RHD and RHCE diversity in 320 patients with SCD.RH alleles identified in patients with SCD. Each grey box represents 1 of 10 exons in the RH genes. Black boxes represent exon exchange between RHD and RHCE. Vertical black lines indicate positions encoding amino acid substitutions in the protein. Dashed line indicates RHD gene deletion. Arrowhead indicates the 37-bp duplication. Hatched boxes represent exons encoding a frameshift and untranslated region of the inactive RHD pseudogene.