Alloimmunization and genotype-predicted Rh antigen expression among chronically transfused patients with SCD receiving prophylactic C, E, and Kmatched red cells by simple transfusion. (A) Antibody specificities detected among 48 chronically transfused patients with SCD. Columns for each specificity indicate patients’ corresponding antigen status (positive or negative) as reported by standard serologic or genotyping methods. (B) RHD and RHCE genotype-predicted Rh antigen expression among patients with SCD. Partial antigens predicted from genotypes with variant alleles that result in Rh epitope(s) missing and absence of conventional antigen. RHD*DAU0 or RHCE*ce48C has not been shown to encode Rh proteins lacking epitopes and is considered altered antigens.