A or AB? Resolving the dilemma of weaker subgroup through serological evaluation: Reporting two cases from...

Blood group discrepancies and their resolution can sometimes become tricky when it comes to weaker subgroups. A number of weaker B subgroups, which are very infrequently encountered, have been described, including B₃, B_x, B_m, and B_el. The varied serologic reactivity of these subgroups, using routine human polyclonal antisera, usually startles the personnel involved in such blood group discrepancies and interpretation is either delayed or incorrect. Here, we present two cases of AB Rh (D) positive with weak B subgroups, detected in two whole blood donors. Their red cells showed strong agglutination with anti-A, anti-AB, and anti-D, no reaction with anti-B, and serum showed no reaction with A1, A2, B, and O cells. Adsorption-elution procedure and salivary testing suggested the presence of a weaker B subgroup (B_el). Hence, AB_el subgroup was reported for both the donors. Resolution of blood group discrepancies is crucial, as it would aid to prevent hemolytic transfusion reactions due to inaccurate blood group interpretation.