Question

A patient with GI disease is typed as the following:

aA: 4+
aB: 2+
Ac: 0
Bc: 4+
What is the discrepancy and how does it come about?
A. The patient is producing a B subgroup antibody causing the reaction with aB
B. The patient is producing an acquired B caused by the cleavage of sugars on the A antigen
C. The patient has been recently transfused and is producing an aB reaction because of this
D. The patient has cold agglutinin disease

Answer 1

The blood typing discrepancy likely represents an acquired B antigen in a patient with GI disease, caused by the enzymatic alteration of A antigens which mimic B antigens.

Step-by-step explanation:

The discrepancy in the patient's blood typing results suggests the presence of an unexpected reaction in the ABO blood group system. The patient's blood reacts with anti-A (4+ strength) and anti-B (2+ strength), but no reaction with anti-C serum, which is inconsistent with typical ABO blood group antigen expression. The reaction with anti-B (Bc: 4+) is especially strong, which could point to an unusual circumstance.

Considering the provided options, option B describes a scenario where the patient is producing an acquired B antigen. This phenomenon can occur when the patient has gastrointestinal (GI) disease that leads to the exposure and cleavage of sugar on the A antigen, thereby mimicking the B antigen and causing this anomaly in blood typing. The acquired B antigen phenomenon is rare but reported in certain GI conditions.

This condition results from the enzymatic alteration of A antigens to resemble B antigens, potentially creating a discrepancy in blood typing and can happen in patients with certain kinds of GI diseases, which may account for the positive reaction with anti-B serum (aB: 2+, Bc: 4+).