Genetic Differences for 'Test Tube' Babies?
Researchers Look for Clues to Health Risks in Babies Born via Assisted Reproductive Technologies
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
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
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
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.