RESUMO
BACKGROUND: In chronically transfused patients, the classical hemagglutination assays may be inaccurate in defining the RBC phenotypes of the patients due to previous transfusions. DESIGN: DNA samples from 39 multi-transfused patients including thalassemia and sickle cell disease were used for red blood cell genotyping. The Rh-Type and KKD-Type (BAGene, BAG Healthcare) were used to determine the polymorphisms associated with antigen expression for RHD, RHCE and Kell, Kidd, Duffy blood group systems, respectively. Results were compared with previously determined phenotyping results for RhD, RhCcEe and Kell by hemagglutination method. RESULTS: Nineteen out of the 37(51%) patients had discrepancies between genotyping and phenotyping results in a total of 25 alleles. In 12 patients, the discrepancies had the potential of alloimmunization. CONCLUSION: Blood group genotyping has vital importance in transfusion management of chronically transfused patients especially if the patients were not phenotyped before starting the initial transfusions.