New Down Syndrome Test Hailed as Promising

Prenatal Genetic Testing

Sequenom's stock jumped 78 percent in June when the new product was announced. And even though doctors said the test faces more hurdles, its "approach" could revolutionize the way doctors diagnose other chromosomal abnormalities.

"This is an innovative company, and the technology that is under development shows huge promise," said Dr. Laird Jackson, professor of obstetrics and gynecology in genetics at Drexel College of Medicine in Philadelphia. "They have the basis for a test, but it isn't clear how applicable it is."

Shulman agreed. "Ultimately, for this to be widely used and seen as medically appropriate, it would need the support of professional organizations like the American College of Obstetricians and Gynecologists [and other bodies]," he said. "Without rigorous and robust testing, none of these professional organizations are going to jump on board."

But the approach is a novel one. Down syndrome most often occurs when a child has three copies of chromosome 21. Unlike previous blood tests that measure protein markers in the mother and only predict the likelihood of Down syndrome in the fetus, this test looks at the fetus's genes. In the first small trial on humans, the test showed no false positives.

Safer for Mother and Fetus

And if it turns out that the test is a reliable one, Sequenom executives said, it could be a boon for expectant mothers.

"It's a better mouse trap," said CEO Harry Stylli. "I don't want to trivialize this, but it is a superior mouse trap, safer for the mother -- a simple blood draw -- and safer for the fetus."

For decades, amniocentesis has been the gold standard of prenatal testing, performed on 430,000 to 600,000 women a year. The procedure is usually performed at 18 weeks gestation when termination can be traumatic. Doctors insert a needle into the uterus and withdraw amniotic fluid, which can cause fetal injury or miscarriage in one out of 200 patients.

Chorionic villus sampling -- testing the placental tissue -- is also invasive, and can be done at as early as 10 weeks, but it carries a one in 100 risk of miscarriage.

Newer, noninvasive blood serum tests can be done earlier, but yield a 5 percent false positive rate. Each year about 40,000 of the 3 million who take the blood test are directed toward amniocentesis for follow-up.

"That's a dilemma for women," said Stylli, who said SEQureDX will soon complement and perhaps one day replace amniocentesis. It can be offered at as early as 12 to 13 weeks.

Pregnancy and Down Syndrome

The National Down Syndrome Society has said in a prepared release that although the new test "may provide improved safety and more accurate results," explaining those results can be problematic.

According to a survey that was cited in the medical journal Pediatrics, nearly 25% of doctors admit to giving patients negative information or actively urge parents to terminate their pregnancies.

Dr. Brian Skotko, a senior resident at Children's Hospital in Boston who has a 28-year-old sister with Down syndrome, conducted a survey that revealed, "The majority of mothers said that doctors were incomplete, inaccurate, or offensive when it came to delivering a diagnosis of Down syndrome."

He said that according to some research, an estimated 90 percent of mothers who chose to terminate a pregnancy because of Down syndrome considered the condition "too severe, that they would be sad all the time and would be a burden to the family."

Page
  • 1
  • |
  • 2
  • |
  • 3
Join the Discussion
You are using an outdated version of Internet Explorer. Please click here to upgrade your browser in order to comment.
blog comments powered by Disqus
 
You Might Also Like...