Assay of Rh30 exons in the Rh_null family by PCR and restriction analysis. Individual exons were amplified by PCR and their gene origin was determined by unique restriction site or primer specificity.29 The digested PCR products were separated by native 6% PAGE and stained with ethidium bromide. Enzymes used and exon numbers are indicated above gel panels. Lanes 1 through 6 are as in Fig 1. Below each panel, the size and gene origin of the respective fragments are shown (“+” indicates a cleavage). In the exon 10 panel, the expected RhD (233 bp) and RhCe (163 bp) bands were from coamplification of both gene fragments using a common 5′ primer, Ex-10s, coupled with two 3′-UTa primers (Table 1). Exons 3 and 8 were not analyzed, because the former lacks the unique site and the latter is identical between RhCE and RhD.6-10