The novel variant c.122delG on the ABO*B3.0x allele associated with B3 phenotype

Introduction: B3 is known to be one of the B subtypes that is characterized by serologic mixed-field agglutination. The proportion of Chinese Han individuals with the B3 subtype (B type) and AB3 subtype (AB type) is about 1/900 and 1/1800 respectively. Here, we identified a novel ABO subgroup allele that caused B3 phenotype. Methods: The ABO phenotypes of the proband and his father were typed with the traditional test tube method. The ABO genotype was analyzed by SMRT sequencing. Results: A c.122delG variant was identified in both the proband and his father, who exhibited the B3 phenotype. This variation results in a premature stop codon, leading to mixed field agglutination of the serological B antigen. Conclusion: The novel variation of c.122delG in the exon 3 of ABO*B3.0x allele were identifed in Chinese individuals, resulting in mixed field agglutination of B antigen expression and the formation of ABO subtypes.