What is the most likely cause of ABO discrepancy in a blood sample showing anti-A 0 and anti-B 0?

The presence of anti-A 0 and anti-B 0 indicates that there is an unexpected result in the typing of the blood sample, which leads to an ABO discrepancy. The most likely explanation for this finding is the weak subgroup of A, which is typically characterized by a reduced amount of A antigen on red blood cells.

Individuals with weak subgroups of A may not exhibit strong reactions with anti-A sera and can even give a negative reaction if the antibody concentration in the test is not sufficient to detect the low levels of antigen present. As a result, the blood sample can yield no reaction with anti-A, thus showing a discrepancy in what is expected based on the characteristics of the A blood group.

While other options present potential scenarios for an ABO discrepancy, they are less likely in this case. Loss of antigen due to disease usually presents with other more pronounced clinical features or reactivity that can be identified, and acquired B typically involves a specific alteration in the antigen expression that is distinct from a weak A subgroup. The Bombay phenotype, which lacks A and B antigens entirely, would also not react with anti-A or anti-B, leading to a different set of typing results. Therefore, identifying a weak subgroup of A is the most fitting explanation for