demonstrate the importance and detailed implications of LD effects in dnDSA risk assessment and possibly transplantation overall.
Asunto(s)
Rechazo de Injerto/inmunología , Cadenas beta de HLA-DP/biosíntesis , Isoanticuerpos/inmunología , Trasplante de Riñón/efectos adversos , Donantes de Tejidos , Estudios de Seguimiento , Cadenas beta de HLA-DP/inmunología , Trasplante de Células Madre Hematopoyéticas/métodos , Prueba de Histocompatibilidad , Humanos , Desequilibrio de Ligamiento , Estudios RetrospectivosRESUMEN
Despite intense efforts, the number of new cases of leprosy has remained significantly high over the past 20 years. Host genetic background is strongly linked to the pathogenesis of this disease, which is caused by Mycobacterium leprae (M. leprae), and there is a consensus that the most significant genetic association with leprosy is attributed to the major histocompatibility complex (MHC). Here, we investigated the association of human leukocyte antigen (HLA) class I and II genes with leprosy in a Brazilian population encompassing 826 individuals from a hyperendemic area of Brazil; HLA typing of class I (-A, -B, -C) and class II (-DRB1, -DQA1, -DQB1, -DPA1, and -DPB1) loci was conducted. Initially, the associations were tested using the chi-square test, with p-values adjusted using the false discovery rate (FDR) method. Next, statistically significant signals of the associations were submitted to logistic regression analyses to adjust for sex and molecular ancestry data. The results showed that HLA-C*08, -DPB1*04, and -DPB1*18 were associated with protective effects, while HLA-C*12 and -DPB1*105 were associated with susceptibility to leprosy. Thus, our findings reveal new associations between leprosy and the HLA-DPB1 locus and confirm previous associations between the HLA-C locus and leprosy.
Asunto(s)
Predisposición Genética a la Enfermedad , Antígenos HLA-C/genética , Cadenas beta de HLA-DP/genética , Lepra/genética , Adolescente , Adulto , Anciano , Alelos , Brasil/epidemiología , Estudios de Casos y Controles , Enfermedades Endémicas , Femenino , Sitios Genéticos , Antígenos HLA-C/inmunología , Cadenas beta de HLA-DP/inmunología , Humanos , Lepra/epidemiología , Lepra/inmunología , Lepra/microbiología , Masculino , Persona de Mediana Edad , Mycobacterium leprae/inmunología , Adulto JovenRESUMEN
BACKGROUND: The impact of HLA-DPB1 compatibility and its role as a transplantation antigen in haploidentical-related hematopoietic stem cell transplant (haplo-R-HSCT) have not been established, and a negative effect on survival has been suggested. OBJECTIVE: The objective of the determine was to study the frequency and clinical effects of incompatibility at the HLA-DPB1 locus in the haplo-R-HSCT setting. METHODS: Clinical records and electronic files of 91 patients with a hematological disease who underwent haplo-HSCT from January 2009 to October 2017 in a university medical center were scrutinized. Overall survival (OS) was estimated by the Kaplan-Meier method; the cumulative incidence of transplant-related mortality (TRM) and relapse rates was determined. Acute graft-versus-host disease was assessed by binary logistic regression. Cox regression model with a 95% confidence interval was used to examine the association between the different variables and their effect on OS. RESULTS: Of the 91 donor-recipient pairs, 24 (26.37%) shared complete DPB1 identity, 60 (65.93%) had a mismatch at one allele, and 7 (7.70%) were mismatched at two alleles. Twenty-four different HLA-DPB1 alleles were found; the most frequent were DPB1*04:01 (34.1%) and DPB1*04:02 (27.5%). Two-year OS, the cumulative incidence of TRM and relapse was 51.3 ± 6.8%, 28 ± 6% and 60 ± 7.8% for all haplo-related transplants, respectively, with no statistical difference between HLA-DPB1 matched and partially matched patients. In Cox regression analysis, no risk factors associated with OS, TRM, or relapses were identified. CONCLUSION: HLA-DPB1 mismatching in the haplo-R-HSCT setting did not influence transplant outcomes and was clinically tolerable. A high degree of homozygosity was found.
