Gross structure of RH50 and RH30 in Rh_null as determined by Southern blots. (A) Southern blot analysis of the genes encoding the Rh50 and Rh30 proteins. Lane 1, RhD-positive; lane 2, RhD-negative; and lane 3, Rh_null(YT). The BamHI and Sph I blots were probed with the full-length Rh50 cDNA and Rh30 cDNA (exon 4-7), respectively. Size markers (in kb) of Hind III-cleaved lambda phage DNA are shown at the left margin. (B) Schematic representation of the proband’s genotype for RH50 and RH30, whose chromosomal location is indicated. Note that the proband is homozygous for the two tightly linked and actively expressed Rh30 genes, RHD and RHCe. However, the two Rh50 alleles carry different, subtle changes as suppressor mutations (indicated by crosses).