HLA-G expression in trophoblast cells circulating in maternal peripheral blood during early pregnancy

OBJECTIVE: The aim of this study was to assess the use of circulating troph oblast cells in maternal peripheral blood for noninvasive prenatal diagnosi s of numeric chromosomal aberrations. STUDY DESIGN: A combined procedure for immunocytochemical identification an d deoxyribonucleic acid fluorescence in situ hybridization was used after a single enrichment step consisting of density gradient centrifugation. A sp ecific HLA-G monoclonal antibody was used in combination with X and Y chrom osome-specific probes in deoxyribonucleic acid fluorescence in situ hybridi zation to confirm fetal identity of cells bearing HLA-G in the case of a ma le fetus. RESULTS: We detected fetal trophoblast cells expressing HLA-G in maternal b lood starling at 9 weeks' gestation; In addition to fetal sex prediction wi th X and Y chromosome-specific probes, fetal aneuploidy was confirmed in pe ripheral blood from a pregnancy complicated by trisomy 21. CONCLUSION: Although the numbers of fetal cells were extremely low, the pro of of concept was demonstrated. Early noninvasive prenatal screening for nu meric chromosomal abnormalities with fetal trophoblast cells is feasible.