Objective: To test the sensitivity, specificity and reproducibility using fetal DNA obtained from plasma of pregnant women by polymerase chain reaction for the simultaneous detection of both fetal sex and Rhesus D genotype.
Method: Blood samples were obtained from 22 Rhesus D negative pregnant women about to undergo an invasive procedure. DNA was extracted from the plasma fraction and analysed by a multiplex nested polymerase chain reaction using Y chromosome-and Rhesus D-specific primers. The results of this experimental procedure were compared with those obtained from the analysis performed on material gained by the invasive procedure.
Results: The sensitivity of the plasma polymerase chain reaction-based method was surprisingly high, with both fetal genotypes being correctly determined in almost 100% of the cases examined. In only one instance was a false positive result for the detection of Rhesus D recorded, which on subsequent analysis was negative.
Conclusions: The ease and rapidity with which the plasma polymerase chain reaction-based method can be performed makes it a promising method for the analysis of multiple fetal loci, such as Rhesus D and sex.