Application of RHD and RHCE genotyping for correct blood group determination in chronically transfused patients

BACKGROUND: In chronically transfused patients, conventional blood group ty ping may be impossible because of mixed-field agglutination. STUDY DESIGN AND METHODS: In 27 patients with congenital anemia and lifelon g transfusion history, genotyping for D, RHD, and RHCE was performed with p olymerase chain reactions. These results were compared with the blood group typing results documented in the medical record. RESULTS: Two of 27 cases had been typed D-negative by serologic tests and D -positive by genotyping. In 20 patients, the CDE formula had been determine d serologically according to the medical record; 4 of these patients were C c by serologic tests and C/C by genotyping. One patient typed ee by serolog ic tests, and genotyping revealed heterozygosity (E/e). CONCLUSION: In patients with a lifelong transfusion history, serologic bloo d group determination may be impossible, and pretransfusion test results ar e not always available or reliable. In whites, Rh-matched transfusions are possible with genotyping. The genetic background of the RH genes has to be elucidated in other ethnic groups, such as in black patients with sickle ce ll disease; before genotyping can be applied without restriction.