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Monkeys with Mito have Normal Babies - with a little help

Cristy's note - Rob from Bloomberg News called me this week and I connected him with Vamsi Mootha for an expert opinion.  What do YOU think?  Post a comment- share your thoughts!

Gene Mix in Monkeys Fixes Defects, Opens New Ethics Debate



By Rob Waters

Aug. 26 (Bloomberg) -- Mixing in genetic material from one monkey at the point when two others conceive helped replace defective DNA to produce healthy babies, and may one day keep humans from passing on rare flaws, scientists said.

The experiment by researchers at the Oregon Primate Research Center in Beaverton is designed to replace defective DNA in the mitochondria, energy-producing elements of cells necessary for metabolic processes. The scientists reported the findings today in the journal Nature.

The new technique might provide a way for women with mitochondrial disease to have children without passing on their defective genetic material, according to scientists. Because the technique permanently alters part of the offspring's DNA, it also may open a path to modifying a baby's DNA to select for desired traits. That raises ethical concerns, scientists said.

"It's a very exciting experiment that would give parents the option of being able to have their own genetic children," said Arthur Caplan, director of the University of Pennsylvania's Center for Bioethics in Philadelphia. "It's also the classic example of the road to hell is paved with good intentions."

Defective mitochondria are passed only from mother to child, not from the father. About 1 in 4,000 births produce babies with defective mitochondria and can lead to a variety of diseases, said Vamsi Mootha, an associate professor of systems biology and medicine at Harvard Medical School in Boston who studies mitochondrial disorders. Nerve and muscle cells deprived of energy are particularly vulnerable to breakdown, leading to conditions like Kearns-Sayre syndrome that can cause progressive muscle weakness and death.

Genetic Traits

The genes that determine the traits of individuals, from their hair and eye color to their risk for many diseases, are found in the nucleus of each cell. Mitochondria are located outside the nucleus of cells and have their own DNA.

The team at the Oregon Primate Research Center led by Shoukhrat Mitalipov took the egg cells of a rhesus macaque monkey, plucked out the nucleus and inserted it into an another egg cell whose nucleus had been removed. The second cell retained its miochondria. It was then fertilized by another monkey's sperm and implanted in a surrogate mother who gave birth to twins named Mito and Tracker. Subsequent experiments led to the birth of two more single monkey babies named Spindler and Spindy.

"We believe this technique can be applied very quickly to humans and it will work," Mitalipov said in a telephone briefing yesterday with reporters.

Modifying Germ Cells

Scientists already have modified the genes of sperm and egg cells -- known as germ cells -- of laboratory animals, producing offspring with repaired DNA, according to a 2005 report from the Genetics and Public Policy Center, a Washington-based program of Johns Hopkins University.

Researchers have edged closer to applying such techniques in humans to prevent disease. Such efforts present unknown risks to the offspring and theoretically may be used to create designer babies. Researchers seeking to attempt gene therapies on the germ cells of humans are required to get approval from the U.S. Food and Drug Administration.

The team plans to seek approval from the Oregon Health and Sciences University in Portland and the FDA to conduct human trials, after the monkey babies have been followed for a few years to be certain they are healthy, Mitalipov said.

"We believe we've done some homework and have solid data" that shows the procedure to be "very efficient and safe," he said.

'Remarkable' Advance

Another technique now available allows doctors to assess the egg cells of women with mitochondrial diseases and pick the healthiest ones to use with in vitro fertilization procedures, Mootha said. While that approach should be used first, the new technique could help women with no adequate egg cells to have healthy babies, he said.

"It's a remarkable technical advance," Mootha said of the experiment. He also said it raises concerns that, for example, "they've essentially created non-human primates that have three biological parents."

Because it could help women with disease have healthy children, "it seems to be defensible, important and beneficial, said Caplan, the University of Pennsylvania ethicist. "It also opens the door to all manner of changes that are not so important and beneficial."

While mitochondrial DNA doesn't affect core human traits that are controlled by nuclear DNA, it does affect energy production, Mootha said. That opens the possibility of parents in the future trying to select robust mitochondria that could provide extra energy to help athletes perform at high levels, he said.

"Good mitochondrial DNA could facilitate athleticism, and reduce risk for obesity or diabetes," Mootha said. "It's a theoretical possibility that some people might want to use or misuse this technology for that purpose. This is a slippery slope."

To contact the reporter on this story: Rob Waters in San Francisco at

Last Updated: August 26, 2009 13:26 EDT

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kathy's picture



My understanding is that this technique has been successfully used for a number of years in USA and UK infertility clinics to help women (presumably with defective mtDNA) to bear children.

As with almost all medical procedures, there certainly is the potential for abuse. I guess we need to weigh that against the suffering that can be prevented. My mitochondrial disease is fairly mild compared to what some of the children have. There is no way I would want anyone, especially a child, to share it if there were another choice.

saltaylor01's picture



I see where the ethical debate would come in however for those of us with mitochondrial disease who have either passed it onto our children or would like to have children, this is a very important advancement. I knew that Dolly the Sheep had been 'cloned' in this way so I was wondering when further studies would be done. Unfortunately though this technique would 'only' help those with a mitochondrial DNA mutation and not those with a nuclear DNA mutation which causes mitochondrial diseases in, I believe, like 80% of cases. However, what a wonderful advancement for medicine!!!
arktjk's picture



I think this is great news for those with mtDNA mutations. I don't know how it would be for those with the nuclear deletions/mutations. For a couple years now I have been wondering if someone could replace the bad mitochondria with good or just add more good so that there would be more good than bad and the thresh hold level would be smaller. It's a little too late for me, but it is good news for the future. The only drawback is that many mothers do not know they have a mutation before they have a child, which was my situation.