In the past, a risky amniocentesis was needed to detect if a fetus had Down syndrome. Today, all it takes is a blood test of the mom. (Getty Images)
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A new, simple way to detect Down syndrome in a fetus means the condition will be virtually extinct — but not without a great deal of controversy, experts say.
Last month, San Diego-based Sequenom released a test that allows doctors to screen for the most prevalent type of Down syndrome with only a blood test from the mother. The screening is available in 20 cities and is expected to hit New York soon. Two other companies have plans to release similar tests next year.
“What you end up having is a world without people with Down syndrome,” says Paul Root Wolpe, director of the center for ethics at Emory University. “And the question becomes is that a good thing or bad thing?”
Because the current methods of screening for Down syndrome, amniocentesis and chorionic villus sampling, carry a risk of inducing miscarriage, only about 2% of pregnant women in the nation undergo the screening, says Dr. Brian Skotko, of the Down syndrome program at Children’s Hospital Boston.
The safer prenatal screenings will likely mean more women will be tested, and the number of women carrying babies with Down syndrome who terminate their pregnancies could increase, if not skyrocket. Today, 92% of mothers who get a definitive diagnosis of Down choose to abort, surveys show.
“It’s a real conundrum,” Wolpe says. “Human beings have always tried to fight and cure disease, and this tool, projecting it forward 50 years when it’s powerful enough, will make a difference in eliminating those diseases in the world. It’s a tough call.”
People with Down syndrome typically have an extra copy of one of their chromosomes, usually chromosome 21, which changes their body and brain’s development and causes mental and physical problems such as mild to moderate mental retardation and unusual facial characteristics.
Older women are at an increased risk of carrying a baby with Down syndrome — a 20-year-old woman has a 1 in 1,667 chance of having a baby with Down syndrome; but her risk jumps to 1 in 30 by the time she’s 45. Skotko says that because more older women are having babies than ever before, the percentage of babies born with Down syndrome should have risen 42% between 1989 and 2006. Instead, the number has decreased by 11% during that time, largely due to elective termination.
Today, about 6,000 babies with Down syndrome are born each year, according to the National Down Syndrome Society — and 80% are born to women under the age of 35.
Amniocentesis testing requires a sample of amniotic fluid. During CVS, doctors remove a small piece of tissue from the placenta for analysis. Both tests put mothers at risk for miscarriage.
But Sequenom’s test, called MaterniT21, analyzes fetal DNA from a sample of the mother’s blood to test for the most common form of Down syndrome. In a study published last month in Genetics in Medicine, MaterniT21 detected 98.6% of Down syndrome cases.
Pregnant women typically undergo preliminary screenings, such as an ultrasound, to determine whether more invasive tests are needed. Sequenom says its new test is designed for the 750,000 women a year who are deemed to be at high risk after those less-invasive screenings. MaterniT21 likely won’t replace amniocentesis right away, but women who test negative with the new blood test might feel confident enough to skip the more-invasive procedures.
Critics point out that the new test doesn’t detect other chromosomal abnormalities, including some rare forms of Down syndrome, that do get picked up through CVS and amniocentesis. The screening is not yet available in New York because the state has its own approval process.
Still, it’s likely to make testing for Down syndrome common for almost all expectant mothers.
“Now women are able to get nearly 100% accurate results without the risk of miscarriage,” Skotko says.
Skotko and others believe that safer screenings could lead younger women to be screened — and to face tough decisions.
When Louise Borke was pregnant 22 years ago, at the age of 34, doctors considered the risk of miscarriage from amniocentesis to be higher than the risk that a woman her age would have a baby with Down syndrome. So she was not screened and did not know her son would be born with the congenital disorder.
Borke’s son, Louis Sciuto, volunteers regularly at a Boston-area food bank near his home. He has a job at Target. He has friends and a rich life. Borke says she truly can’t say what she would have done had she known about her son’s condition while she was still pregnant, but she knows that the world is a better place for having him in it.
“People with Down syndrome are not charity cases,” she says. “They are contributing members of society.”
While the technology for detecting Down syndrome has grown more sophisticated, Borke worries that the public image of the chromosomal abnormality has not. Too many people associate Down syndrome with the images of institutionalized kids from 30 years ago.
