How can a baby have three parents? Lasers, software, and a joystick

After spending several years interviewing scientists and holding public forums to debate ethics and air concerns, the U.K.’s lower house of Parliament this week voted to allow babies to be born with three genetic parents.

While some call it a perversion, the procedure has nothing at all to do with kinky sex. Rather, it’s a highly advanced single-cell micro-surgery, replete with cutting-edge lasers and imaging software and, yes, even a joystick, whereby a small number of skilled geneticists is able to remove the nucleus of a donor woman’s egg (the part that plays host to some 25,000 genes) from its surrounding cytoplasm (in which reside 37 genes) and insert the intended mother’s nucleus in its place.

“It is a highly technological procedure that we couldn’t do 10 years ago,” Shoukhrat Mitalipov, the geneticist who pioneered the technique, told me from his office at Oregon Health and Sciences University just outside Portland. “This procedure uses a very high-tech imaging system – microscopes, lasers, you name it. It actually looks like a Play Station 4.”

The nuclear DNA from a patient’s egg carrying mitochondrial DNA mutations is removed and transplanted into an egg donated by a healthy donor which has also had its nuclear DNA removed. The reconstructed egg cell (oocyte) is then fertilized with the partner's sperm and an embryo is transferred to a patient. The baby will be free of risk from maternal mitochondrial mutations, but yet the biological child of the parents.

The resulting egg can then be fertilized with the intended father’s sperm using traditional in vitro fertilization, and an embryo is born.

“So then the child born will have 99.9 percent DNA from the parents, but a small portion that’s been mutated can be replaced by donor genes, and those will come from another woman,” Mitalipov said. “That’s where the term 3-parent baby comes from.”

The purpose of the procedure, also called mitochondrial gene replacement therapy, is not to tweak the physical characteristics or personality traits of a child – those reside in the nucleus, which still belongs wholly to the intended mother. Rather, it is to swap out that mother’s faulty mitochondrial DNA – those pesky 37 genes that power every cell in our bodies save red blood cells – with a healthy donor’s.

Because when mitochondrial DNA fail to provide energy to our cells, dozens and possibly hundreds of diseases can result, causing a wide range of problems that include extreme fatigue, dementia, stunted growth, deafness, blindness, multi-organ failure, and even death. (It’s a newly-discovered category of diseases, most of which have only been characterized in the past decade, and a growing number of geneticists is now exploring the role of misbehaving mitochondria in basic aging.)

The US United Mitochondrial Disease Foundation and 10 other similar groups from around the world described the condition in an open letter to Parliament as “unimaginably cruel.” “It strips our children of the skills they have learned, inflicts pain that cannot be managed, and tires their organs one by one until their little bodies cannot go on any more,” wrote the group, which includes many parents of children who have (or who have died from) mitochondrial diseases.

Dr. Gillian Lockwood, a reproductive ethicist, told the BBC that this week’s vote amounts to a “small change” in the legislation. “The biggest problem is that this has been described as 3-parent IVF,” she said. “In fact it is 2.001-parent IVF. Less than a tenth of 1% of the genome is actually going to be affected. It is not part of what makes us genetically who we are. It doesn’t affect height, eye colour, intelligence, musicality.”

For years Mitalipov has been working on this procedure so that mothers with faulty mitochondria (typically known to be faulty because they’ve had children with mitochondrial diseases) can have babies with healthy mitochondria instead, even if that part of the egg must be donated. He’s successfully performed the procedure on mice and monkeys, and five rhesus macaques are alive and healthy today because of it.

But this kind of genetic mixing crosses the so-called germ line – the series of cells through which genes pass down through future generations – which is outlawed in dozens of countries, including the UK, hence the need for Parliament to make an exception. And while it’s not yet illegal in the US, the FDA has hesitated for several years to approve the first clinical trials here. “Maybe the FDA will wait for the results if they don’t want to conduct clinical trials here,” Mitalipov said.

His critics are not so enthusiastic. “We believe the House of Commons has made a serious mistake, which we hope does not have dire consequences,” said Dr. Marcy Darnovsky, executive director of the California-based Center for Genetics and Society, in an open letter. “Under the proposed arrangement, we will not know if these techniques work or are safe. The vote would not enable a human clinical trial as is being discussed in the US, but would permit clinics to begin offering a risky and experimental fertility procedure.”

Mitalipov counters that the UK’s vote to permit select clinics to offer the procedure is in reality a clinical trial, and that performing the technique on actual volunteer women is the only way to know if the procedure is effective and safe in humans.

“It’s a revolutionary way of preventing these diseases, and we’re ready after extensive animal testing,” he said. “I understand some of the criticism, but I think it’s the patients’ families who are going to benefit, and it’s up to them to decide whether they want it or not.”

Stay tuned. The first procedure could happen later this year, thus the first baby born as a result of this technique could be arriving as early as 2016.

Source : How can a baby have three parents? Lasers, software, and a joystick, Elizabeth Armstrong Moore ( )


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