Background & objectives: In multitransfused thalassaemic patients, haemagglutination fails to phenotype the patient's blood group antigens due to the presence of donor-derived erythrocytes. DNA-based methods can overcome the limitations of haemagglutination and can be used to determine the correct antigen profile of these patients. This will facilitate the procurement of antigen-matched blood for transfusion to multitransfused patients. Thus, the aim of this study was to compare the serological phenotyping of common and clinically important antigens of Rh, Duffy, Kell, Kidd and MNS blood group systems with molecular genotyping amongst multitransfused thalassaemic patients. Methods: Blood samples from 200 patients with thalassaemia and 100 ‘O’ group regular blood donors were tested using standard serological techniques and polymerase chain reaction-based methods for common antigens/alleles (C, c, D, E, e, Fy a , Fy b , Jk a , Jk b , K, k, M, N, S, s). Results: Genotyping and phenotyping results were discordant in 77 per cent of thalassaemic patients for five pairs of antithetical antigens of Rh, Duffy, Kell and Kidd blood group systems. In the MNS blood group system, 59.1 per cent of patients showed discrepancy. The rate of alloimmunization among thalassaemics was 7.5 per cent. Interpretation & conclusions: Molecular genotyping enabled the determination of the actual antigen profile in multitransfused thalassaemia patients. This would help reduce the problem of alloimmunization in such patients and would also aid in the better management of transfusion therapy.

Background & objectives : Patients with thalasssaemia are at a risk of alloimmunization and the presence of RBC alloantibodies further complicates transfusion therapy. Matching for the critical antigens of Rh, Kell, Kidd and Duffy blood group systems has been shown to minimize alloimmunization. The aim of the present study was to create a database of extensively typed donors for clinically significant and common blood group antigens of Rh, Kidd, Kell and Duffy systems for transfusion therapy of multitransfused thalassaemic patients. Methods : Five hundred O group regular blood donors were phenotyped for Rh, Kell, Duffy and Kidd blood group antigens using haemagglutination technique. Eighty four non-alloimmunized and 15 alloimmunized thalassaemia major patients with known antigenic profiles (determined by polymerase chain reaction with sequence-specific primers) were selected for this study. Results : By analyzing antigen profiles of 500 O group regular donors, a database of 193 donors matching perfectly for Rh, Duffy, Kell and Kidd antigens was prepared for 15 alloimmunized patients. For non-alloimmunized 84 thalassaemic patients, a database of 405 donors was created. Interpretation & conclusions : A database of 500 regular blood donors phenotyped for common antigens of Rh, Duffy, Kell and Kidd blood group systems was created, which would be useful in providing extended antigen-matched RBCs for thalassaemia patients. This will improve the quality and effectiveness of transfusion therapy.