An unusual Rhesus haplotype, --D--, in Iceland.

Two female patients are described who were, following difficulties in blood cross matching, found to be homozygous for the rare Rhesus --D-- gene complex. Both patients had formed Rh antibodies, one provoked by transfusions and the other by three pregnancies. The parents' relationship of one could easily be traced. Family tracing of the other patient was unsuccessful but her parents were probably related. The frequency of the --D-- haplotype in Icelanders was estimated 1/214 by investigating 750 families of disputed paternity.