RHCE*ceAR encodes a partial c (RH4) antigen

Thr Rh blood group system is highly complex both in the number of discreet antigens and in the existence of partial antigens, especially D and e. Recently, several partial c antigens have been reported. Here we report findings on an African American man with sickle cell disease whose RBCs typed C+c+ and whose plasma contained anti-c. Hemagglutination tests, DNA extraction, PCR-RFLP, reticulocyte RNA isolation, RT-PCR cDNA analyses, cloning, and sequencing were performed by standard procedures. RBCs from the patient typed C+c+ but his plasma contained alloanti-c. DNA analyses showed the presence of RHCE*Ce in trans to RHCE*ceAR with RHD*D and RHD*Weak D type 4.2.2. The amino acid changes on RhceAR are such that C+c+ patient made alloanti-c. This case shows that RhceAR carries a partial c antigen and illustrates the value of DNA testing as an adjunct to hemagglutination to aid in antibody identification in unusual cases.