RHD and RHCE diversity in 226 patients with SCD.RH alleles identified in patients with SCD. Each gray box represents 1 of 10 exons in the RH genes. Black boxes represent exon exchange between RHD and RHCE. Vertical black lines indicate position in the exon encoding amino acid substitutions in the protein. Dashed lines indicate gene deletion. Arrowhead indicates 37-bp duplication. Hatched boxes represent exons encoding a frameshift and untranslated region of the inactive RHD pseudogene.