Prenatal test presents dilemmas to expectant mothers | News

By Maureen Salamon
HealthDay Reporter

FRIDAY, Sept. 28 (HealthDay News) -- A
sophisticated genetic test sometimes used during pregnancy can't always
predict if chromosomal abnormalities will cause problems in children,
leading some mothers to label the information "toxic knowledge" they
wish they hadn't received, a small new study shows.

Researchers from three universities found
that expectant mothers receiving bad news about a genetic test called a
DNA microarray -- more often used after birth to identify chromosomal
problems in children with unexplained delays or defects -- reported
mostly negative responses, ranging from feeling blindsided to needing
support to digest the information and make critical decisions about
their pregnancies.

The women's reactions challenge the notion
that knowledge is power, especially when that knowledge pertains to
ambiguous information about an unborn baby's health, said study author
Barbara Bernhardt, a genetic counselor and clinical professor of
medicine at the Hospital of the University of Pennsylvania.

"I think we need to have better information
readily available to patients and providers . . . to make the decisions
they need to make in a timely manner," Bernhardt said. "We also need
additional education of obstetricians and midwives to feel more
comfortable talking to patients about it and counseling them about the
results."

The study was published online recently in the journal Genetics in Medicine.

Standard DNA testing offered to pregnant
women uses tests such as amniocentesis and chorionic villus sampling,
which involve "karyotyping" to identify common abnormalities such as
Down syndrome. But DNA microarrays can detect smaller-scale chromosomal
changes that can signal future problems such as autism or congenital
disorders, although the test can't necessarily predict how severe the
problem will be or even if a gene variant will produce any discernible
conditions in the child.

Some of the 54 study participants, 23 of whom
were interviewed at least six months after childbirth or pregnancy
termination, had learned from ultrasound or other tests that their fetus
had abnormalities. But for those whose prior tests had come back
"normal," learning their baby had genetic variants of unknown
significance sent some of them into a tailspin.

Bernhardt's team identified five key
responses that described the women's experiences, including considering
the microarray results toxic knowledge they wish they hadn't learned.
Many of the women accepted the testing -- which costs between $1,500 and
$3,000 -- because it was offered at no charge to them, which they felt
was "an offer too good to pass up."

Unlike children who are tested using DNA
microarrays to help diagnose existing problems, children tested
prenatally may never develop health or developmental issues arising from
their genetic variants. "We discovered in the course of the study that
some of the parents have the same [chromosomal] deletion or duplication
as their fetus" but never suffered any ill effects, said Bernhardt, also
co-director of the Penn Center for the Integration of Genetic
Healthcare Technologies.

However, "the horse is out of the barn," she
added. "This test is there, it's available, which is why we have to
provide good information and careful counseling."

Sandra Darilek, a genetic counselor and
clinical instructor at Baylor College of Medicine in Houston, said the
vast majority of results presented by microarray testing are
straightforward, but every genetic condition presents differently, from
mild to severe.

"In a lot of cases, it's an incredibly useful
test because if they get a normal result, it can be very reassuring for
a patient," Darilek said. "But it also depends on the point of view the
patient is coming from. Some want all the information possible and are
willing to take uncertainty, and some want straightforward information."

Because technology is continually advancing, ambiguity will always be part of newer medical tests, Darilek noted.

"I don't know that uncertainty will ever be
completely absent from prenatal testing at all until we have a handle on
our complete genome," she added. "But with the platform of testing we
currently have, if it would stay static, within a few years we'll have
an even better grasp on some of these [genetic] variants that are new to
us now. But it's going to be an ever-evolving situation."

More information

The American Academy of Family Physicians has more about prenatal diagnostic techniques.

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