Jan. 15, 2003 -- Babies conceived though in vitro fertilization (IVF) have an increased risk for rare genetic disorders, new research shows.
Although the findings are preliminary, researchers say two recent studies indicate that the process of assisted reproduction can cause the genetic disorder known as Beckwith-Wiedemann syndrome (BWS). New research from the United Kingdom, published in the January 2003 issue of the Journal of Medical Genetics, shows that children with the syndrome are four times more likely than the general population to have been conceived by assisted reproduction. A similar study of BWS patients conducted in the U.S. found that patients were six times as likely to have been conceived through in vitro fertilization (IVF).
Although the numbers are small -- with six identified BWS cases out of roughly 40,000 assisted reproduction births during the time of the U.K. study -- they offer some of the strongest evidence yet that assisted reproduction techniques can carry a risk of genetic imprinting disorders.
"The theory is that assisted reproduction could change the normal process by which an imprint or a gene pattern expresses itself at a very early stage in the process of cell division," study author Trevor R. Cole, MD, of the University of Birmingham, England, tells WebMD. "Our study is certainly not conclusive, but there are more cases than you would expect to see coincidentally."
Cole and colleagues found that three of the 149 babies with BWS in their registry were conceived through IVF and another three were conceived through intracytoplasmic sperm injection or ICSI, in which the sperm is injected into the egg.
Suspecting a link between BWS and assisted reproduction, U.S. researchers recently examined the history of 64 BWS patients and found that three, or 4.6%, were conceived through IVF. The findings, by researchers at Baltimore's Johns Hopkins Medical Institutions and St. Louis' Washington University School of Medicine, were first reported last November.
Lead author Andrew Feinberg, MD, of Johns Hopkins, also conducted genetic testing to look for patterns associated with BWS. Abnormal imprinting of the genes normally accounted for about half of BWS cases, and Feinberg found these changes in five of seven patients conceived through IVF.
Feinberg tells WebMD that more study is needed to clarify the link between BWS and assisted reproduction techniques, but he is disappointed with the response within assisted reproduction circles.
"It is possible that this is preventable, but we will never know until this is studied further," he says. "We were hoping that our study would prompt the IVF community to look at this issue, but that has not been the reaction. The message to fertility doctors is loud and clear."
Ob-gyn and geneticist Joe Leigh Simpson, MD, agrees that more research is needed to determine the link between BWS in children conceived through assisted reproduction. But he says the number of cases is likely to be so small that they will not dissuade infertile couples who are considering assisted reproduction. Simpson is chairman of the ob-gyn department at Baylor College of Medicine and is past president of the American Society for Reproductive Medicine.
There have been a million IVF babies born now, he says, and there has not been a trace of concern that the overall frequency of genetic disorders with standard IVF is any different than the population as a whole," he tells WebMD.