Kate Johnson

October 20, 2016

SALT LAKE CITY — Details about the baby born with the help of spindle nuclear transfer, known as the "three-parent baby," were revealed during a late-breaking session here at the American Society for Reproductive Medicine 2016 Scientific Congress.

Reactions ranged from dismay to admiration.

Condemnation for "changing the heredity of humans forever" came from Ke-Hui Cui, MD, PhD, from The Georgia Center for Reproductive Medicine in Savannah. And praise and support for the team's "good work," came from Kutluk Oktay, MD, PhD, from New York Medical College in Valhalla.

The baby, conceived with a "reconstituted" oocyte, is now 6 months old, and "no complications or abnormalities" are evident, said team leader John Zhang, MD, PhD, from the New Hope Fertility Clinic in New York City.

The procedure was performed at New Hope's site in Guadalajara, Mexico, to bypass the American ban on mitochondrial manipulation.

"Everything in Mexico was done within the regulatory frame that allows for these fertility treatments," said Alejandro Chavez-Badiola, MD, medical director at the Mexican clinic.

"We are in touch with the authorities and have discussed how we want to move forward," he reported. "Now that we have this first live birth, we are expecting families to come to us and we are hoping to be able to help them."

These parents opted for spindle nuclear transfer after the death of two children who had inherited their mother's mitochondrial mutation, known as Leigh syndrome.

And there will be more. "We've been approached by patients from different parts of the world. We have not taken any more cases, but we have had requests," Dr Zhang said.

Dodging Mutated DNA

Part of the reason for this is to make sure the baby is healthy, he explained. Long-term follow-up will be critical, but so far, sampling of the blastocyst, as well as tissue taken at the time of delivery, shows that he received less than 10% of his mother's mutated DNA.

This "load" is presumed to be too small to cause any symptoms, Hui Liu, MD, PhD, an embryologist at the New Hope clinic in New York City, said in a separate presentation.

Only five maternal oocytes were morphologically normal and suitable for the procedure, Dr Liu explained. But before the spindle nuclear transfer was performed, next-generation sequencing showed that all five had a mutational load close to 100%.

This gene will be stopped.

The procedure involved removing the nuclear spindle — the mother's DNA powerhouse — from each oocyte, and transferring it to a donated oocyte with its spindle removed. The resulting four reconstituted oocytes, containing most of the maternal DNA but very little of her diseased mitochondria, were then fertilized with the father's sperm. Only one normal embryo was obtained.

To prevent transmission of the syndrome, the team plans to transfer only male embryos for the time being because mitochondria are maternally inherited, Dr Zhang said.

"Theoretically, the family tree from this boy will no longer have the genetic defect," he told Medscape Medical News. "This gene will be stopped."

"I am relieved that the baby appears to be fine, but would like to know about later health," said Joanna Poulton, DM, professor and consultant in mitochondrial genetics at the University of Oxford in the United Kingdom.

Mitochondrial treatments such as this were recently approved in the United Kingdom. Clinics will be able to apply to the Human Fertilisation and Embryology Authority for permission to use them, she reported.

Mitochondrial Treatments Allowed in the United Kingdom

Dr Poulton said she is uncomfortable that this particular case involved side-stepping American regulations. "I am happy that this procedure will go ahead under close scrutiny in the United Kingdom," she told Medscape Medical News. "I am not in favor of medical tourism for a procedure like this, where good genetic counseling for the family and follow-up for the child is important."

But Dr Oktay said the physical location of the clinic is not really important.

"As long as it's done with proper oversight and in a responsible way, with carefully selected patients, I think the general opinion is it has a novel purpose," he said.

This is one of the "great examples of preventive medicine," he suggested. "You're not just treating one patient, you're treating generations down the road. Your intervention corrects problems for generations."

"Everything we do is because there's a patient in need across the table from us," said Jamie Grifo, MD, PhD, from the NYU Langone Fertility Center in New York City, who pioneered some the early work in this field.

"We're not out there just trying to climb the next mountain because there's a mountain out there. There's a clinical problem and we're trying to find the best solution we can," he told Medscape Medical News.

Dr Zhang, Dr Liu, and Dr Chavez-Badiola are from New Hope Fertility Clinic responsible for the procedure. Dr Grifo pioneered some early work in this field. Dr Cui, Dr Oktay, and Dr Poulton have disclosed no relevant financial relationships.

American Society for Reproductive Medicine (ASRM) 2016 Scientific Congress: Abstract O-53, presented October 17, 2016; abstract O-267, presented October 19, 2016.


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