DNA Swap Between Eggs May Curb Inherited Disorders, Study Finds

April 14, 2010, 4:59 PM EDT  BusinessWeek

By Kristen Hallam

April 14 (Bloomberg) — Scientists discovered a way to transfer DNA from one fertilized human egg to another in a pioneering effort to avert the spread of a host of genetic disorders such as learning disabilities and diabetes.

The researchers at Newcastle University in northern England extracted the genetic material contributed by the egg and sperm and implanted it into a donor egg, according to the study published today by the journal Nature. It’s the first time DNA has been transferred between two fertilized human eggs.

The approach discards almost all the defective DNA inherited from the mother that disrupts the tiny energy generators inside cells, and may prevent related disorders such as blindness and liver failure, the researchers said. They are planning further experiments to see whether the technique could help people who carry mutated genes to have healthy babies — an end result that may still be a decade away.

“We have no way of curing these diseases at the moment, but this technique could allow us to prevent the diseases occurring in the first place,” said Doug Turnbull, the lead researcher and a professor at the university’s medical school, in a statement. “It is important that we do all we can to help these families and give them the chance to have healthy children, something most of us take for granted.”

Parents contribute a total of 23,000 genes to a child. In a fertilized egg, this genetic material is housed in two pronuclei, one from the egg and one from the sperm. The egg also contains mitochondria, tiny structures found in every cell that produce the chemical fuel needed for life. Mutations in the mitochondrial DNA, which are passed on from the mother, can disrupt the functioning of these energy generators.

‘Changing the Batteries’

The Newcastle scientists were able to extract both pronuclei and implant the material that makes each child unique into a donor egg with healthy mitochondria. They created 80 fertilized eggs using the technique and grew them in a laboratory for six to eight days. That showed for the first time that eggs produced in this way could reach the stage at which they each had divided into about 100 cells.

“It’s like changing the batteries,” Turnbull said today at a news conference in London. “These are diseases where there is battery failure. Because mitochondria are everywhere, these diseases can affect all parts of the body. None of my patients is exactly the same.”

About 1 out of every 200 children is born each year with mutations in mitochondrial DNA that cause no symptoms or only mild conditions. One in every 6,500 children is born with a more serious mitochondrial disease, ranging from muscular weakness to fatal heart failure. Some disorders lead to death in early infancy.

The research was funded by the Muscular Dystrophy Campaign, the U.K. Medical Research Council and the London-based Wellcome Trust, the world’s second-biggest medical research charity.

–Editors: Phil Serafino, Angela Cullen

To contact the reporter on this story: Kristen Hallam in London at khallam@bloomberg.net

To contact the editor responsible for this story: Phil Serafino at pserafino@bloomberg.net

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