Genetic Differences for 'Test Tube' Babies?

Researchers Look for Clues to Health Risks in Babies Born via Assisted Reproductive Technologies

From the WebMD Archives

Feb. 22, 2010 -- Babies born via IVF and other assisted reproductive technologies (ART) have more genetic differences than do babies conceived naturally, according to a researcher, although the majority of the ''test tube'' babies he studied are still within the normal range.

''There's not a big difference between the two groups of kids, so it's comforting," says researcher Carmen Sapienza, PhD, professor of pathology and laboratory medicine and acting director of the Fels Institute for Cancer Research at Temple University Medical School in Philadelphia. He presented findings from his study at this week's American Association for the Advancement of Science annual meeting in San Diego and published his findings in Human Molecular Genetics.

The information, as it evolves, should help parents of ART babies -- and the children themselves, as they mature -- stay aware of any additional health risks associated with the genetic differences and take preventive action, Sapienza tells WebMD.

Since the first ''test tube baby'' was born in 1978, more than 3 million children have been born with the help of ART.

Health Risks of ART Babies

Experts have known that as a group, ART children are at greater risk for some birth defects and for being born at a low birth weight, which in turn is associated with risks for obesity, high blood pressure, and type 2 diabetes later in life.

So, Sapienza and his colleagues looked at samples of placental and cord blood DNA from 10 ART children and 12 children who had been conceived naturally. The researchers were looking for differences in the levels of DNA methylation -- a type of modification that turns genes on and off.

Turning on a particular gene, Sapienza says, may be linked with a higher risk for disease -- for instance, a gene that controls glucose metabolism, when turned on too much, may be associated with type 2 diabetes.

First, researchers looked at the DNA methylation marks in 800 genes in the two groups of children, Sapienza says. "What we found is between 5% and 10% of the genes have significant differences between the two groups in the methylation, depending on whether we were looking at placental or cord blood."

Continued

They also found these differences sometimes resulted in differences in the expression of nearby genes, the way they are turned on or off.

What's not known, Sapienza says, is whether the differences are the result of ART or are associated with other factors, such as the infertility itself.

Several of the genes whose expression was found to differ between the groups have been linked with the development of fat tissue and glucose metabolism. Still, only a small fraction of the ART babies, despite the differences observed, were found to be outside the ''normal'' range, Sapienza says.

Second Opinion

The new findings are believed to be the first to show on a molecular basis differences between ART children and other children, says Marvin L. Meistrich, PhD, professor of experimental radiation oncology at the University of Texas M.D. Anderson Cancer Center, Houston.

"It's not a cause to worry," says Meistrich, who participated in a symposium that presented the study's findings at the American Association for the Advancement of Science meeting.

''Yes, he found some abnormalities associated with the process but the abnormalities may be very subtle," Meistrich tells WebMD.

The study findings are preliminary, he says, and the information about differences is expected to evolve as more work is done in the area. Those who have had ART children or are ART children themselves should try to follow the research findings closely, Meistrich says.

If further research links specific genetic differences in ART children to specific diseases, ''they could become proactive and start to monitor or take preventive measures for that disease."

For instance, if genetic differences prove to boost the risk for colon cancer, the ART-conceived person may opt for routine colonoscopy at an earlier age.

WebMD Health News Reviewed by Louise Chang, MD on February 22, 2010

Sources

SOURCES:

Carmen Sapienza, PhD, professor of pathology and laboratory medicine; acting director, Fels Institute for Cancer Research, Temple University Medical School, Philadelphia.

Marvin L. Meistrich, PhD, professor of experimental radiation oncology, University of Texas -- M.D. Anderson Cancer Center, Houston.

American Association for the Advancement of Science annual meeting, Feb. 21-22, 2010, San Diego.

Katari, S. Human Molecular Genetics, July 15, 2009 online.

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