A recently developed and newly released Stanford-created blood test can detect Down syndrome and two other major genetic defects at early stages of pregnancy. Experts have expressed concerns, however, about the ethics of knowing a fetus’s genetics during a period of pregnancy when abortion is both safer and more commonly legal.
The $1,200 test, which analyzes fetal DNA in expectant mothers at 10 weeks, is being offered by Verinata Health — a Redwood City biotechnology company — which licensed a technique designed by Stanford biophysicist Stephen Quake.
A Verinata-sponsored clinical trial, published in the journal of the American Congress of Obstetrics and Gynecology, demonstrated the test’s effectiveness. The technique was able to predict all 89 cases of Down syndrome in 532 maternal blood samples, 35 of 36 cases of Edwards syndrome and 11 of 14 cases of Patau syndrome.
The new test offers the possibility of being able to examine fetal DNA as early as five weeks into pregnancy and to test it with just a blood drop, according to Stanford Law School professor and technology ethics expert Hank Greely ‘74.
The blood test eliminates the risk of more invasive tests such as amniocentesis, which can only be carried out later in pregnancy and create a higher risk of miscarriage. The blood test counts the millions of free-floating fetal DNA in maternal blood, detecting excessive genetic material that might signal a birth defect.
“This would not entirely replace the more invasive method of amniocentesis, but it might significantly reduce the number of mothers that undergo amniocentesis,” wrote Ahmad Salehi, a clinical associate professor in the Stanford School of Medicine, in an email to The Daily.
“This is the first step toward a real transformation to how we have babies in this country,” Greely said. “We’ve been able to do prenatal testing for over forty years but it involves difficult, expensive, unpleasant, risky procedures. This is no long needle or invasive procedure.”
“There are five million pregnancies in the world and 2 percent get genetic testing,” Greely added. “In a few years, this kind of testing will be very common.”
While testing is currently limited to Down syndrome, Edwards syndrome and Patau syndrome, the technique may be broadly applied in the future.
“Soon you will be able to look at any section of the genome you want,” Greely said. Doctors would be able to see if the fetus has Tay Sachs disease, sickle cell anemia, “if they’re a redhead, a boy or a girl.”
The test opens up “broader discussions,” according to Greely.
“We need to let parents have complete decision-making power,” he added. “It’s just better than having the government decide what you can and can’t do in pregnancy.”
“I believe the availability of rather easy techniques for prenatal detection of Down syndrome would be like a double-edged sword,” Salehi wrote. “On the one hand, it may lead to an increase in abortion rates of fetuses with Down syndrome. However, it may also open up a new window for early detection and treatment.”
“It needs to become more accurate to become diagnostic. Right now it’s recognized as screening, not as diagnostic,” added Greely. “By making it easier to test you make it easier to terminate pregnancies you don’t want. It raises some hard questions for some people.”
“Our research has shown that among more than 300 genes triplicated in Down syndrome there are a few genes that play major roles in cognitive disabilities,” Salehi wrote. “For this reason, targeting these specific genes and reducing their expression to normal in utero might be a fundamental therapy for children with Down syndrome.”