Partial expression of RHc on the RHD polypeptide

BACKGROUND: In the human Rh blood group system, c is, after D, the most imm unogenic antigen. STUDY DESIGN AND METHODS: The background of a new partial c phenotype (D-c) , identified on the RBCs of two unrelated white persons, was studied. This was done by analyzing the reactivity of the RBCs from the donors with anti- c reagents, by performing sequence analysis, and by carrying out transducti on studies. RESULTS: Serologic results suggested the existence of a new partial c pheno type. Genomic DNA and cDNA analysis revealed a normal RHCe allele, a normal RHD allele, and an RHD allele that carried two point mutations: 307T >C an d 329T >C (the latter known to be associated with the DVII, Tar-positive ph enotype). No normal RHc allele was found. Thus, it was most likely that c i s encoded by the mutated RHD allele (phenotype DD(c)CCee). Indeed, subseque nt transduction of K562 erythroleukemic cells with an RHD cDNA carrying the 307T>C point mutation (leading to S103P) resulted in the expression of c. CONCLUSION: In the human Rh system, P103 is involved in the expression of c . Moreover, c can be expressed in vivo on the D polypeptide.