Three new high-prevalence antigens in the Cromer blood group system

BACKGROUND: The Cromer blood group system consists of nine high-prevalence and three low-prevalence antigens carried on decay-accelerating factor (DAF). This report describes three new Cromer high-prevalence antigens, named ZENA, CROV, and CRAM. STUDY DESIGN AND METHODS: Sequence analyses were performed on DNA from three probands whose serum samples each contained an alloantibody to a high-prevalence antigen in the Cromer blood group system. Polymerase chain reaction-restriction fragment length polymorphism analysis to detect the mutation encoding the CROV– phenotype was performed on 100 Croatian donors. To map the respective epitopes, DAF deletion mutants were tested by immunoblotting with eluates containing the antibodies. RESULTS: In each proband, sequence analysis revealed a single-nucleotide substitution in DAF: ZENA, 726T>G mutation, predicted change His242Gln; CROV, 466G>A mutation, predicted change Glu156Lys; and CRAM, 740A>G mutation, predicted change Gln247Arg. By analysis of DAF deletion mutants, the CROV antigenic determinant mapped to the complement control protein (CCP) domain 2, which is encoded by exon 3, whereas ZENA and CRAM mapped to CCP4, which is encoded by exon 6. CONCLUSION: This study describes three novel high-prevalence antigens in the Cromer blood group system each characterized by a predicted single-amino-acid substitution. The antigens have been assigned the following International Society of Blood Transfusion (ISBT) numbers: ZENA is CROM13, CROV is CROM14, and CRAM is CROM15.