Detection of rare blood group Ax phenotype in blood donor

Background: Karl Landsteiner discovered ABO blood group system in early 20th century, but still, uncertainty remains in immune-hematology while detection of ABO subgroups or weaker variants. The presence of weak subgroups in blood donor samples gives rises to discrepancy in forward (cell) and reverse (serum) grouping. Methods and Materials: We here report a case of the 'A' weak Rh 'D' Positive, Probably Ax Phenotype in a blood donor who came for replacement donation at our blood bank. The blood group discrepancy was resolved by using serological testing, Adsorption elution technique and saliva secretor study. Results: Blood grouping by the tube technique showed no reaction was shown with anti-B, a faint reaction with anti-A, 1+ agglutination with Anti-AB, and a significant reaction (4+) with anti-D and anti-H. The patient's serum showed the presence of anti-B antibody as well as anti-A1. Result for eluate showed microscopic agglutination (1+) with group A cells and a negative reaction with group B cells and saliva secretor study showed having only H substance. Conclusion: This report highlights the importance of cell and serum grouping in solving blood group discrepancy in blood donors. This rare phenotype in a donor is first of its kind reported from India.