New Down Syndrome Test Hailed as Promising
Sept. 5, 2008 — -- Unlike Republican VP nominee Sarah Palin, an estimated 87 percent of all women carrying a child with Down syndrome don't learn the news until delivery.
"I was grateful to have all those months to prepare," Palin, who underwent amniocentesis five months before the birth of her son, Trig, told People magazine. "I can't imagine the moms that are surprised at the end. I think they have it a lot harder."
One in every 733 babies -- or around 5,500 each year -- is born with Down syndrome, the most common genetic condition in the United States, causing an array of physical and mental challenges for both child and parents.
Until now, prenatal genetic testing for Down syndrome has either been too late, too invasive or inaccurate, giving women little choice in whether to carry or terminate the pregnancy.
But now, one company is investigating the possibility of a new non-invasive blood test, administered as early as 12 to 13 weeks into the first trimester, that detects genes that are behaving in a way that is linked to Down syndrome.
In an experiment earlier this year, the test has already been used to screen the fetuses of 200 pregnant women, with no false negatives. Further testing involving more women is scheduled for this month.
Despite early promise, the testing is still in its early phases. Dr. Lee Shulman, head of the Section of Reproductive Genetics at Northwestern University's Center for Genetic Medicine, has investigated fetal DNA testing since the late 1980s. He said that it remains anyone's guess as to whether the test will eventually become a viable early screening or diagnostic offering for curious expectant moms.
"The medical community knows very little about this," Shulman said. "I am somewhat concerned about this company going with investors and marketers rather than waiting for robust and significant clinical trials... Why are they talking about marketing when they don't have anything that has been put to the test?"
Still, Shulman said the idea of such a screening -- which if proven to work, could offer what he said would be the first ever first-trimester direct genetic testing for the condition -- is "fascinating."
But advocacy groups warn that the test -- which gives women the option to end a pregnancy sooner -- could diminish an already small population of about 400,000 that has Down syndrome.
About 90 percent of women who learn they are carrying a child with Down syndrome choose to end their pregnancies, and easier testing could increase those numbers, stymying support and fundraising for the disorder.
And some say the expanded technology raises ethical questions
"It's 'Gattaca World,'" said Los Angeles filmmaker Will Drinker, referring to the 1997 movie about a society that analyzes its citizens' DNA to determine where they belong.
"It's a dead race, but there'll be a whole new race of perfect people that have blue eyes and blond hair and are what their parents want," said Drinker, whose 23-year-old brother has Down syndrome. "I am afraid of the opposite of Dan."
The prenatal test, called SEQureDX , is being developed by the San Diego-based company Sequenom, which will conduct further studies this fall and hopes to market the product in early 2009.
