Simple Test Could Detect Down's Syndrome
Using a technique called fluorescence in-situ hybridization (FISH) -- where fluorescent markers are used to paint a picture of the part of the chromosome under investigation -- the researchers were able to pinpoint fragments of fetal DNA.
In all three Down's syndrome cases, they were able to detect the chromosomal abnormalities from the mother's blood early on in the pregnancy. After each woman had CVS testing, they checked the samples again and found the same defects.
"These results indicate that these cells were present in maternal plasma before the invasive procedure," the researchers write. "We have shown that prenatal detection can be accomplished by FISH analysis of fetal cells harvested from maternal plasma. The procedure is simple, and our data suggest future large-scale trials should be initiated to assess the diagnostic accuracy of this method."
Despite the fears of miscarriage, tests like amniocentesis and CVS are relatively safe, says Deborah Driscoll, MD, associate professor of medicine at the University of Pennsylvania's department of obstetrics and gynecology in Philadelphia. But because of the miscarriage fears, doctors are looking to make more options available. That is what's motivating investigators like the ones here to look for tests that are easier to do and come with lower risks than those commonly used today.
As for this research, "this is very preliminary and interesting, but it's still too premature if this will be clinically useful," says Driscoll, a geneticist and obstetrician at Penn.
"Clearly it is easier to do this test, but whether it will be as sensitive [as the standard tests today] remains to be seen," she tells WebMD.
Driscoll says that CVS and amniocentesis give more information than just the signals of Down's syndrome. Doctors get the number of chromosomes present and they can see the chromosomes' structure. Clinicians are not going to stop doing these standard tests and lose all that other important information in order to do a test for just one genetic abnormality. But the study should spark more research into finding more testing options for future patients, she says.