Asunto(s)
Cadenas beta de HLA-DP , Enfermedades Hematológicas/cirugía , Trasplante de Células Madre Hematopoyéticas/métodos , Trasplante Haploidéntico , Adolescente , Adulto , Niño , Preescolar , Selección de Donante , Femenino , Enfermedades Hematológicas/mortalidad , Humanos , Lactante , Masculino , Persona de Mediana Edad , Selección de Paciente , Estudios Retrospectivos , Tasa de Supervivencia , Resultado del Tratamiento , Adulto JovenRESUMEN
ABSTRACT Background: The impact of HLA-DPB1 compatibility and its role as a transplantation antigen in haploidentical-related hematopoietic stem cell transplant (haplo-R-HSCT) have not been established, and a negative effect on survival has been suggested. Objective: The objective of the determine was to study the frequency and clinical effects of incompatibility at the HLA-DPB1 locus in the haplo-R-HSCT setting. Methods: Clinical records and electronic files of 91 patients with a hematological disease who underwent haplo-HSCT from January 2009 to October 2017 in a university medical center were scrutinized. Overall survival (OS) was estimated by the Kaplan-Meier method; the cumulative incidence of transplant-related mortality (TRM) and relapse rates was determined. Acute graft-versus-host disease was assessed by binary logistic regression. Cox regression model with a 95% confidence interval was used to examine the association between the different variables and their effect on OS. Results: Of the 91 donor-recipient pairs, 24 (26.37%) shared complete DPB1 identity, 60 (65.93%) had a mismatch at one allele, and 7 (7.70%) were mismatched at two alleles. Twenty-four different HLA-DPB1 alleles were found; the most frequent were DPB1*04:01 (34.1%) and DPB1*04:02 (27.5%). Two-year OS, the cumulative incidence of TRM and relapse was 51.3 ± 6.8%, 28 ± 6% and 60 ± 7.8% for all haplo-related transplants, respectively, with no statistical difference between HLA-DPB1 matched and partially matched patients. In Cox regression analysis, no risk factors associated with OS, TRM, or relapses were identified. Conclusion: HLA-DPB1 mismatching in the haplo-R-HSCT setting did not influence transplant outcomes and was clinically tolerable. A high degree of homozygosity was found.
Asunto(s)
Humanos , Masculino , Femenino , Lactante , Preescolar , Niño , Adolescente , Adulto , Persona de Mediana Edad , Adulto Joven , Trasplante de Células Madre Hematopoyéticas/métodos , Cadenas beta de HLA-DP , Trasplante Haploidéntico , Enfermedades Hematológicas/cirugía , Tasa de Supervivencia , Estudios Retrospectivos , Resultado del Tratamiento , Selección de Paciente , Selección de Donante , Enfermedades Hematológicas/mortalidadRESUMEN
Hepatitis B virus (HBV) infection is a serious public health problem worldwide. The progression of the disease depends on several host and viral factors and may result in fulminant hepatitis (very rare), acute hepatitis with spontaneous clearance, and chronic hepatitis B infection. Previous studies demonstrated that variations in the human leukocyte antigen (HLA) class II (HLA-DPB1 and HLA-DQB2 genes) are related to the chronic HBV infection. This study aimed to investigate the association of two single nucleotide polymorphism (SNPs), one in the HLA-DPB1 (rs9277535) and one in the HLA-DQB2 (rs7453920), with chronic hepatitis B infection in a southern Brazilian sample. This case-control study included 260 HBV patients attended in a Specialized Center for Health in Caxias do Sul (Brazil) between 2014 and 2016. The same number of controls (matching for age, gender, and ethnicity) was obtained in a University Hospital in the same city and period. Blood samples were collected and genomic DNA was extracted. Genotyping were performed by real-time Taqman PCR method. Odds ratios with 95% confidence intervals and significance level of 5% (P < 0.05) were calculated. Allele frequencies in the SNP rs9277535 were 72.6% for A and 27.4% for G nucleotides in cases and 75.0% for A and 25.0% for G in controls. Allele frequencies in the SNP rs7453920 were of 25.7% for A and 74.3% for G in cases and 28.8% for A and 71.2% for G in controls. No statistically significant association was found between both SNPs and chronic hepatitis B (P > 0.05).
