Study on the Bw11 subtype caused by the 695 T>C mutation in exon 7 of the ABO blood group gene

Abstract

Objective To identify the rare ABO*BW.11/ABO*O.01.02 subtype in the Yi ethnic group in China, and to investigate the blood group serological characteristics, molecular mechanisms, and genetic background of the ABO*BW.11/ABO*O.01.02 subtype. Methods The proband was a 25-year-old pregnant woman, with ABO typing discre-pancy in routine tests on admission. Due to the inability to accurately identify the conventional ABO blood serology, exons 1-7 of the ABO gene were analyzed by sequencing using the Sanger method, and the effect of the mutation at this site on the structure and function of B glycosyltransferase was predicted using the amino acid series homology modelling of wild-type B glycosyltransferase. Results The blood group serological results of the proband and lineage were inconsistent with the typical B subtype. ABO gene sequencing unveiled a c.695T>C missense mutation in exon 7 of the ABO blood group gene in the 7 probands and family members in 4 generations, leading to the substitution of leucine by proline at position 232 of the B glycosyltransferase. Homology modeling showed that the mutation influenced the peptide and hydrogen bonds of the protein, which probably led to structural and functional alterations, diminished B-glycosyltransferase activity, and weakened expression of the B antigen. Conclusions This proband carries a point mutation in the ABO allele in exon 7 c.695T>C.P.leu 232 Pro to form the ABO*BW.11/ABO*O.01.02 subtype, and is stably inherited in multiple members of this family.

Keywords

• |abo subtype|gene mutation|bw isoform|b glycosyltransferase