Explosion of Prenatal Genetic Testing on Horizon, Greely Says
Game-changing advancements in prenatal genetic testing will soon force society to confront a host of difficult ethical, practical and legal questions, a law and biomedicine expert said at the Law School last week.
“I think within the next five, and almost certainly 10 years, we will see an enormous expansion of prenatal fetal genetic testing in this country,” said Stanford law professor Hank Greely, who delivered the Sadie Lewis Webb Lecture in Law and Biomedicine.
Greely said new technology will make it possible to easily and cheaply check millions of fetuses for genetic disorders ranging from Down syndrome to cystic fibrosis, and will likely lead to a significant increase in terminated pregnancies.
Despite a drastic increase in understanding of genetics, only about 60,000 fetal genetic tests are currently done each year. That's down from 100,000 a decade ago and 120,000 tests per year 20 years ago, Greely said.
The development of other methods to check for Down syndrome has contributed to the decrease in fetal genetic testing, which currently requires an invasive, uncomfortable procedure that substantially increases the chance of a miscarriage, he said.
“So where’s the beef?” Greely said. “I think we’re about to find out.”
Researchers have discovered that a certain amount of fetal DNA exists in a mother’s blood stream. As the cost of genetic sequencing declines, doctors will be able to cheaply and easily identify fetal DNA within the mother’s bloodstream and test it for genetic disorders, Greely said.
Such tests could be done early in a pregnancy, and within a few years could cost as little as $1,000, be covered by insurance and require nothing more than a blood — or even urine — sample from the mother.
“No big long needle, no surgical procedure, no risk of miscarriage, no new procedure at all,” Greely said.
Currently, there are about 5,500 children born each year with Down syndrome, and about 1,500 children born with similar, but more serious, chromosomal genetic disorders, he said. There are also 15,000 to 20,000 children born with other genetic disorders such as cystic fibrosis, Greely said.
The new tests would be able to screen for all of these things, and potentially even other traits.
“One that sticks out like a sore thumb is sex. It’s pretty easy to find out if there’s a piece of Y chromosome in that maternal serum,” Greely said.
With time, these tests could even predict for things like eye color, skin tone, hair color, baldness and likely height, he said.
"If it’s FDA approved, I believe every obstetrician in the country will quickly decide he or she has to offer it to every pregnant woman, because of legal standard of care issues,” Greely said. If Medicaid — which pays for about 40 percent of the births in the country — covers the test, it could be performed in as many as three million out of approximately five million pregnancies in the country each year, even accounting for women who opt not to have it, he said.
This could lead to a sharp rise in terminations. The new test can be done only five weeks into a pregnancy, when it is still possible to terminate through chemical — not surgical — means, Greely said.
“There will be more terminations. Of women who get terrible, terrible news about their pregnancy, their fetus, some will choose to terminate their pregnancy.”
Currently, about 85 percent of pregnant women whose fetus is diagnosed with Down syndrome choose to terminate the pregnancy, Greely said. He said he doesn’t believe the percentage will be as high with the new test, but said it will still lead to a substantial increase in terminations.
“We may see a great decline in the number of children born every year with Down syndrome or the number of children born every year with sickle cell,” he said.
The new technology could lead to a host of practical and legal questions.
Currently, pregnant women who undergo fetal genetic testing are paired with a genetic counselor. There are about 2,300 genetic counselors in the country, as well as 1,000 clinical geneticists.
“They cover 60,000 prenatal tests. Who’s going to do 2 to 3 million prenatal tests? Who is going to do that counseling? We don’t have enough trained people to do it, even if that’s all they ever did,” Greely said.
Another potential issue has to do with the identification of genetic disorders in the mother herself, or even in the father or other relatives.
“You’re getting genetic information about the fetus, you’re also getting complete genetic information with respect to those pieces you are looking for, on the mother. Did she sign up to have her genome tested? What happens if you discover from the mother that she’s got something she should worry about?”
The likely increase in abortions could also lead to tricky legal questions, he said.
“If we wanted to regulate this, could we, constitutionally? Could we say you can’t terminate a pregnancy for reasons of sex or hair color or eye color? By the way, I think [such terminations] would be unlikely, but it’s a big country and somebody will do it. Somebody will certainly do it for sex. It already happens, [though] not very often in the U.S., compared to other countries.”
Even if the government were to forbid such terminations, the technology could lead to reproductive tourism, where people with the means would simply travel to countries with less strict restrictions, he said.
“Maybe we could prevent it. Maybe we couldn’t. We certainly couldn’t prevent it perfectly, which means then that you are preventing it for everybody except those who are rich enough to go elsewhere or unethical enough to work around the laws, which may not exactly be the people you most want to be able to have genetic testing,” Greely said.
And there remains the larger issue of whether a government could and should make these decisions, he said.
“Do we really want to intrude on these decisions? On the other hand do we really want people terminating pregnancies because of hair color or eye color, or diseases that may strike somebody 70 years from now, or may not, and may well be cured during that 70 years?”
Greely said he believes the answers will likely be different in each country, but that he thinks every modern society will have to address them.
“What do we as a society want? I don’t have a clue about how we will end up answering that question.”