Though not very frequent, blood group discrepancies are of common occurrence which must be promptly resolved for safe transfusion practices. Blood group discrepancy is defined as the non-corroboration between cell grouping and serum grouping. Variable erythrocyte antigenic expressions (qualitative and/or quantitative difference) owing to allelic heterogeneity, give rise to subgroups. Problems during blood grouping due to weakened expression of antigens are a rare cause for ABO discrepancies. Of note, subgroups of 'B' with decreased expression of the B antigen are of very rare occurrence in the general population. Serologically, the variants of 'B' can be classified into B3, Bx, Bm and Bel. Serological confirmation of such subgroups requires special immuno-haematological procedures. The current study reports 3 cases of subgroups of B (2 cases of Bm and 1 case of Bw) detected at our centre. It is important to detect and resolve discrepant ABO grouping results so as to prevent ABO mis-match transfusions. Such individuals should also be pre-emptively informed of their respective blood donor and transfusion recipient status, as well.
Keywords: ABO blood group; Blood groups; Subgroups of B.