A number of organizations, including the National Society of Genetic Counselors and the National Down Syndrome Congress worked together on a pamphlet, “Understanding a Down Syndrome Diagnosis,” with more up-to-date information about the condition. Borke is working with several organizations to urge Sequenom and other companies to give women this information along with their diagnoses.
“The images depicted previously were of lethargic, heavy people in unattractive clothes with their eyes half-closed and their tongues hanging out,” Borke says. “It’s not the images you see today of babies and children dressed in cute clothes smiling and laughing with their friends,” she says. “It’s a different reality today than the reality when people were routinely institutionalized.”
Thirty years ago, the life expectancy of someone with Down syndrome was 25. Today it is 55. While there is no cure for Down syndrome, surgeries to correct or improve the heart conditions, gastrointestinal and thyroid problems associated with Down syndrome also have improved. And researchers are working on medications that can help improve the cognitive abilities of people with the disorder.
“Research has advanced, and there are potential golden promises on the horizon,” Skotko says.
Skotko, who has a sister with Down syndrome, was instrumental in helping to write the pamphlet, says the vast majority of women who receive a positive diagnosis don’t have enough information to make an informed decision.
In an anonymous survey of genetic counselors and other professionals, 23% admitted to purposefully over-emphasizing the negative information about Down syndrome or outright encouraging women to terminate their pregnancies, Skotko says.
Last month, Skotko and his colleagues released the results of surveys they conducted of people with Down syndrome, their parents and their siblings. The results, he says, paint a rosier picture than some genetic counselors portray.
Of the 2,044 parents who responded to the survey, 79% said they felt their outlook on life was more positive because of their child, while only 4% said they regretted having their child.
“When we asked people with Down syndrome directly, ‘What would you like to tell expectant parents?’ They emphasized that their own lives are good,” Skotko says. “One person said, ‘If everyone was as happy as me, that would be great.’ ”
This is why improved diagnostic tools raise ethical questions, Borke says. “This is really the first of this kind of test, but it won’t be the last.”
‘We are at an historic crossroads. As research is advancing and making possibilities greater for people with Down syndrome, it’s coming at a time when more women are given diagnoses” and having to determine whether to continue with their pregnancies, Skotko says. “If fewer people with Down syndrome are born, the focus given to people with Down syndrome will probably be diminished.”
Ethicists say that screenings like this are always fraught, pitting humanity’s quest to conquer disease against our collective belief that a diverse society is a richer one. Yes, prenatal tests are diagnostic, but there is another word for them, too.
“We have to understand that we are engaged in a project of eugenics,” Wolpe says. “It’s not Nazi eugenics, but we are creating embryos, we are testing them and we are deciding which ones are fit to implant.
“Calling it eugenics does not make it wrong,” he adds. “I use it to shock people into recognizing that it’s not simple.”
While couples who wanted to pass down certain traits previously had to rely solely on mate selection, advances in prenatal testing and pre-implantation screenings is changing all that.
“This is the beginning of a long-term enterprise of eugenics whereby we are about to have more and more powerful technologies that will allow us to determine the physical and genetic legacy of our children,” Wolpe says. “That’s one of the greatest ethical questions of our time.”
* CDC estimates that each year about 6,000 babies, or 1 out of every 691 children born in the United States, has Down syndrome.
* Life expectancy is on the rise. Thirty years ago,aperson with Down syndrome could expect to live to 25. Today life expectancy is 55, with many living into their 60s and 70s.
* Common complications associated withDownsyndrome include: birth defects of the heart, blocked small intestines, hearing problems, thyroid problems, skeletal problems and mild retardation.
* The risk of carryingababy with Down syndrome increases as a woman ages. Women who are 34 when they become pregnant have a 1 in500 risk of carrying a baby with Downsyndrome, but thatnumber jumps to 1 in385 when she turns 35. By the time she is 40, her chances become 1 in106.
* 92%of motherswhogetadefinitive diagnosis of Down syndrome in the womb choose to terminate. That test is invasive today; but a simple blood screening was introduced last month.