New Maternal Blood Test Could Transform Prenatal Screening
A new blood test for mothers that detects a range of serious genetic disorders in developing fetuses might reduce the need for invasive procedures during pregnancy, according to researchers.
This innovative test will be presented at the European Society for Human Genetics conference in Gothenburg. It works by identifying tiny pieces of fetal DNA that circulate in the mother’s blood. By employing advanced sequencing methods, scientists can recognize a significant number of genetic conditions—like cystic fibrosis—that are usually diagnosed only via invasive tests such as amniocentesis.
Known as non-invasive fetal sequencing (NIFS), this method could serve as a safer and equally effective screening option for all pregnancies, notes Dr. Christopher Whelan, a senior computational scientist affiliated with the Broad Institute of MIT and Harvard.
“This test is capable of detecting thousands of serious genetic conditions, including most of those included on major newborn sequencing and fetal anomaly panels, such as the extensive 2,500-gene panel from Genomics England,” he explains.
In their validation study, the researchers identified conditions like Noonan syndrome, Charge syndrome, Stickler syndrome, and achondroplasia, among various rare genetic disorders—many of which benefit from early diagnosis during pregnancy, delivery, or newborn care.
Current non-invasive blood tests based on fetal DNA have already made significant strides in prenatal diagnostics, but their applications have remained limited to a few conditions, such as Down syndrome. If proven reliable, this latest test could significantly broaden the scope to cover nearly all genetic disorders included in newborn screenings.
Dr. Whelan envisions this as a primary test for cases where an ultrasound or another screening indicates an anomaly. “Right now, many women opt out of invasive tests like amniocentesis and chorionic villus sampling due to the associated risks to the fetus, stress, accessibility issues, and costs, even though those tests are highly accurate,” he adds.
Amniocentesis, for context, involves using a thin needle to extract amniotic fluid and is generally performed between the 15th and 20th weeks of gestation. Although it’s quite reliable, it carries a miscarriage risk of about one in 200 pregnancies.
The researchers conducted tests on 565 pregnancies, averaging 17 weeks along. By sequencing small DNA fragments and employing advanced computational techniques, they identified genetic variations across nearly 23,000 genes for each fetus. Their findings aligned closely with results from either amniocentesis or CVS, revealing that their test detected 95-99% of variants found in invasive methods and over 97% of clinically significant variants.
Prof. Alexandre Reymond from the University of Lausanne, who wasn’t part of the research, described the ability to sequence a fetus’s entire genome without direct sampling as exceptional. “This fundamentally alters the landscape of reproductive medicine, opening up new avenues for treatment and prevention,” he remarked.
Meanwhile, Prof. Angus Clarke, a clinical geneticist at Cardiff University, called the work a remarkable technical achievement. He noted that it would prove especially useful in scenarios where a genetic condition is suspected so that prenatal treatment could be initiated.
However, he also cautioned that using this test for broad screening might uncover genes of uncertain significance, leading to unnecessary anxiety for parents. “It’s a tricky situation. When you’re not searching for a specific problem, generating potential concerns can result in more stress than relief,” he said.
