Characterization of a novel B(A) allele with BBBA type at the ABO blood group.

The ABO blood group is one of the main blood group systems, and it plays an important role in transfusion medicine and transplantation. To date, most of the many ABO subgroups with a weak expression of the A or B antigen on red blood cells have been elucidated to have specific molecular genetic background with respect to the ABO gene. The ABO*B(A) allele or CisAB allele is a type of dual ABO allele which can encode glycosyltransferases responsible for the conversion of H substance to both A and B antigen. We report here our characterization of a novel B(A) allele which differs from those reported previously.