ABO discrepancies revealing rare weak A subgroups: a 2-case series

Area of Science:

• Transfusion Medicine
• Immunology
• Genetics

Background:

• ABO discrepancies due to weak A subgroups are rare but critical.
• These discrepancies can result in patient mistyping and incorrect transfusion management.

Purpose of the Study:

• To present cases of patients with historically group O typing but weak A subgroups.
• To illustrate the diagnostic challenges and utility of molecular methods in identifying weak A phenotypes.

Main Methods:

• Detailed serologic investigation including forward and reverse typing.
• Use of specific ABO reagents and anti-A,B reagent.
• Molecular genotyping at a reference laboratory.

Main Results:

• Case 1: Weak reactivity with anti-A, anti-A1, and anti-B identified.
• Case 2: Nonreactive with anti-A, reactive with anti-A,B, weak anti-A1/A2 reactivity, and strong anti-B reactivity.
• Molecular genotyping confirmed Aw or Ael alleles in both patients.

Conclusions:

• Weak A subgroups present a variable serologic spectrum.
• ABO reagent sensitivity varies in detecting minimal A antigen expression.
• Molecular characterization is useful for ambiguous serologic findings in weak A phenotypes.