February 5, 2008

Three-Parent Embryo Created By Scientists

In a potential breakthrough for the treatment of serious hereditary diseases, British Scientists from Newcastle University have created ten test-tube human embryos, each containing the DNA from one man and two women.  

The scientists, led by Professor Doug Turnbull, believe the procedure could someday be used to prevent women with faults in their mitochondrial DNA from passing the disease on to their children. Mitochondrial DNA is passed down only through the female line.

Mitochondria are tiny "batteries" inside cells that provide their energy. Faulty genetics can mean mitochondria do not completely burn food and oxygen, leading to the build-up of poisons responsible for more than 40 different diseases.  These diseases, some of which lead to disability and death, affect one in 5,000 children, and include fatal liver, heart and brain disorders, deafness, muscular problems and forms of epilepsy.

At present, no treatment for mitochondrial diseases exists. However, Professor Turnbull and his team believe these diseases could be prevented if at-risk embryos were given an effective mitochondrial transplant.

The process involves in vitro fertilization (IVF) and the subsequent removal of the egg's nucleus. The nucleus is then placed into a donor egg whose DNA has been removed.  Any baby born through this method would have genetic elements from three people, but the nuclear DNA that influences appearance and other characteristics would not come from the woman providing the donor egg.  In other words, the resulting fetus inherits genes from two parents but mitochondrial DNA from a third party.

If all goes well, researchers believe they may be able to start offering the technique as a treatment in three to five years.  For now, the team only has permission to carry out the lab experiments.

"The idea is simply to swap the bad diseased mitochondria -- give a transplant, if you like -- for good healthy ones from a donor," Patrick Chinnery, a member of the Newcastle team, said in a telephone interview with Reuters.

"We're trying to prevent kids being born with fatal diseases," he said.

Professor Chinnery told BBC News, "We believe that from this work, and work we have done on other animals that in principle we could develop this technique and offer treatment in the foreseeable future that will give families some hope of avoiding passing these diseases to their children."

Dr. Marita Pohlschmidt, of the Muscular Dystrophy Campaign, which funded the research, was confident it would lead to a breakthrough in treatment.

"Mitochondrial myopathies are a group of complex and severe diseases," she told BBC News. "This can make it very difficult for clinicians to provide genetic counseling and give patients an accurate prognosis."

However, the research has attracted opposition from critics of human embryonic research who fear the creation of designer babies.

Josephine Quintavalle, of the pro-life group Comment on Reproductive Ethics, told BBC News it was "risky, dangerous" and a step towards "designer babies".

"It is human beings they are experimenting with," she said.  "We should not be messing around with the building blocks of life."  Mrs. Quintavalle said embryo research in the U.S. using DNA from one man and two women was discontinued because of the "huge abnormalities" in some cases.

All of the three-parent embryos created in the research were destroyed after six days.
The researchers presented their findings at the Medical Research Council Center for Neuromuscular Diseases conference in London on February 1-2, a university spokeswoman said.


On the Net:

Newcastle University

Muscular Dystrophy Campaign