How Safe Are Designer Babies? Mitochondrial Replacement Technique Examined

embryologist at work
In the UK, Parliament is contemplating granting regulatory approval to an in vitro fertilization technique that would swap healthy mitochondria from another woman into the egg of the mother-to-be: but is it safe? Reuters

Human rights rank as the most volatile of issues within most nations, yet when seen from the vantage point of another culture, they often cause great concern and even greater ire. A recent issue in the United Kingdom has instigated comment from representatives of other nations. The British Parliament is contemplating granting regulatory approval to an in vitro fertilization technique that would place healthy mitochondria from one woman into the egg of a mother-to-be and so eliminate the possibility of a child being born with mitochondrial disease. Yet this procedure not only modifies individual genes but the human germ-line itself — the inherited genes that are passed onto children, one generation to the next. International scientific consensus, though, views the germ-line as inviolable.

Should the U.K. cross this bioethical line and disregard scientific consensus adopted as law by more than 40 countries and incorporated in several international treaties? More importantly, is the new procedure safe for the children who will be born?

An American doctor who advises the Food and Drug Administration (FDA) recently made headlines in Britain by suggesting too many safety issues remain to allow the mitochondrial procedures. Though Dr. Evan Snyder spoke to The Independent of regulations pertaining only to the U.S., some in the U.K. have taken offense, while others believe it might be wise to heed his warning.  

Mitochondrial Disease

The estimated risk of a child being born with mitochondrial disease — a group of about 50 disorders resulting from inherited defects in the genes of the mitochondria — is only about one in 5,000. However, the disease, which may vary widely in its effects from person to person, can be devastating and cause loss of muscle coordination, visual problems, hearing problems, learning disabilities, heart disease, liver disease, kidney disease, neurological problems, and even dementia. Women often discover they have damaged mitochondria only after miscarrying repeatedly. At this point, they must decide whether or not it is best to have a baby that is genetically their own (though the law would allow them to adopt or use donor eggs).

“It is a devastating thing,” Dr. Lori P. Knowles, assistant professor, School of Public Health and fellow, Health Law Institute at University of Alberta, told Medical Daily. Still, Knowles, who has written and advised the FDA on some (though not this specific) in vitro procedures, believes it is incumbent on the people who help others to have children “to make sure that what they’re doing is truly safe. We know how to do that. We have a way to do that. And some of the problems with new reproductive techniques is that they don’t go through the regulatory instruments that are available, such as RAC.”

She is talking about the Recombinant DNA Advisory Committee (RAC) guidelines, established 40 years ago by then director of the National Institutes of Health, Dr. Robert S. Stone. The recommendations bolstered oversight of the new genetic technologies used in research. According to Knowles, RAC guidelines require longer-term experimental studies, conducted in animals, to guarantee longer-term safety. “If you’re not carefully studying these techniques in animal models, you don’t have any evidence of safety later in life, particularly in instances where you’re crossing the germ-line,” Knowles told Medical Daily. This certainly applies to the mitochondrial replacement technique currently contemplated by the British parliament. Speaking to the Independent, Snyder said, “There needs to be a little more in vitro work, there needs to be some more animal work, there needs to be longer-term follow-up on the offspring born from monkeys and probably other animals that have reproductive systems similar to humans.”

Snyder’s style of long-term thinking, though, is relatively new with regard to experimental in vitro techniques in the U.S. An older in vitro technique previously used in at least one U.S. fertility clinic already has crossed the genetic germ-line and so, too, the bioethical line.

Medical Innovation?

Back in 1997, embryologists working at the Institute for Reproductive Medicine and Science (IRMS) of Saint Barnabas Medical Center in New Jersey used a cytoplasmic transfer technique to conceive a baby. Cytoplasmic transfer involves injecting mitochondrial DNA from one woman's egg into another's. The resulting embryo is supposed to contain nuclear DNA from the mother and father, with donated mitochondrial DNA from a donor. However, in reality a small amount of unforeseen genetic overlap occurs. The children who have been produced by this method have extra bits of mitochondrial DNA, or mtDNA, from both women.

It is estimated 30 children worldwide have been born of this method, 17 in the U.S., where the FDA subsequently banned the technique. “The reason the FDA got involved was this was clearly an incident of germ-line transfer… and this was one of those instances where [the embryologists] should have gone to the RAC,” said Knowles. Instead, they characterized their new procedure as a surgical innovation, and not a medical experiment. Surgical innovations are not subject to the same oversight and regulation. At least not until the FDA gets wind of them.

Today, the very same fertility clinic has begun to investigate these 17 designer babies, according to The Independent, in order to learn more about the long-term health effects. Until now, none of these children had been checked for late-onset conditions. At a medical conference in 2002, one of the embryologists involved in their birth reported one child had been diagnosed with "pervasive developmental disorder," a term for symptoms ranging from mild delays to autism. It is believed to be unconnected to any issues with mitochondrial DNA.

Returning to the issue under review in the U.K., the mitochondrial replacement technique is not a life-saving decision made under duress in an emergency room. It’s a fertility technique intended to prevent disease, with alternatives for those affected. While Snyder believes there’s not enough data to justify going forward, others disagree. The U.K. Human Fertilization and Embryology Authority, for one, maintains scientific evidence indicates the contemplated mitochondrial replacement technique is safe.

“You have to err on the side of human lives and well-being,” Knowles said.

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