Asunto(s)
Cadenas beta de HLA-DP/genética , Antígenos HLA-DQ/genética , Hepatitis B Crónica/genética , Polimorfismo de Nucleótido Simple , Adulto , Brasil , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
BACKGROUND & AIMS: HBV infection exhibits geographical variation in its distribution in South America. While HBV rates are low in central Argentina, the north-western region exhibits intermediate HBV rates. Unfortunately, the reasons that could explain this difference are still unknown. METHODS: A total of 1440 Argentines were recruited and grouped into HBV patients, HBV-resolved individuals and healthy controls. Genetic ancestry was assessed by analysis of biparental lineages and ancestry autosomal typing. SNPs of HLA-DPA1 (rs3077), HLA-DPB1 (rs9277542), HLA-DQB1 (rs2856718) and HLA-DQB2 (rs7453920) were determined, and HBV genotyping was performed by phylogenetic analysis in HBV patients. RESULTS: Native American ancestry prevailed in the north-western region when compared with central Argentina (P<.0001). However, no differences were observed among the three groups of each region. The distribution of HBV genotypes revealed significant differences (P<.0001). Three SNPs (rs3077, rs9277542 and rs7453920) showed a significant association with protection against chronic HBV and viral clearance in both regions. The remaining SNP showed a significant association with susceptibility to chronic HBV. The frequency rates of rs3077-T, related to protection against chronic HBV and viral clearance, were lower in north-western Argentina when compared with central Argentina. The same uneven frequency rates were observed for SNP rs9277542. CONCLUSIONS: This is the first study addressing the associations between the HLA-DP and HLA-DQ loci and the protection against chronic HBV and viral clearance in a multiethnic South American population. The uneven distribution of HLA-DP and HLA-DQ supports the HBV epidemiological differences observed in these two regions of Argentina with dissimilar ancestry genetic background.
Asunto(s)
Antígenos HLA/genética , Virus de la Hepatitis B/genética , Hepatitis B Crónica/genética , Polimorfismo de Nucleótido Simple , Adulto , Anciano , Argentina/epidemiología , Distribución de Chi-Cuadrado , Femenino , Frecuencia de los Genes , Genotipo , Antígenos HLA/inmunología , Cadenas alfa de HLA-DP/genética , Cadenas alfa de HLA-DP/inmunología , Cadenas beta de HLA-DP/genética , Cadenas beta de HLA-DP/inmunología , Antígenos HLA-DQ/genética , Antígenos HLA-DQ/inmunología , Cadenas beta de HLA-DQ/genética , Cadenas beta de HLA-DQ/inmunología , Virus de la Hepatitis B/inmunología , Hepatitis B Crónica/etnología , Hepatitis B Crónica/inmunología , Hepatitis B Crónica/virología , Interacciones Huésped-Patógeno , Humanos , Desequilibrio de Ligamiento , Modelos Logísticos , Masculino , Persona de Mediana Edad , Epidemiología Molecular , Análisis Multivariante , Oportunidad Relativa , Filogenia , Factores Protectores , Factores de RiesgoRESUMEN
Autoantibodies targeting the H+/K+-ATPase proton pump of the gastric parietal cell (parietal cell antibodies [PCA]) are diagnostic of atrophic body gastritis (ABG) leading to pernicious anemia (PA). PCA, ABG, and PA occur in increased frequency in patients with type 1 diabetes and their relatives and are considered "minor" components of forms of autoimmune polyglandular syndrome (APS). A customized radioimmunoprecipitation assay was applied to 6,749 samples from the Type 1 Diabetes Genetics Consortium to measure ATP4A autoreactivity. Autoantibody prevalence was correlated with variants in HLA class II, PTPN22, and CTLA4 genes. With an ATP4A radioimmunoprecipitation assay, PCA were detected in sera from 20.9% of affected individuals. PCA prevalence increased with age and was greater in females (25.3%) than males (16.5%) and among Hispanics (36.3%) and blacks (26.2%) compared with non-Hispanic whites (20.8%) and Asians (16.7%). PCA and other organ-specific autoantibodies GAD65, IA-2, thyroid peroxidase (TPO), 21-hydroxylase (21-OH), and transglutaminase (TG) clustered within families with heritability estimates from 71 to 95%. PCA clustered with TPO, 21-OH, and persistent GAD65 autoantibodies but not with celiac (TG) or IA-2 autoantibodies. PCA-positive subjects showed an increased frequency of DRB1*0404, DPB1*0201, and PTPN22 R620W (rs2476601-T) and a decreased frequency of DRB1*0101, DPB1*0301, and CTLA4 CT60 (rs3087243-T). Genetic variants accounted for 4-5% of the heritable risk for PCA. The same alleles were associated with other autoantibody phenotypes in a consistent pattern. Whereas most of the heritable risk for PCA and other antibodies reflects genetic effects that are tissue specific, parietal cell autoimmunity is a major pathogenetic contributor in APS2.
