Breakthrough Blood Test Detects Thousands of Genetic Conditions in Pregnancy

The New Blood Test

A new maternal blood test that can detect thousands of serious genetic conditions in the developing foetus could limit the need for invasive screening during pregnancy, according to scientists.

How the Test Works

The test, known as non-invasive foetal sequencing (NIFS), relies on detecting tiny fragments of a foetus’s DNA that circulate in the mother’s bloodstream during pregnancy. Using advanced sequencing techniques, scientists were able to identify a very high proportion of genetic conditions, such as cystic fibrosis, that are currently only reliably diagnosed using amniocentesis or other invasive tests.

The Data Analysis

The researchers tested NIFS on 565 pregnancies at an average of 17 weeks of gestation. By sequencing the small fragments of DNA and using advanced computing methods, they were able to identify genetic variants across nearly 23,000 genes in each foetus. Checking their findings against those from either amniocentesis or CVS, they found that their test picked up 95-99% of the genetic variants found by the invasive methods and more than 97% of clinically relevant variants.

The Impact Analysis

The new technique could be used as a safer, equally accurate screening tool in all pregnancies, according to Dr Christopher Whelan, a senior computational scientist at the Broad Institute of Massachusetts Institute of Technology and Harvard University. “This test is capable of detecting thousands of serious genetic conditions, including the majority of the conditions that appear on the major newborn sequencing and foetal anomaly panels, such as the over 2,500-gene Genomics England foetal anomalies panel,” he said.

The Prediction

Prof Alexandre Reymond of the University of Lausanne, who was not involved in the research, said: “Sequencing the entire genome of a foetus without even getting a sample from that foetus is a tour de force. It immediately opens up treatment and prevention opportunities and means that reproductive medicine will be changed for ever.” However, Prof Angus Clarke, a clinical geneticist at Cardiff University, warned that using the test for exploratory screening could turn up genes of unknown significance, causing huge anxiety for parents and potentially placing babies on an unnecessary path of surveillance and medicalisation.