ISOLATING FETAL CELLS IN MATERNAL CIRCULATION FOR PRENATAL-DIAGNOSIS

Fetal cells unequivocally exist in and can be isolated from maternal b lood. Erythroblasts, trophoblasts, granulocytes and lymphocytes have a ll been isolated by various density gradient and flow sorting techniqu es. Chromosomal abnormalities detected on isolated fetal cells include trisomy 21, trisomy 18, Klinefelter syndrome (47,XXY) and 47,XYY. Pol ymerase chain reaction (PCR) technology has enabled the detection of f etal sex, Mendelian disorders (e.g. beta-globin mutations), HLA polymo rphisms, and fetal Rhesus (D) blood type. The fetal cell type that has generated the most success is the nucleated erythrocyte; however, tro phoblasts, lymphocytes and granulocytes are also considered to be pres ent in maternal blood. Fetal cells circulate in maternal blood during the first and second trimesters, and their detection is probably not a ffected by Rh or ABO maternal-fetal incompatibilities. Emphasis is now directed toward determining the most practical and efficacious manner for this technique to be applied to prenatal genetic diagnosis. Only upon completion of clinical evaluations could it be considered appropr iate to offer this technology as an alternative to conventional invasi ve and non-invasive methods of prenatal cytogenetic diagnosis.