Asunto(s)
Autoanticuerpos/sangre , Diabetes Mellitus Tipo 1/inmunología , ATPasa Intercambiadora de Hidrógeno-Potásio/inmunología , Adolescente , Adulto , Anciano , Antígeno CTLA-4/genética , Niño , Preescolar , Diabetes Mellitus Tipo 1/sangre , Diabetes Mellitus Tipo 1/epidemiología , Femenino , Frecuencia de los Genes , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Cadenas beta de HLA-DP/genética , Cadenas HLA-DRB1/genética , Humanos , Lactante , Masculino , Persona de Mediana Edad , Células Parietales Gástricas/inmunología , Prevalencia , Proteína Tirosina Fosfatasa no Receptora Tipo 22/genética , Adulto JovenRESUMEN
BACKGROUND: Low expression of HLA class II antigens has been associated with more aggressive disease in several human malignancies including adult adrenocortical tumors (ACT), but their clinical relevance in pediatric ACT needs to be investigated. PROCEDURE: This study analyzed the expression profile of three class II histocompatibility genes (HLA-DRA, HLA-DPA1, and HLA-DPB1) in 58 consecutive pediatric ACT (13 adenomas and 45 carcinomas) by quantitative real time PCR and their association with clinical and biological features. HLA-DPA1 protein level was determined by immunohistochemistry. RESULTS: A significant association (P < 0.01) was observed between lower expression levels of the three genes analyzed and poor prognostic factors such as age ≥ 4 years, tumor size ≥ 200 cm(3), tumor weight ≥ 100 g, and metastatic disease; the presence of an unfavorable event and death. Underexpression of the HLA-DRA, HLA-DPA1, and HLA-DPB1 genes were associated with lower 5-year event-free survival (EFS) (P = 0.017, P < 0.001, and P = 0.017, respectively). Cox multivariate analysis showed that HLA-DPA1 was an independent prognostic factor (P = 0.029) when analyzed in association with stage IV, age and tumor size. Significantly lower EFS was also observed in patients with negative/weak immunostaining for HLA-DPA1 (P = 0.002). Similar results were observed when only patients classified as having carcinomas were analyzed. CONCLUSION: Our results suggest that lower expression of HLA-DRA, HLA-DPA1, and HLA-DPB1 genes may contribute to more aggressive disease in pediatric ACT. HLA-DPA1 immunostaining may represent potential aggressiveness marker in this tumor.
Asunto(s)
Neoplasias de la Corteza Suprarrenal/inmunología , Cadenas alfa de HLA-DP/genética , Cadenas beta de HLA-DP/genética , Cadenas alfa de HLA-DR/genética , Adolescente , Neoplasias de la Corteza Suprarrenal/mortalidad , Neoplasias de la Corteza Suprarrenal/patología , Niño , Preescolar , Femenino , Cadenas alfa de HLA-DP/análisis , Cadenas beta de HLA-DP/análisis , Cadenas alfa de HLA-DR/análisis , Humanos , Lactante , Masculino , PronósticoRESUMEN
Genetic polymorphism of human leukocyte antigen (HLA)-DPA1 and -DPB1 loci was studied in 154 unrelated individuals from Guadeloupe, an archipelago of five islands located in the Carribean Sea. Thirty different DPB1 and eight different DPA1 alleles were observed with a heterozygosity index of 0.87 and 0.78, respectively. This high degree of heterozygosity corresponds with those found in African populations. The DPB1* 01:01:01 allele was most frequent (0.260), followed by 02:01:02 (0.143) and 04:01:01 (0.127). The DPA1 alleles 01:03 (0.380), 02:01 (0.302), 02:02 (0.175) and 03:01 (0.123) were identified in >35 individuals each, whereas 01:04, 01:05 and 04:01 were present only once. Haplotype estimations revealed the presence of 39 different haplotypes, with DPB1*01:01:01-DPA1*02:02 and DPB1*02:01:02-DPA1*01:03 as the most frequent (0.143 and 0.140, respectively). A striking difference was observed in DPB1/DPA1 associations between DPB1*04:02 and *105:01, that have identical exon 2 sequences. DPB1*04:02 was exclusively associated with DPA1*01:03, whereas DPB1*105:01 was present with DPA1*03:01, *03:02 or *04:01. This implies that the DP molecules are actually different, and this difference is relevant to consider in studies on the function of HLA-DP molecules in transplantation. Overall, HLA-DPA1 and DPB1 allele frequencies and haplotypes of the population of Guadeloupe were most similar to African populations, with characteristic alleles and haplotypes that bespeaks the admixture with other ethnicities.
