Identification of Bombay blood group of a blood donor by serological and molecular testing

The Bombay blood group, discovered in 1952 in Bombay, is inherited recessively and lacks A, B, and H antigens on red cells and in body secretions. In this case report, we have standardized protocols for Bombay blood group confirmation by advanced serological methods on the blood donor sample. Forward blood grouping showed O RhD positive; reverse grouping showed agglutination with A, B, and O cells. Anti-H lectin testing revealed no agglutination, indicating the absence of H antigen. Direct Coombs test was negative. Antibody screening was pan-reactive. Anti-H titers were 4 at 24°C and 37°C and 8 at 4°C. Donor cells tested with human plasma. Saliva inhibition test confirmed the nonsecretor status of the donor. Molecular analysis of the FUT1 and FUT2 genes was performed. FUT1 gene showed the presence of 725T>G mutation and FUT2 gene deletion was observed. Donor’s blood group confirmed as Bombay phenotype RhD positive.