Schematic structure of the RH gene locus.

(A) The positions and orientations of the genes and the Rhesus boxes are indicated by open arrows and triangles, respectively. The exons are shown as vertical bars, and their exon numbers are indicated. The 2 RH genes have opposite orientation, face each other with their 3′ ends, and are separated by about 30 000 bp. A third gene, SMP1, has the same orientation as RHD and is positioned between RHD and RHCE. The RHDgene is flanked on both sides by the 2 highly homologous Rhesus boxes, which are noted by (b). All exons are shorter than 200 bp, with the exception of the RHD and SMP13′ terminal exons. (B) Data used to establish this structure include the extension of genomic sequences represented in cDNA (horizontal arrows) and identities and homologies to genomic clones as noted: bar a, identity with dJ465N24; bar b, homology of RHD to dJ469D22; bar c, homology of RHD 3′ part to dJ465N24; and bar d, identity with dJ469D22. The positions of 3 bridging PCR reactions are indicated. The correct position of a nucleotide stretch previously reported by Okuda et al9 as a “spacer” sequence between RHD and RHCE is indicated by the bar labeled with the letter “s.”