Asunto(s)
Alelos , Frecuencia de los Genes/genética , Genética de Población , Cadenas alfa de HLA-DP/genética , Cadenas beta de HLA-DP/genética , Haplotipos/genética , Adulto , Secuencias de Aminoácidos , Preescolar , Epítopos/química , Epítopos/inmunología , Femenino , Guadalupe , Humanos , MasculinoRESUMEN
The new HLA-DPB1*142:01 allele differs from DPB1*26:01:02 and DPB1*56:01 at codons 65 (I65>L65) and 35 (F35>Y35), respectively.
Asunto(s)
Alelos , Rechazo de Injerto , Cadenas beta de HLA-DP/genética , Trasplante de Riñón , Polimorfismo de Nucleótido Simple , Secuencia de Bases , Codón , Exones , Resultado Fatal , Prueba de Histocompatibilidad , Humanos , Datos de Secuencia Molecular , Perú , Alineación de Secuencia , Análisis de Secuencia de ADN , Donantes de TejidosAsunto(s)
Exones/genética , Cadenas beta de HLA-DP/genética , Trasplante de Células Madre Hematopoyéticas , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Secuencia de Bases , Niño , Familia , Prueba de Histocompatibilidad , Humanos , Masculino , Datos de Secuencia Molecular , Polimorfismo Genético , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Alineación de Secuencia , Trasplante , VenezuelaRESUMEN
Three different Venezuelan Amerindian tribes were studied for human leukocyte antigen (HLA)-DPA1 and DPB1 allelic variability using polymerase chain reaction-sequence-specific oligonucleotide probes (PCR-SSOP) and sequence-based typing in a selected group of samples. These tribes are geographically (two from the Perija Mountain range and one from the Orinoco Delta) and linguistically distinct: the Bari (from Campo Rosario and Saymaidoyi villages) and the Warao have been classified within the Chibcha linguistic family, whereas the Yucpa (from the Aroy, Marewa, and Peraya villages) are Carib speaking. Venezuelan Indians, like other Native American tribes, show a markedly reduced number of different HLA-DP alleles (range, 2-7) and haplotypes (range, 4-11) in comparison with neighboring Venezuelan mestizo and other non-Indian populations. Some HLA-DPB1 (*0402 and *1401) alleles characteristic for all Amerindian tribes are present also in these populations. Despite general similarities, each tribe and, in some cases, some subtribes show their own pattern of allele and haplotype distribution apparently more as a result of linguistic than to geographic variation.
Asunto(s)
Antígenos HLA-DP/genética , Alelos , Frecuencia de los Genes , Variación Genética , Cadenas alfa de HLA-DP , Cadenas beta de HLA-DP , Haplotipos , Humanos , Indígenas Sudamericanos/clasificación , Indígenas Sudamericanos/genética , Lingüística , Filogenia , Polimorfismo Genético , VenezuelaRESUMEN
Genetic associations between type 1 diabetes and alleles at the HLA class II locus DPB1 have been previously reported. Observed associations could be due to variation in the DPB1 locus itself or to linkage disequilibrium (LD) between DPB1 alleles and other susceptibility loci. One measure of whether the association of an allele with a disease reflects a true effect of the locus or is simply due to LD is the observation of that association in multiple ethnic groups. Previous type 1 diabetes associations have been reported for DPB1*0301 and DPB1*0202 (predisposing) and for DPB1*0402 (protective). In this study, results are reported from testing these associations in three different sample sets: 1) Puerto Rican case and control subjects, 2) Mexican-American simplex families, and 3) high-risk (DR3/DR4) individuals with and without an affected relative. DPB1*0301 was associated in all three groups, even after accounting for LD with DRB1-DQB1. DPB1*0202 and DPB1*0402 were positively and negatively associated, respectively, in two of the three populations. These results suggest that the observed DPB1 associations, especially that of the DPB1*0301 allele, with type 1 diabetes are likely to be true associations. This supports the concept that multiple genes in the HLA region can affect type 1 diabetes susceptibility.
