Retrospective analysis of molecular biology mechanism of ABO blood group typing discrepancy among blood donors in Jinan blood station

A novel allele of B(A) blood group detected in a donor and a patient during a retrospective review of ABO group anomalies in a tertiary hospital

BACKGROUND

ABO discrepancies, inconclusive results between forward and reverse typing, are one of the significant challenges encountered in transfusion medicine. Their frequency and etiologies can vary among ethnicities. This study aimed to characterize ABO discrepancies in a Thai population.

METHODS

We conducted a retrospective review of 285,450 donor and 258,780 patient samples for ABO discrepancies, which were categorized into five groups, as described below. The serological ABO grouping was performed using an automated system, and further serological techniques were used in the discrepancy cases. Additionally, sequencing was used to examine the genetic background of the B(A) phenotype detected during the retrospective review.

RESULTS

ABO discrepancies were identified in 396 patients (0.15 %) and 74 blood donors (0.03 %). Among the patients, the most frequent cause was ABO mismatch stem cell transplantation (198; 50 %). The remaining 198 discrepancy cases (198/258,780; 0.08 %) were categorized into five groups: weak/missing red cell reactivity, extra red cell reactivity, mixed-field, weak/missing serum reactivity, and extra serum reactivity, accounting for 17.17 %, 0.51 %, 29.29 %, 28.79 %, and 24.24 %, respectively. For the blood donors, the percentages were 48.65 %, 2.70 %, 2.70 %, 37.84 %, and 8.11 %, respectively. We also identified the B(A) phenotype in one patient and two blood donors. The sequencing study identified allele variants of c.467 C>T, c.796 C>A, c.803 G>C, and c.930 G>A in exon 7, which was a novel allele.

CONCLUSION

ABO discrepancies were distinct between donors and patients even in the same ethnicity. This finding highlighted the influence of the patient's conditions and therapy on the anomalous ABO typing. Additionally, the B(A) individuals identified in this study carried identical genetic alterations that differed from all antecedent alleles of the B(A) phenotype.

Molecular genetic mechanism analysis and pedigree investigation of rare Bweak subgroup

OBJECTIVE

To analyze the molecular mechanism of rare B_weak subgroup in the ABO blood group system and conduct pedigree investigations.

METHODS

The blood group was detected by conventional serological method, and ABO gene of proband and her family was amplified and sequenced by polymerase chain reaction method.

RESULTS

The study showed that the proband was a B_weak phenotype by conventional serological method. Her family's serological results were as follows, her father and eldest brother were B_weak subgroup while her mother and second eldest brother were O group. The proband's ABO gene sequencing result was ABO*BW.27/ABO*O.01.02. Her father, mother and two elder brothers were ABO*BW.27/ABO*O.01.01, ABO*O.01.01/ABO*O.01.02, ABO*BW.27/ABO*O.01.02, ABO*O.01.01/ABO*O.01.02.

CONCLUSION

Conventional blood group serology combined with molecular diagnostic technology can accurately identify the B_weak subgroup, and the pedigree investigation analysis showed that the proband's allelic mutation came from her father. She has gained a point mutation of c.905A>G on the basis of ABO*B.01.