UK researchers clone three-parent embryos intended for implantation

Researchers at the University of Newcastle have created three-parent embryos in the lab as part of research into genetic diseases involving the mitochondria, reports Hilary White, LifeSiteNews.com. The ten cloned embryos were constituted from genetic material collected from two women and one man, and the alteration - should the child be implanted in the womb and allowed to develop normally - could be carried through generations.

The embryos were created by removing the nucleus from an existing donated single-cell embryo, created by in vitro fertilisation and considered "at risk" for mitochondrial genetic disease, and inserting it into the donated ovum of a second woman. The resulting cloned embryo would be free of the mitochondrial abnormality since the mitochondria are inherited only from the female sex cells and not from the nucleus of the embryo.

An embryo created with this technique, the researchers speculate, could be implanted and the child would be free of the defective mitochondrial DNA. This technique qualifies as germline alteration since the resulting genetic change would be carried through to future generations if the embryo were allowed to survive to birth and reproduce later in life.

Lead researcher, Professor Douglas Turnbull, denied the procedure was a form of cloning and told the BBC that the breakthrough may allow children to be born free of mitochondrial disease within ten years.

The Human Fertilisation and Embryology Authority (HFEA) allowed the research to go ahead with a special license, but changes to the law are being considered that could make such special permission unnecessary.

Josephine Quintavalle of the think tank Comment on Reproductive Ethics (CORE) said she was "absolutely terrified" at the HFEA's willingness to allow such experiments. "It is human beings that they are experimenting with," she added.

The experiment, presented last week to the Medical Research Council Centre for Neuromuscular Diseases, is intended to halt the inheritance of mitochondrial genetic disorders being passed through generations. Mitochondria are "organelles" or cell particles that are sometimes described as "cellular power plants" because they generate most of the cell's chemical energy. They are separated from the cell's nucleus and have their own independent genome, or genetic makeup.

Genetic diseases involving the mitochondria are those that affect the function of the mitochondrial DNA (mDNA). Mitochondrial disorders are rare, but many have devastating effects, including deafness, blindness, heart disease, diabetes, stroke-like episodes, seizures and mental retardation. One such disorder, Leigh's disease, affects the central nervous system, causing degradation of motor skills and eventually death. Most mitochondrial disorders are currently incurable.

The Daily Telegraph reports that the creation of the embryos was followed by an amendment tabled in the House of Lords by Lord Walton of Detchant to the Human Fertilisation and Embryology Bill that would allow such research to continue without special permission from regulating authorities.

"We are hoping to do this in the next three years," said Professor Turnbull. "We don't then want to wait another three years for the law to change."

Quintavalle told the Telegraph that mitochondria were "written off as unimportant" in the recent debate in the House of Commons about animal human hybrid embryos in the proposed Human Fertilisation and Embryology Bill, yet "suddenly it matters so much you want to do a mitochondrial transplant."

In similar debates in the Canadian House of Commons, experts warned that clones could be created in exactly the manner achieved at Newcastle; but these warnings were dismissed by pro-embryo research MPs as alarmism. Liberal MP, Dr. Carolyn Bennett dismissed out of hand the concept that a cloned human being could be created with more than two progenitors using mitochondrial transfer, a possibility that was specifically pointed out by pro-life researchers.

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[02/06/2008]

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