LAUSR

We here report the first study of antigen and phenotype frequencies of Rh (C, c, E, e), M, Mia and Kidd antigens in north‐east Thai blood donors. Blood transfusion services aim to ensure availability of adequate and safe blood to minimize the development of transfusion reactions. For pre‐transfusion testing, the most important blood group systems are ABO and RhD. The transfusion of ABO‐compatible otherwise unknown phenotype blood may result in alloimmunization, especially in multi‐transfused patients. Extended red blood cell (RBC) phenotyping and selection of blood negative for specific antigens reduce post‐transfusion complications and allow for effective blood transfusion regimens to be achieved. A total of 13,567 regular repeated, voluntary Thai blood donors were included for red‐cell antigen typing of Rh (D, C, E, c, e). Samples from 12,768, 9,389 and 13,059 donors were typed for Kidd, M and Mia antigens, respectively. Amongst Rh antigens, e was the most common (96.80%) followed by C (95.50%), c (34.40%) and E (32.20%) with CCDee (60.00%) being the most common phenotype. For Kidd phenotypes, Jk(a+b+) was the most common (46.73%) and Jk(a−b−) was rare (0.07%). For the M and Mia antigen, M(+) was most frequently found (94.96%) and Mia(+) was found in 17.97% of individuals. Knowledge of red‐cell antigen phenotype frequencies in a population is helpful for creating a phenotype database of blood donors which can provide antigen‐negative compatible blood to patients with multiple alloantibodies. Moreover, provision of antigen‐matched blood can prevent alloimmunization in multi‐transfused patients.