Doctors Debate Controversial Test for Down’s Syndrome

At least four biotech companies have developed a non-invasive, but accurate test, to detect Down’s syndrome during the first trimester of pregnancy, according to the Washington Post.

In 2007, the American College of Obstetricians and Gynecologists recommended that all women be offered screening tests for Down syndrome, which causes mental retardation and other health problems. The current tests consist of a combination of blood tests and ultrasounds. Depending on the results, the women may then undergo either amniocentesis or chorionic villus sampling (CVS) to confirm or rule out the diagnosis.

But the screening tests often produce imprecise results, and amniocentesis, the most common definitive test, can cause miscarriages and is not usually performed until the second trimester, when the termination of a pregnancy is much more traumatic and difficult to obtain.

The new tests take advantage of techniques that can isolate and analyze tiny bits of genetic information from the fetus that circulate in a woman’s bloodstream, in this case from cells or free-floating snippets of DNA or the related molecule RNA.

At least four companies are developing such tests, including Sequenom of San Diego, which plans to be the first on the market in June. The other companies hope to have their versions on the market within a year.

At a meeting of the Society for Maternal-Fetal Medicine in San Diego last month, the company reported that results from 858 women showed that its test did not miss a single case of Down syndrome and produced only one false alarm, making it much more accurate than the currently available screening tests and on a par with amniocentesis.

Initially, Sequenom plans to offer the test as an alternative to the first-trimester screening blood-and-ultrasound test. By reducing false alarms, the test could help many women obtain a more definitive diagnosis without the risks of amniocentesis or chorionic villus sampling.


The test has raised brows in the disabled community that is urging Congress to enforce a law passed last year requiring doctors to give mothers accurate information about genetic disorders and let them know there are resources to help them raise their babies.

Advocates worry that such tests could increase the number of women getting inaccurate information that makes life for people with Down syndrome and their families sound worse than it really is.

“We have a nation of physicians who are unprepared for explaining a diagnosis of Down syndrome,” said Brian Skotko, a physician at Children’s Hospital in Boston who works with the National Down Syndrome Society. “Many overemphasize the negative consequences or outright urge women to terminate their pregnancies.”

Skotko, whose sister has Down syndrome, predicted such tests would result in fewer babies being born with the condition.

“Every day my sister teaches me lots of life lessons — to laugh when others are mocking me, to keep on trying when obstacles are thrown my way,” he said. “If there were a world with fewer people with Down syndrome, I think the world would miss all these important lessons.”

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