[Molecular basis of the B(A) phenotype]

Area of Science:

• Immunology
• Genetics
• Transfusion Medicine

Background:

• The B(A) blood group phenotype is a rare serological variant.
• Understanding its genetic basis is essential for safe blood transfusion practices.

Purpose of the Study:

• To characterize the serological and molecular aspects of a B(A) phenotype.
• To assess transfusion safety in an individual with this rare blood group.

Main Methods:

• Serological testing to confirm the B(A) phenotype.
• Polymerase chain reaction-sequence specific primer (PCR-SSP) and DNA sequencing for genotyping.
• Review of blood transfusion clinical data.

Main Results:

• The proband exhibited both A and B antigens on red blood cells and anti-A in serum.
• Genotyping revealed a B(A)02/O02 genotype with specific mutations in the ABO locus.
• Transfusion with A2B donor blood was compatible and safe, with no adverse reactions.

Conclusions:

• The nucleotide change 700C>G in the B allele can lead to the B(A) phenotype, mimicking A2B.
• Individuals with the B(A) phenotype can be safely transfused with blood from A2B donors.