Serology and molecular genetic analysis of weakened expression of ABO blood group antigens in Chinese pediatric population

Abstract

Background - The ABO blood group system is vital for red blood cell antigens. Weakened expression of ABO antigens often leads to misidentification of blood types, challenging transfusion safety.

Materials and methods - Blood samples from 44 cases underwent serological analysis using microcolumn agglutination and tube tests. To investigate genetic variations, we sequenced the promoter region and exons 1-7 of the ABO gene. We also examined the relationship between ABO haplotypes and the presence of rare alleles. We used PolyPhen-2 to predict the structure and function of glycosyltransferase B (GTB) and classify missense variants. We also conducted pedigree analysis on 4 selected cases to further understand the inheritance patterns.

Results - We detected 18 different ABO subgroup alleles in 44 cases of weakened ABO antigen expression. We found 7 subtype A (predominantly A2), 7 subtype B (which included Bw and B3), one cisAB, and 3 group B(A). The complete phenotypes we observed included A2, Bw, B3, A2B, ABw, AB3, cisAB, and B(A). Notably, we discovered a rare B allele characterized by the c.538C>T variant, which alters residue 180 to p.Arg180Cys. This variant received a PolyPhen-2 score of 1.00, suggesting a high likelihood of damaging effects. Furthermore, pedigree analysis supported an autosomal inheritance pattern for this allele.

Discussion - The weakened expression of ABO antigens in young children may result from their immature immune systems or subtyping. ABO genotyping is essential to accurately identify blood groups and ensure transfusion safety.