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Circulating fetal DNA: its origin and diagnostic potential-a review
1Division of Genetics, Departments of Pediatrics, Obstetrics and Gynecology, Tufts-New England Medical Center and Tufts University School of Medicine, Box 394, 750 Washington Street, Boston, MA 02111, USA. Dbianchi@tufts-nemc.org
Placenta
|March 23, 2004
Summary
Abnormal trafficking of fetal nucleic acids in maternal blood is linked to placental pathology and fetal conditions like trisomy. This research highlights potential for new non-invasive prenatal screening tests.
Area of Science:
- Obstetrics and Gynecology
- Molecular Biology
- Genetics
Background:
- The placenta is not an impermeable barrier; fetal cells and cell-free nucleic acids circulate in maternal blood.
- Pregnancy complications (e.g., pre-eclampsia) and fetal abnormalities (e.g., trisomy 21) increase fetal nucleic acid transfer to the mother.
Purpose of the Study:
- To demonstrate the association between abnormal feto-maternal nucleic acid trafficking and fetal/placental pathology.
- To explore the potential for novel non-invasive diagnostic and screening tests based on these findings.
Main Methods:
- Quantitative PCR amplification of the Y-chromosome specific gene DYS1 to measure male fetal DNA levels.
- Analysis of serum or plasma samples from pregnant women in case-control sets.
- Development of gestation-specific normal values and theoretical models using DYS1 as a fetal DNA marker.
Main Results:
- Elevated fetal DNA levels were observed in pregnancies with trisomies 21 and 13 (but not 18).
- Pre-eclampsia development was preceded by a characteristic bi-phasic elevation of cell-free fetal DNA.
- The placenta is identified as the primary source of circulating fetal nucleic acids, with some contribution from apoptotic hematopoietic cells.
Conclusions:
- Elevated fetal cell-free DNA is indicative of placental pathology.
- Clinical application requires a reliable gender-independent marker (e.g., DNA polymorphisms, epigenetic markers, mRNA).
- Fetal cell-free nucleic acids offer potential for non-invasive monitoring of placental health.