Detection of fetal Rhesus D and sex using fetal DNA from maternal plasma by multiplex polymerase chain reaction

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.