New Insights Into Fetal DNA Could Improve Non-Invasive Prenatal Testing

Although it offers a safer alternative to invasive procedures such as amniocentesis, high-risk results still require confirmatory testing and can produce false alarms. Researchers now present new insights into how fetal DNA circulates in maternal blood, which could support improvements in prenatal screening.

Researchers at Adelaide University led an international review of decades of research on fetal DNA in maternal circulation. The work focuses on non-invasive prenatal testing (NIPT), which analyzes small DNA fragments from the placenta that circulate in the mother’s bloodstream. Since its introduction in 2011, millions of women worldwide have used NIPT, and about 30% of families in Australia choose to pay around A$500 for the test, often out of pocket.

The researchers highlight that NIPT still has important limitations despite its widespread adoption. If NIPT indicates high risk for a chromosomal condition, parents may wait more than a month for confirmation and undergo an invasive diagnostic procedure. High-risk NIPT results are rare, but 47% of such results are described as false alarms.

To better understand how fetal DNA moves through maternal blood, the researchers examined its origins, how it enters the bloodstream, and what structures may carry it once it is circulating. They challenged long-held assumptions about fetal DNA and highlighted unresolved questions about the exact placental cell types that release it. They also considered whether fetal DNA travels attached to extracellular vesicles or other molecular structures.

The paper, titled “Reappraising the topology of cell-free fetal DNA in maternal blood towards improved prenatal genetic diagnostics,” was published in Science Advances. The collaborating team was led by Adelaide University and included the Future Industries Institute. The researchers concluded that understanding the origin and structure of fetal DNA could help increase the fetal fraction available for testing, which they identify as a major challenge for current prenatal screening technologies.

“Science and technology have advanced rapidly, but our biological understanding of fetal DNA has not kept pace. By uncovering the fundamental biology of fetal DNA, we can create new tools that make prenatal testing more reliable, more comprehensive and potentially more affordable,” said Professor Benjamin Thierry, Director of the Precision Nanomedicine Program at Adelaide University.

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