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 trophoblast cells in maternal peripheral blood for noninvasive prenatal diagnosis of numeric chromosomal aberrations.

STUDY

DESIGN

A combined procedure for immunocytochemical identification and deoxyribonucleic acid fluorescence in situ hybridization was used after a single enrichment step consisting of density gradient centrifugation. A specific HLA-G monoclonal antibody was used in combination with X and Y chromosome specific probes in deoxyribonucleic acid fluorescence in situ hybridization to confirm fetal identity of cells bearing HLA-G in the case of a male fetus.

RESULTS

We detected fetal trophoblast cells expressing HLA-G in maternal blood starting at 9 weeks' gestation. In addition to fetal sex prediction with X and Y chromosome-specific probes, fetal aneuploidy was confirmed in peripheral blood from a pregnancy complicated by trisomy 21.

CONCLUSION

Although the numbers of fetal cells were extremely low, the proof of concept was demonstrated. Early noninvasive prenatal screening for numeric chromosomal abnormalities with fetal trophoblast cells is feasible.