Development of noninvasive fetal DNA diagnosis from nucleated erythrocytes circulating in maternal blood

Abstract

A considerable effort is being spent in developing noninvasive prenatal DNA diagnostic procedures. We recently reported that nucleated erythrocytes (NRBCs) can be enriched from maternal blood by a galactose-specific lectin method. In the present study, to prove that fetal NRBCs are definitely present in maternal blood and are a good source for fetal genetic diagnosis, we evaluated methods for lectin enrichment and subsequent fluorescence in situ hybridization (FISH) analysis through fetal gender determination. Peripheral blood samples were collected from pregnant women (median 15, range: 10-18 weeks). From the blood samples, NRBCs were enriched based on galactose-specific lectin method. After detecting them by their morphology, NRBCs are separated and taken in a new glass slide by micromanipulator. We analyzed fetal gender using X and Y-chromosome-specific FISH probes. The results were compared with fetal gender analysis using Y-chromosomal sequences in maternal plasma. The fetal gender analyses by FISH in 20 pregnant women were all in accordance with the results from maternal plasma analyses. It is confirmed that fetal NRBCs were present in maternal blood and that 30.4% of NRBCs in maternal blood were fetal in origin. We have successfully carried out a noninvasive prenatal DNA diagnosis of fetal gender by using galactose-specific lectin method and subsequent FISH analysis.