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Should scientists be allowed to change DNA to prevent genetic disease?

Panel recommends approval of 'three-person babies'

Published: Wednesday, Feb. 3 2016 12:00 p.m. MST

Pictured: In vitro fertilization. In mitochondrial gene therapy, a process that some scientists say is similar to in vitro fertilization, the mitochondrial DNA in an egg can be replaced with that of another woman.

Sukharevskyy Dmytro, Adobe Stock

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SALT LAKE CITY — A major bioethics panel, charged by the Food and Drug Administration with weighing the ethics of a DNA manipulation technique that would create so-called "three-person babies," has concluded that clinical investigations of the technique should be permitted, given certain conditions.

The technology — known as mitochondrial replacement techniques, or MRT — has been around for years.

But with understanding of genome editing now growing at a rapid clip, government agencies are asking scientists and ethicists for advice.

"I think the field has come together to say, 'Let’s think about this together and go forward carefully,'" said Dr. Jeffrey Botkin, a professor of pediatrics and chief of medical ethics and humanities at the University of Utah.

Botkin sat on the 12-person committee that included top bioethics experts from Johns Hopkins, Caltech and Harvard.

Mitochondrial replacement is intended to prevent children from inheriting mitochondrial diseases from their mother. It works by replacing some of the mother's defective DNA with the DNA of a second woman.

That means the resulting baby would theoretically have DNA from three genetic "parents" — nuclear DNA from a mother and father, and mitochondrial DNA from another woman.

In the committee's report, released Wednesday, the panel concluded it is “ethically permissible to conduct clinical investigations of MRT,” subject to stringent conditions.

The panel recommended that people proceed only if the research on animals has proved the technique to be safe and asked researchers to limit trials to women at risk of passing on a serious mitochondrial disease that would result in severe impairment or death.

They also recommended that researchers only implant male embryos to be born.

Because mitochondrial diseases are passed through women only, implanting only males would prevent any changes — and potential side effects — from being passed down to future generations.

The final decision is still up to the U.S. Food and Drug Administration. But the report from the National Academies of Sciences, Engineering and Medicine is likely to be taken seriously by the FDA and those in the medical field.

But the issue is likely to be controversial. To many, the concept of genetic engineering raises the specter of Dr. Frankenstein or clones — scientists "playing God."

Dr. Jared Rutter, biochemistry professor at the U. who is researching the links between mitochondria and cancer, called the recommendation "a profound step" forward.

But he also acknowledged that scientists have to be careful about how they use gene-modifying technology.

"There's not a bright line between where this kicks over into unethical," Rutter said. "The technology that we have is expanding … more rapidly than our sophistication with thinking about how to use it."

As a practicing Mormon, Rutter said he has no safety or ethical concerns about mitochondrial replacement. The technology is well-understood by many researchers and has proved to be safe in animals, according to Rutter.

He compared the technique to in vitro fertilization, in which eggs are fertilized outside of the body and reimplanted.

"There are several diseases that used to be a death sentence that are now treatable," Rutter said. "I consider this the latest in a long line of diseases that are now manageable because of the investment that society has made in research."

The Church of Jesus Christ of Latter-Day Saints declined to comment.

Dr. Dana Carroll, a biochemistry professor at the U., was one of 18 scientists and ethicists who signed a paper last year cautioning scientists from using new gene-editing tools to modify human embryos.

Carroll said technologies that alter people's inheritable traits — what some scientists call "crossing the germline" — raise safety and ethical concerns because those genes are passed down to future generations and enter the human gene pool.

Carroll said he's opposed to making cosmetic changes to a baby's appearance — so called "designer babies."

Mitochondrial replacement wouldn't do that — but it would alter the baby's genetic makeup. Those changes would be passed down through the baby to her daughters, her granddaughters, and beyond.

However, Carroll pointed out that many things people do can be considered a form of genetic modification.

"We determine the genetic makeup of our children by choosing our mates," Carroll said in an email. "And we probably influence our children’s fates more in their upbringing. In addition, the changes we are considering are very small in terms of the amount of DNA being modified, and most are in the interest of the health of the children."

Mitochondria contain 37 genes. Nuclear DNA — which is the kind that determines most of our appearance and health — contain 20,000 genes. In mitochondrial replacement technology, the 37 mitochondrial genes would be switched out as one package.

Most remember from biology class that mitochondria are the "powerhouse of the cell." They produce energy for the cell and contain tiny amounts of their own DNA.

Defective mitochondria can cause a range of problems for the baby, from muscular problems to blindness to death.

In mitochondrial replacement technology, scientists remove the nucleus from the egg and transfer it to the egg of a woman with healthy mitochondria. The egg is then fertilized.

A second method involves fertilizing both women's eggs in vitro. Doctors then suck the chromosomes out of the nucleus of one egg and transfer them to the egg of the woman with healthy mitochondria. The first woman's embryo is destroyed in the process.

Botkin said it's the second approach that may raise concerns in religious circles.

Last year, the United Kingdom became the first country to permit the technique in babies. The Catholic and Anglican churches in England opposed the decision, arguing that it was unsafe and resulted in the destruction of embryos.

Botin said the scientists and ethicists on the panel took those concerns “very seriously.”

“We may not all agree on what’s the right thing or most appropriate thing to do, but there’s no question that everybody’s thinking carefully about these issues and trying to move forward in the most careful way possible to try to meet the needs of these families,” Botkin said.

Email: dchen@deseretnews.com

Twitter: DaphneChen_

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