FETAL CELLS IN MATERNAL BLOOD - RECOVERY BY CHARGE FLOW SEPARATION

Fetal blood cells can be recovered from the maternal circulation by ch arge flow separation (CFS), a method that obviates the risks associate d with amniocentesis and chorionic villus sampling. By CFS, we process ed blood samples from 13 women carrying male fetuses, 2 carrying fetus es with trisomy 21, and 1 who had delivered a stillborn infant with tr isomy 18. On average more than 2000 fetal nucleated red blood cells we re recovered per 20-ml sample of maternal blood. Recovery of fetal cel ls was confirmed by fluorescence in situ hybridization with probes for chromosomes Y, 18 and 21. After culturing of CFS-processed cells, amp lification by the polymerase chain reaction revealed Y-chromosomal DNA in clones from four of six women bearing male fetuses, but not in clo nes from three women bearing female fetuses.