Blood test can find thousands of genetic conditions in pregnancy, say scientists | Pregnancy

A new non-invasive foetal sequencing (NIFS) blood test can detect thousands of serious genetic conditions in a developing foetus, according to scientists. Presented at the European Society for Human Genetics conference in Gothenburg, the test identifies DNA fragments in the mother’s bloodstream, potentially reducing the need for invasive procedures like amniocentesis.

The technique uses advanced sequencing to identify genetic conditions, including cystic fibrosis, that usually require invasive diagnosis. Dr. Christopher Whelan, a senior computational scientist at the Broad Institute of Massachusetts Institute of Technology and Harvard University, stated the test can detect the majority of conditions on major newborn sequencing and foetal anomaly panels.

Whelan noted the test covers the over 2,500-gene Genomics England foetal anomalies panel. Validation studies identified rare genetic disorders such as achondroplasia, Stickler syndrome, Charge syndrome, and Noonan syndrome.

How does NIFS compare to invasive screening?

Current non-invasive blood tests are generally limited to a small number of conditions, such as Down’s syndrome. NIFS expands this capacity to nearly all genetic conditions found on newborn screenings, according to the researchers.

Researchers tested NIFS on 565 pregnancies at an average gestation of 17 weeks. By sequencing fragments of DNA across nearly 23,000 genes, the test identified 95-99% of the genetic variants found by invasive methods and more than 97% of clinically relevant variants.

Whelan said the test could serve as a frontline tool for pregnancies where ultrasounds or other screenings show an anomaly. He noted that many women currently refuse amniocentesis or chorionic villus sampling (CVS) due to cost, access, stress, and the risk to the foetus.

What are the implications for reproductive medicine?

Prof Alexandre Reymond of the University of Lausanne described the ability to sequence a foetal genome without a direct sample as a “tour de force.” He stated that the development opens treatment and prevention opportunities that could change reproductive medicine forever.

Prof Angus Clarke, a clinical geneticist at Cardiff University, called the work a “very impressive technical feat.” He noted it would be particularly useful when a genetic condition is suspected and prenatal treatment could be initiated.

However, Clarke warned that exploratory screening could identify genes of unknown significance. This may cause significant anxiety for parents and could potentially lead to unnecessary medicalisation and surveillance for infants.

What happens next for the NIFS test?

The test may be adopted as a safer alternative to invasive sequencing if it is confirmed as reliable. It could potentially reduce the reliance on needles used to collect amniotic fluid.

Medical providers may use the test to change how pregnancy, delivery, or newborn care is managed for those with rare genetic disorders. However, the implementation of the test may require guidelines to manage “potential answers” that arise when no specific problem is being sought, according to Clarke.

Frequently Asked Questions

What is non-invasive foetal sequencing (NIFS)?
It is a blood test that detects tiny fragments of a foetus’s DNA circulating in the mother’s bloodstream to identify thousands of serious genetic conditions.

How accurate is NIFS compared to invasive tests?
In a study of 565 pregnancies, NIFS picked up 95-99% of the genetic variants found by amniocentesis or chorionic villus sampling and over 97% of clinically relevant variants.

What are the risks of traditional invasive testing?
Amniocentesis involves using a thin needle to collect amniotic fluid and can lead to miscarriage in approximately one in 200 pregnancies.

Would you prefer a non-invasive test that provides more data, even if some of that data is of unknown significance?