Polymerase chain reaction determination of RhD blood type: an evaluation of accuracy

To evaluate the accuracy of polymerase chain reaction (PCR) amplification of a portion of the RhD gene by testing a large number of DNA samples derived from individuals whose RhD status was established by the standard serologic method.

Seven hundred sixty-five samples were obtained from two sources: subjects taking part in studies at the University of Iowa Hospitals and Clinics (n = 107), and Centre d'Etude du Polymorphisme Humain (CEPH) families used for studies of genetic variation (n = 658). Deoxyribonucleic acid was extracted from blood samples of University of Iowa volunteers and from CEPH families by standard techniques. With few modifications, published primers, reaction and electrophoresis conditions, which yield a 1200-bp fragment in all individuals and a 600-bp fragment in RhD-positive individuals, were used.

By standard serologic techniques, we identified samples from 632 RhD-positive and 133 RhD-negative individuals. Two (both from CEPH) of the 632 RhD-positive individuals were characterized as RhD-negative by PCR. Seven of the 133 RhD-negative samples were judged to be RhD-positive by PCR because of the presence of a light 600-bp band. Despite repeated attempts, no bands or DNA were identified in one RhD-negative sample. Thus, the sensitivity of RhD typing by PCR was 99.7%, the specificity 94.0%.

Based on our data, it would appear that the use of PCR to establish RhD type can be introduced cautiously into current management schemes in the evaluation of RhD sensitization.