New genetic test provides precise, yet hazy results

by jeeg 20. November 2012 19:59

A new test, called chromosomal microarray technology, is providing doctors and prospective parents with more information than ever before about the genetic makeup of a baby still in the womb.

But what that knowledge actually means is not always clear, causing confusion and anxiety for parents and physicians.

Michelle Catalano had no reason to think her fourth baby wouldn't be born as healthy as her other three.

But because the Eastchester, N.Y., resident was 36 -- a year into the territory obstetricians ominously describe as "advanced maternal age" -- she was given the option of using the new technology to test whether her baby was developing free of genetic defects that could signal trouble.

"It's an evolving technology," said Dr. David Kronn, chief of medical genetics at Maria Fareri Children's Hospital at Westchester Medical Center in Valhalla, N.Y. The results, he said, aren't always cut and dried.

Dr. Susan Klugman, an obstetrician in Larchmont and Yonkers, N.Y., and 300 of her patients recently took part in a nationwide study of chromosomal microarray technology to determine how effective the method is.

"This zooms down and looks at the specific genetic material in the chromosomes to make sure nothing is missing or nothing is extra," said Klugman, director of reproductive genetics at Montefiore Medical Center and an associate professor at Albert Einstein College of Medicine.

Initial results of the study submitted early this year at the Society for Maternal-Fetal Medicine showed that prenatal chromosomal microarray technology can detect more genetic abnormalities than current methods.

Klugman now offers the test to select patients in her practice.

Even as the test grows in use, experts caution that it may raise more questions than it answers.

"Our capacity to test and our capacity to make sense of the results are not well-aligned," said Nyack, N.Y., resident Rachel Grob, who has done research into genetics, advocacy and the social impact of technological innovation.

She recently wrote a book, "Testing Baby: The Transformation of Newborn Screening, Parenting and Policymaking," that examines the unintended consequences of obtaining genetic information at and before birth.

Chromosomal microarray involves looking at tiny pieces of DNA to detect small duplications or missing pieces of each chromosome.

By doing that, the test can identify mutations linked to more than 150 disorders that result in developmental and physical abnormalities.

The test is more detailed than the current technology, called karyotyping.

Both involve taking a sample from the amniotic sac or from the placenta -- methods that involve a degree of risk to the growing fetus.

Costing about $1,500 -- the same as similar tests -- an increasing number of insurers are covering it.

Though chromosomal microarray is more detailed than current tests, it sometimes reveals abnormalities on chromosomes that aren't linked to any known condition.

"Even if there is an abnormal finding, it may not be clinically significant," Kronn said.

Many people have minor defects on their chromosomes that are harmless. Before the advent of technology like chromosomal microarray, most of those people never even knew it.

"It's such (a) powerful technique, but sometimes we don't know what the information means," Kronn said.

It is difficult for physicians to counsel patients when the results are unclear.

"Patients are grappling with very difficult decisions," Klugman said.

Catalano started having second thoughts about the test almost as soon as amniotic fluid was drawn from her uterus.

"Do I really want to know everything this is going to tell me?" she recalled.

It was a tough two weeks before she got the news: Her baby was fine. Luca Catalano arrived several months later -- healthy, as expected.

As the test becomes more widely used, an increasing number of women will have to grapple with the issue of a powerful genetic test that sometimes delivers puzzling results.

That creates a "heavy burden" for families, Grob said.

"Before we had all this technology we had babies and we dealt with the hand we received," she said.

"We didn't feel responsible for having to decide to terminate a pregnancy or choosing to have a child with a disability."

Jane Lerner Gannett, The Town Talk
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