Asunto(s)
Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/inmunología , Etnicidad/genética , Predisposición Genética a la Enfermedad/genética , Antígenos HLA-DP/genética , California , Colorado , Antígenos HLA-D/genética , Cadenas beta de HLA-DP , Hispánicos o Latinos , Humanos , Americanos Mexicanos , Puerto RicoRESUMEN
The Martinican population is mainly the product of admixture between African people and French Caucasians. The aim of the present study is to investigate at the DNA level the polymorphism of HLA class I (HLA-A, HLA-B) and class II (HLA-DRB1, DQB1 and DPB1) genes in a population of 100 Martinicans. Allelic distributions and interlocus linkage disequilibria were compared to those observed in a French Caucasian population and in African or North American African populations. Our data revealed a higher degree of polymorphism in Martinicans than in Caucasians and showed a prominant contribution of African origin in the admixed genetic feature of this population. African characteristic alleles were significantly represented in Martinicans: A*30, *33 *34, *66, *74, *8001, B*1510, *35, *42, *53, DRB1*0302, *0804, *1202, *1304, *1503, DPB1*0101, *1701, *1801, *3901. Moreover a higher diversity of A*-B* and DRB1*-DQB1* associations was observed in Martinicans compared to Caucasians which also reflects the African genetic background of this population. In the whole, using PCR-based genotyping methods for HLA class I and class II loci, this study allows a preliminary description of HLA allele distribution in this Caribbean island and gives new elements which may be helpful in the anthropologic field as well as in HLA and disease association studies.
Asunto(s)
Alelos , Genes MHC Clase II/genética , Genes MHC Clase I/genética , Haplotipos , África/etnología , Población Negra/genética , Francia/etnología , Frecuencia de los Genes , Marcadores Genéticos , Antígenos HLA-A/genética , Antígenos HLA-B/genética , Antígenos HLA-DP/genética , Cadenas beta de HLA-DP , Antígenos HLA-DQ/genética , Cadenas beta de HLA-DQ , Antígenos HLA-DR/genética , Cadenas HLA-DRB1 , Humanos , Desequilibrio de Ligamiento , Martinica , Polimorfismo Genético/genética , Población Blanca/genéticaRESUMEN
Trypanosomiasis is an important cause of cardiomyopathy in endemic rural areas of Latin America. Previous studies have suggested participation of HLA molecules in the immune response regulation of T. cruzi infection, and association of HLA antigens with heart damage. One hundred and eleven unrelated T. cruzi antigen-seropositive individuals were tested for HLA class II alleles by the polymerase chain reaction and sequence specific oligonucleotide (PCR-SSO) method. Patients were classified in 3 groups according to clinical and electrocardiographic characteristics: asymptomatics (group A), with arrhythmia (group B), and with overt congestive heart failure (group C). Statistical analysis confirmed the significant increment of the DRB1*01 DQB1*0501 haplotype (p = 0.03) previously reported by our laboratory in patients with cardiomyopathy. The DPB1*0401 allele frequency is also significantly increased in patients with heart disease (groups B + C) (p = 0.009) while DPB1*0101 frequency is higher among the asymptomatic group (p = 0.04) compared with individuals of group C. The DPB1*0401 allele in homozygous form or in combination with allele DPB1*2301 or 3901, was found present more often in patients of groups B and C. Thus, the combination of two of these three alleles, sharing specific sequence motifs in positions 8, 9, 76, and 84-87 confers a relative risk of 6.55 to develop cardiomyopathy in seropositive patients (p = 0.041). Furthermore, 32% of the cardiomyopathics have either DRB1*01 DQB1*0501 and/or DPB1*0401/*0401, 0401/*2301, or* 0401/*3901 compared with 9% of the seropositive asymptomatics (OR = 5.0; p = 0.006).
