Oct 8, 2008 4:42 pm US/Eastern
Researchers Create Safer Testing For Down Syndrome
LOS ANGELES (CBS4) ―
Parents-to-be could soon have an easy, safe way to test their baby for genetic defects. Up until now the only way to get a genetic reading on a fetus was through a very invasive procedure that also risked miscarriage.
Now a new blood test is not only simple, it can also be performed very early in pregnancy.
It's a difficult decision for man expecting parents to test, or not test, for genetic defects.
"Just the thought of a long needle going through the belly and having to actually pierce the placenta was very nerve-wracking for us. Because we tried for a long time to have a baby," said expectant mom Teri Theuriet.
Prenatal testing for disorders like Down syndrome is not only invasive, but risky. During a medical procedure called amniocentesis, a needle draws fluid from the placenta which slightly increases the chance of miscarriage. But now researchers at Stanford University have now developed a new test that eliminates the risk.
"There has been a decade-long search for a non-invasive test for Down syndrome, and I think we've taught the world how to do it now," said Dr. Stephen Quake, a bioengineer with Stanford.
First, doctors draw a few tablespoons of blood from the mother.
"That gives us a window into the genetics of the baby," said Quake.
Using a computer, doctors find DNA fragments of the fetus in the mother's blood and then match the DNA to chromosomes, too many copies of any one chromosome is a red flag; Down syndrome, for example, involves an extra copy of chromosome 21.
Quake says because fetal DNA starts showing up in the mother's blood in the first few weeks of pregnancy, this new test can be done at about 5 weeks which is much earlier than current testing which is around 4 months. Further study is underway, researchers hope this new test will be available to parents within a few years.
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