Elsevier

The Lancet

Volume 350, Issue 9076, 16 August 1997, Pages 485-487
The Lancet

Early Report
Presence of fetal DNA in maternal plasma and serum

https://doi.org/10.1016/S0140-6736(97)02174-0Get rights and content

Summary

Background

The potential use of plasma and serum for molecular diagnosis has generated interest. Tumour DNA has been found in the plasma and serum of cancer patients, and molecular analysis has been done on this material. We investigated the equivalent condition in pregnancy—that is, whether fetal DNA is present in maternal plasma and serum.

Methods

We used a rapid-boiling method to extract DNA from plasma and serum. DNA from plasma, serum, and nucleated blood cells from 43 pregnant women underwent a sensitive Y-PCR assay to detect circulating male fetal DNA from women bearing male fetuses.

Findings

Fetus-derived Y sequences were detected in 24 (80%) of the 30 maternal plasma samples, and in 21 (70%) of the 30 maternal serum samples, from women bearing male fetuses. These results were obtained with only 10 μL of the samples. When DNA from nucleated blood cells extracted from a similar volume of blood was used, only five (17%) of the 30 samples gave a positive Y signal. None of the 13 women bearing female fetuses, and none of the ten non-pregnant control women, had positive results for plasma, serum or nucleated blood cells.

Interpretation

Our finding of circulating fetal DNA in maternal plasma may have implications for non-invasive prenatal diagnosis, and for improving our understanding of the fetomaternal relationship.

Introduction

The passage of nucleated cells between mother and fetus is well recognised.1, 2 One important clinical application is the use of fetal cells in maternal blood for non-invasive prenatal diagnosis.3 This approach avoids the risks associated with conventional invasive techniques, such as amniocentesis and chorionic-villus sampling. Substantial advances have been made in the enrichment and isolation of fetal cells for analysis.3, 4 However, most techniques are time-consuming or require expensive equipment.

There has been much interest in the use of DNA derived from plasma or serum for molecular diagnosis.5 In particular, there have been reports that tumour DNA can be detected by molecular techniques in the plasma or serum of cancer patients.6, 7, 8 Such reports prompted us to investigate whether fetal DNA can be detected in maternal plasma and serum.

Section snippets

Patients

Pregnant women attending the John Radcliffe Hospital (Oxford, UK) were recruited before amniocentesis or delivery. We obtained approval of the project from the Central Oxfordshire Research Ethics Committee. Informed consent was obtained in each case. 5–10 mL maternal peripheral blood was collected into one tube containing edetic acid and one plain tube. For women undergoing amniocentesis, maternal blood was always taken before the procedure, and 10 mL amniotic fluid was also collected for fetal

Results

Serial dilutions of male genomic DNA in 1 μg female genomic DNA were carried out and amplified by the Y-PCR system with 60 cycles of amplification. Positive signals were detected up to the 1/100 000 dilution—ie, the approximate equivalent of a single male cell.

The optimum volume of heated plasma and serum samples for PCR amplification was assessed by subjecting 1 μL, 2 μL, 10 μL, 30 μL, and 50 μL heated plasma or serum samples from male individuals to Y-PCR. The best signal was obtained from 10

Discussion

Our results show that fetal DNA is present in maternal plasma and serum. Use of maternal plasma or serum for the detection of fetal DNA for non-invasive prenatal diagnosis may therefore be possible. Ironically, plasma is the material routinely discarded in the early stages of many DNA-extraction protocols, and also after the density-centifugaton step used by many investigators for non-invasive prenatal diagnosis. This is probably one of the reasons why the presence of fetal DNA in maternal

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