Estudo de genótipo eritrocitário em doadores de sangue e em 10 politransfundidos pelo Hemocentro Regional de Uberaba/ Fundação Hemominas e Hospital de Clínicas da Universidade Federal do Triângulo Mineiro (UFTM)

Abstract

Introduction: Patients with hemoglobinopathies, onco-hematological diseases and other multitransfused individuals are subject to Red Blood Cell (RBC) alloimmunization, hemolytic reactions and even death because of the high quantity of RBC antigens that might result in incompatibilities between blood donors and patients. These complications can be minimized through RBC genotyping which, however, is not often performed in Brazil. The frequency of RBC genotypes varies according to ethnicity; however, these studies, common in São Paulo10 and Paraná, have not yet been carried out in Minas Gerais, where the Afro-descendant populations are more prevalent. Objectives: research and determine the frequency of genotypes in the Rh, Kell, Duffy and Kidd systems in blood donors and multitransfused patients, compare these frequencies concerning gender and ethnicity, evaluate phenotypes by comparing them to genotypes; and in patients: verify the number of RBC transfusions (total and in the three months before blood collections), the number of transfusions incompatible with the genotypes, the presence of alloantibodies and the number of transfusions in alloimmunized and non-alloimmunized individuals. Methodology: After consent, blood samples were collected from 287 subjects (170 donors and 117 patients) in EDTA (Ethylenediamine Tetraacetic Acid) tubes, which were centrifuged, in order to separate the figurated elements from the plasma. The RBCs were phenotyped for C, c, E, e antigens (Rh system); K, k (Kell); Fya, Fyb (Duffy) and Jka, JKb (Kidd). The patients were also subjected to Direct Antiglobulin Test (DAT). DNA was extracted from the leucocytes and submitted to RBC genotyping (AS-PCR, Multiplex or RFLP) for the alleles RHD, RHD*Ψ - RHD Pseudogene, RHCE*C/c, E/e (Rh system); KEL*1/2 (Kell); FY*A/B, GATA-1 (Duffy) and JK*A/B (Kidd). Clinical and epidemiological data were collected, stored and compared using Mann-Whitney, Chi-Square and Fisher Exact Tests (significance level: 5%). Results: In donors and patients, the most frequent genotypes were: Rh system (RHD pos., RHD*Ψ neg., RHCE*cc, RHCE*ee); Kell (KEL*2/KEL*2); Duffy (FY*B/FY*B, GATA-67t/t); Kidd (JK*A/JK*B). GATA-67 c/c mutation was found in 22.22% of the patients and 7.65% of the donors (p = 0.002). Comparing donors and patients with sickle cell disease, RHD*Ψ was observed in 4.76% of the latter and 0% of the donors (p = 0.027); significant differences also occurred in the GATA-1 region and Kidd system. As for gender, in the donors, GATA-67c/c was 12.94% in men and 2.35% in women (p = 0.034). In the whole population studied, RHD positive, RHCE*cc, FY*B/FY*B, GATA-67c/c and JK*A/JK*A genotypes were more common in the Afro-descendants; RHD negative, RHCE*Cc, FY*A/FY*A, GATA-67t/t, JK*A/JK*B and JK*B/JK*B in the Caucasians. Genotype/phenotype discrepancies were observed in four donors (2.35%) and 42 (35.90%) patients; these individuals received more RBC transfusions (total and in the three months before blood collections), including RBCs with phenotypes incompatible with their own genotypes, in comparison to the patients without discrepancies; significant differences were observed in all these cases. Positive DAT occurred in 50% of the receptors with discrepancies and in 17.33% of the other patients (p < 0.001). Alloimmunization was found in 23 (19.66%) receptors, among which, 13 (56.52%) presented alloantibodies from Rh system. Out of the 42 patients with discrepancies, six11 (14.29%) had a history of alloimmunization and three (7.14%) presented Indirect Antiglobulin Test (IAT) positive after blood collection and also detection of discrepancies. The median of RBC transfusions was nine in the alloimmunized and 7.5 in the non-alloimmunized individuals (p = 0.081). Conclusions: Several genotypic differences were observed in comparison with other studies carried out in São Paulo and Paraná, reinforcing the importance of the study in different regions of the country. As for GATA-67c/c mutation, its higher frequency in the patients was due to the larger number of Afro-descendants in this group, which may also explain the higher rates not only of this mutation as well as RHD*Ψ and JK*A/JK*A in the individuals with sickle cell disease in relation to the donors. In the male donors, the higher frequency of GATA-67c/c was possibly due to the high miscegenation in Brazil. The association between positive DAT and the discrepancies corroborates the need of this test in all multitransfused patients submitted to phenotyping. The high levels of genotype/phenotype discrepancies in these individuals reinforce the importance of the correct definition of their antigenic profiles through RBC genotyping associated to phenotyping. Moreover, a firm and effective action of the Transfusion Committees and policies that lead to the increase of blood donations in the country is necessary, in order to reduce transfusions of incompatible erythrocytes and thereby minimize risks of alloimmunization, post-transfusion hemolytic reaction and even death in multitransfused patients.