Variant rh alleles and rh immunisation in patients with sickle cell disease

Alloimmunisation is a major complication in patients with sickle cell disease (SCD) receiving red blood cell (RBC) transfusions and despite provision of Rh phenotyped RBC units, Rh antibodies still occur. These antibodies in patients positive for the corresponding Rh antigen are considered autoantibodies in many cases but variant RH alleles found in SCD patients can also contribute to Rh alloimmunisation. In this study, we characterised variant RH alleles in 31 SCD patients who made antibodies to Rh antigens despite antigen-positive status and evaluated the clinical significance of the antibodies produced. RHD and RHCE BeadChip™ from BioArray Solutions and/or amplification and sequencing of exons were used to identify the RH variants. The serological features of all Rh antibodies in antigen-positive patients were analysed and the clinical significance of the antibodies was evaluated by retrospective analysis of the haemoglobin (Hb) levels before and after transfusion; the change from baseline pre-transfusion Hb and the percentage of HbS were also determined. We identified variant RH alleles in 31/48 (65%) of SCD patients with Rh antibodies. Molecular analyses revealed the presence of partial RHD alleles and variant RHCE alleles associated with altered C and e antigens. Five patients were compound heterozygotes for RHD and RHCE variants. Retrospective analysis showed that 42% of antibodies produced by the patients with RH variants were involved in delayed haemolytic transfusion reactions or decreased survival of transfused RBC. In this study, we found that Rh antibodies in SCD patients with RH variants can be clinically significant and, therefore, matching patients based on RH variants should be considered.Alloimmunisation is a major complication in patients with sickle cell disease (SCD) receiving red blood cell (RBC) transfusions and despite provision of Rh phenotyped RBC units, Rh antibodies still occur. These antibodies in patients positive for the corr1317277FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOsem informaçã

Genetic polymorphisms of Rh, Kell, Duffy and Kidd systems in a population from the State of Paraná, southern Brazil

BACKGROUND: Red blood group genes are highly polymorphic and the distribution of alleles varies among different populations and ethnic groups. AIM: To evaluate allele polymorphisms of the Rh, Kell, Duffy and Kidd blood group systems in a population of the State of Paraná METHODS: Rh, Kell, Duffy and Kidd blood group polymorphisms were evaluated in 400 unrelated blood or bone marrow donors from the northwestern region of Paraná State between September 2008 and October 2009. The following techniques were used: multiplex-polymerase chain reaction genotyping for the identification of the RHD gene and RHCE*C/c genotype; allele-specific polymerase chain reaction for the RHDΨ and restriction fragment length polymorphism polymerase chain reaction for the RHCE*E/e, KEL, FY-GATA and JK alleles. RESULTS: These techniques enabled the evaluation of the frequencies of Rh, Kell, Duffy and Kidd polymorphisms in the population studied, which were compared to frequencies in two populations from the eastern region of São Paulo State. CONCLUSION: The RHCE*c/c, FY*A/FY*B, GATA-33 T/T, JK*B/JK*B genotypes were more prevalent in the population from Paraná, while RHCE*C/c, FY*B/FY*B, GATA-33 C/C, JK*A/JK*B genotypes were more common in the populations from São Paulo.212

Blood group and HLA polymorphisms in patients with myelodysplastic syndrome and their implications in erythrocyte alloimmunization

Orientadores: Lilian Maria de Castilho, Jeane Eliete Laguila VisentainerTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências MédicasResumo: A síndrome mielosplásica (SMD) correponde a um grupo de distúrbios clonais heterogêneos decorrente de um defeito intrínseco das células progenitoras hematopoéticas, resultando em insuficiência da medula óssea, desencadeando anemia com dependência de transfusões sanguíneas e infecções decorrentes da neutropenia. Embora a terapia transfusional seja segura, muitos desses pacientes correm risco de complicações relacionadas à sobrecarga de ferro e à aloimunização contra antígenos de grupos sanguíneos, que muitas vezes dificulta a busca de sangue compatível para esses pacientes, além estar associada a reações hemolíticas transfusionais tardias e formação de auto-anticorpos. A compatibilidade para antígenos Rh e K tem sido utilizada na tentativa de reduzir a formação de anticorpos em pacientes que recebem transfusões crônicas, mas a fenotipagem estendida, incluindo os antígenos Fya e Jka, também tem sido recomendada. Este estudo teve como objetivos avaliar o perfil transfusional dos pacientes com SMD, propor um protocolo de compatibilidade molecular para seleção de sangue fenótipo compatível e avaliar uma possível associação dos alelos HLA com a susceptibilidade ou proteção a aloimunização eritrocitária. Foram analisados 61 pacientes portadores de SMD, sendo 18 pacientes não transfundidos e 43 pacientes submetidos à terapia transfusional com e sem formação de anticorpos. Realizamos genotipagem para os alelos de grupos sanguíneos RHD, RHCE, FY, DO, CO, DI, SC, GYPA, GYPB, LU, KEL, JK e LW e para os alelos HLA classe I e classe II nas amostras dos pacientes e comparamos os resultados com grupos- controle. Com relação ao perfil transfusional dos pacientes estudados, a maioria recebe transfusões sanguíneas regulares e 44% encontra-se aloimunizada. Os principais aloanticorpos detectados foram contra antígenos Rh e K. Verificamos que a genotipagem é superior a fenotipagem para determinação dos antígenos de grupos sanguíneos e que a compatibilidade molecular para Rh e K seria suficiente para evitar a aloimunização eritrocitária na maioria dos pacientes. Nossos resultados também mostraram uma associação entre o alelo HLA-DRB1*13 e a proteção à aloimunização contra antígenos de grupos sanguíneos em pacientes com SMDAbstract: The myelodysplastic syndrome (MDS) is a group of heterogeneous clonal disorder caused by an intrinsic stem cell defect with propensity to the bone marrow failure that results in the transfusion dependence and neutropenic infection. Although blood transfusion is generally safe, many of those patients are at risk of transfusion-related complications such as iron overload and RBC alloimmunization that often makes finding compatible RBC products difficult and is also associated with delayed hemolytic transfusion reactions (DHTRs) and autoantibody formation. Matching for Rh and K antigens has been used in an attempt to reduce antibody formation in patients receiving chronic transfusions but an extended phenotyping matching including Fya and Jka antigens has also been recommended. This study was aimed to identify the transfusion profile of the patients with myelodysplastic syndrome (MDS), an efficient transfusion protocol of genotype matching and a possible association of HLA class alleles with susceptibility or protection to RBC alloimmunization. We evaluated 61 patients with MDS, 18 not transfused and 43 undergoing transfusion therapy with and without antibody formation. We performed genotyping for RHD, RHCE, FY, DO, CO, DI, SC, GYPA, GYPB, LU, KEL, JK e LW and for HLA class I and class II alleles in the patient DNA samples and compared the results with a control group. We verified that the majority of patients have regular transfusions and 44% are alloimmunized to RBC antigens. Blood group genotyping was superior to phenotyping to determine the antigen profile in those patients and molecular matching for Rh and K would be enough for most of the patients. Our results also showed a significant association of HLA-DRB1*13 with protection to RBC alloimmunization in patients with MDSDoutoradoClinica MedicaDoutora em Clínica Médic