Asunto(s)
Cardiomiopatía Chagásica/genética , Antígenos HLA-DP/genética , Antígenos HLA-DQ/genética , Antígenos HLA-DR/genética , Polimorfismo Genético , Secuencia de Aminoácidos , Animales , Cardiomiopatía Chagásica/inmunología , Frecuencia de los Genes , Genes MHC Clase II , Predisposición Genética a la Enfermedad , Cadenas beta de HLA-DP , Cadenas beta de HLA-DQ , Cadenas HLA-DRB1 , Haplotipos , Humanos , Datos de Secuencia Molecular , Homología de Secuencia de Aminoácido , VenezuelaRESUMEN
The alleles at the HLA class II loci HLA-DRB1, DQA1, DQB1 and DPB1 were determined for 49 individuals of the Ticuna, a Native South American population living in Brazil, using PCR/SSO probe hybridization and DNA sequencing. A newly described DRB1*08 variant, DRB1*0807, which has previously been reported only in native Colombians and contemporary Brazilians of African and Caucasian descent, was identified in the Ticuna at a high frequency (f=0.225). Because *0807 has been observed only in South American populations, we propose that it was generated from a parental *0802 allele recently, after the isolation of various Native South American populations, and infer that the DRB1*0807 allele was generated by a C to T change at codon 57 (Asp-->Val, GAT-->GTT) from the ancestral *0802. This inference is supported by the sequence of a complex VNTR in the second intron of the DRB1 gene. The DPB1 alleles *0401, *0402 and *1401 constituted 76% of the observed Ticuna DPB1 alleles (f=0.166, 0.427 and 0.166 respectively). In addition, the DPB1 allele *3501, which has been observed in a few other Native South American groups, was observed at a frequency of 0.053 and may have been generated from the putative ancestral allele *1401 allele in South America. The DRB1 and DPB1 allele frequencies for the Ticuna deviate from expected Hardy-Weinberg equilibrium proportions, while DQA1 and DQB1 allele frequencies do not. When this deviation, which involves an observed excess of DRB1*0807 heterozygotes, is considered with the high frequency of the DRB1*0807 and DPB1*1401 alleles, we infer that native South American populations may have been under selection pressure for increased allele diversity.
Asunto(s)
Alelos , Evolución Molecular , Antígenos HLA-DR/genética , Indígenas Sudamericanos/genética , Polimorfismo Genético , África , Brasil/etnología , Mapeo Cromosómico , ADN Mitocondrial , Frecuencia de los Genes , Antígenos HLA-DP/genética , Cadenas beta de HLA-DP , Antígenos HLA-DQ/genética , Cadenas alfa de HLA-DQ , Cadenas beta de HLA-DQ , Cadenas HLA-DRB1 , Haplotipos , Homocigoto , Humanos , Desequilibrio de Ligamiento , Modelos GenéticosRESUMEN
HLA class II variation was analyzed in nine Native American populations of Colombia using PCR/SSOP typing methods. Under the auspices of the Expedition Humana, approximately 30 unrelated native Colombia Indian samples each from the Tule (NW Pacific Coast), Kogui (Sierra Nevada). Ijka (Sierra Nevada), Ingano (Amazonas), Coreguaje (Amazonas), Nukak (Amazonas), Waunana (Pacific), Embera (Pacific) and Sikuani (Northeastern Plains) were collected and analyzed at the DRBI, DQA1, DQB1 and DPB1 loci. The number of different DRB1, DQA1, DQB1 and DPB1 alleles in the Colombian Indians is markedly reduced in comparison with neighboring African Colombian populations, which exhibit a very high degree of class II variability, as discussed in an accompanying paper. In the Colombian Amerindian groups, DR2 (DRB1*1602), DR4 (DRB1*0407, *0404, *0403 AND *0411), DR6 (DRB1*1402) and DR8 (DRB1*0802) comprise > 95% of all DRB1 alleles. We also found an absence of DR3 in all populations, and DR1, DR7 and DR9 allelic groups were either very rare or absent. Each Colombian Amerindian population has a predominant DRB1 allele (f = approximately 0.22-0.65) and DRB1-DQA1-DQB1 haplotype. Several novel DR-DQ haplotypes were also found. At the DPB1 locus, DPB1*0402 (f = 0.28-0.82), *1401 (f = 0.03-0.45), and *3501 (f = 0.03-0.27), were the three most prevalent alleles, each population maintaining one of these three alleles as the predominant (f > 0.26) DPB1 allele. The reduction of diversity for the HLA class II alleles in the Colombian Indians is suggestive of a population bottleneck during the colonization of the Americans, with little to no subsequent admixture with neighboring African Colombian populations in the last approximately 300 years.