Known RhD and RhCE gene DNA sequence differences in exons 7 and 10 of these genes are used to determine the RhD status of CVS, amniocyte, or blood samples by direct DNA-based testing. Two distinct regions of the RhD and RhCE genes are evaluated in order to detect known rare RhD-positive gene structure variants.
Testing requires only 1-2 ml of amniotic fluid (5 mg of chorionic villi) and 5-7 ml of maternal blood in EDTA shipped by overnight courier. Results will sent out by FAX the next working day.
In the example shown below, lane 1 shows a no DNA control, lanes 2 and 3 show RhD-positive and RhD-negative controls, respectively, and lane 4 shows a Rh-D negative fetal amniocyte sample .