Maternal Blood Test Might Reveal Fetal Health

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Maternal Blood Test Might Reveal Fetal Health

Early research points the way to safe, accurate

prenatal screen

By Randy Dotinga

HealthDay Reporter

FRIDAY, Oct. 7 (HealthDay News) -- New research is

moving scientists closer to the holy grail of prenatal

medical care: a maternal blood test that could reveal

health problems in an unborn child.

Researchers from Hong Kong reported this week that

they've discovered a potential new way to

differentiate the DNA of the mother from that of the

fetus in a maternal blood plasma sample. The key, they

say, lies in a DNA trait that's much more common in

maternal genetic material.

Specialists couldn't predict how long it may take for

the findings to translate into a routine fetal DNA

screening test available in the doctor's office. And

the study results don't appear to have any bearing, at

least for now, on controversial fetal DNA tests that

promise to predict a baby's gender early in pregnancy.

Still, the research is promising, said Dr. Siobhan

Dolan, associate medical director at the March of

Dimes. " This study is a step in the right direction, "

she noted.

Currently, the best screening tests for fetal medical

problems -- including amniocentesis -- are also

potentially dangerous to the unborn child. Doctors and

researchers have been looking for a noninvasive test,

and a test using the mother's blood would certainly

fit the bill (current blood tests for pregnant mothers

don't directly measure the health status of the

fetus).

The good news is that a small bit of fetal blood does

blend in with the mother's blood. " The trick is to

find a way to sort out in the blood what came from the

fetus and what came from the mother, " Dolan said.

Only about 3 percent of DNA in maternal blood plasma

comes from the fetus, said study author Dennis Lo, a

professor of chemical pathology at the Chinese

University of Hong Kong. There are ways to

differentiate the fetal DNA, such as looking for the

male Y chromosome, he said, but that only works for

male fetuses.

In the new study, Lo and his colleagues report that

they can differentiate maternal from fetal DNA by

looking for a specific gene that acts differently in

mothers and fetuses. They also used their technique to

accurately detect cases of pregnancy-associated

hypertension, also known as preeclampsia, in pregnant

women.

The findings appear in this week's early online

edition of the Proceedings of the National Academy

Sciences.

Earlier this year, researchers reported that they were

able to more easily analyze fetal DNA by boosting its

levels in blood samples. Scientists have also found a

way to separate bits of maternal and fetal DNA by

analyzing their size.

The new research may have implications for existing

fetal DNA tests, such as those that detect potentially

dangerous blood group incompatibilities between mother

and fetus, Lo said. It's not yet known if the tests

will help pick up other diseases like Down syndrome,

but researchers are hopeful, Lo said.

More information

To learn more about the types of prenatal tests that

are currently available, go to the March of Dimes

(www.modimes.org ).