Lack of RH C/E expression in the Rhesus D--phenotype is the result of a gene deletion.

We have investigated the arrangement of genes in the rare Rh (Rhesus) partial null condition D--. Southern blot and PCR studies under conditions which distinguish the highly homologous RH D and RH C/E genes show that in an Icelandic family with the D-- haplotype at least 85% of the RH C/E gene is deleted. This finding is in contrast to one other published case of this phenotype, where intact RH D and C/E genes were found, and also to the full amorph Rhnull phenotype, where an intact RH C/E gene was found, accompanied by the deletion of the RH D gene typical of Rh D-negative individuals.