Latest way to beat infertility: ‘three-parent babies’
For $ US50,000 and up, Dr. John Zhang is offering women in their 40s a “solution” for age-related infertili ty — swapping chromo- somes between two women’s eggs, resulting in a child with, technically speaking, three genetic parents. Some of the hopeful mothers-to-be he’s screening are in Canada.
Zhang, who spearheaded the delivery of the world’s first baby born l ast year f r om hi s c ontroversial DNA- blending technique, is now preparing to offer the procedure to older women desperate for their own biologically related babies. “We hope to begin cases within the next few weeks,” he said in an email to the Post. Canadian women are among those being considered for the revolutionary — and some say hugely ethically objectionable — procedure.
The criteria are straightforward enough: the women have to be aged 42 to 47, they must have failed at least two rounds of traditional in vitro fertilization and still have their periods. They also have to be prepared to pay US$50,00 to $100,000.
Zhang’s “three parent baby” procedure was originally presented as a noble goal to prevent women from transmitting devastating mitochondrial diseases to their children.
However, the Manhattanbased, Chinese- born scientist is now also targeting the lucrative fertility industry, promising to “reverse the effects of age” on human eggs.
His procedure, known as spindle nuclear transfer, involves removing the nucleus, which contains the majority of maternal DNA, from one woman’s eggs and injecting it into the egg of a younger donor.
The donor egg, stripped of its own nucleus, has what the older egg doesn’t: A more youthful mitochondria. Mitochondria work like miniature power plants, supplying energy to virtually every cell in the body. Evidence suggests that as women age, the energy- output of the mitochondria decreases, meaning less power to fuel cell division after fertilization, making it harder to achieve a successful pregnancy.
The new, “reconstituted” egg, which conceivably could be decades younger in age than the woman herself, is fertilized with the male partner’s sperm, the resulting embryo transferred to the woman’s womb and, if all goes according to plan, a healthy baby is born.
According to Zhang’s new startup, “Darwin Life,” as reported by Technology Review last week, successfully swapping its nuclear contents turns the donor egg into a 98.9- per- cent genetic match to the mother (the remaining 1.1 per cent of genetic material coming from the other woman).
Last S e pt e mber, t he world’s first baby conceived via spindle nuclear transfer was born to a couple from Jordan. The mother was a carrier of a lethal, progressive neurological disorder caused by a mutation in her mitochondrial DNA that led to the loss of two other children. Zhang performed the egg collection and mitochondrial replacement in the U. S. but the actual embryo transfer itself was performed in Mexico, circumventing American laws effectively banning the procedure in the U.S.
Details of the work — backed by privately funded research — were only revealed this past April.
In an earlier interview with the Daily Mail Online, Zhang said the possible applications could be “unlimited.” Some have raised the spectre of genetic enhancement and “designer babies,” using the technology to essentially edit eggs and sperm of undesired traits.
“This technique is a new platform,” Zhang told the Daily Mail. “How far it can go, I really cannot imagine.”
Dalhousie University bioethicist Francoise Baylis accused Zhang of rushing to commercialize an expensive intervention for which little published evidence exists to support its safety or efficacy.
“This is unethical, i rresponsible and exploitive,” Baylis said in an email, adding there could be unknown harms to the mother, the egg donor and potential offspring.
“The chance of failure with IVF for women over the age of 45 is 98 per cent,” she said. “At best (and this is unlikely) this experimental intervention might reduce the chance of failure to 70 per cent.”
“This is about selling false hope.”
Zhang’s response to his critics is that most scientific advancements were initially met with skepticism and moral outrage. “When the world’s first heart transplant occurred in South Africa, the community was afraid the doctor had transferred the soul of one person into another,” he said. The first babies born from IVF in 1978 were considered “an unnatural abomination.”
“We have the world’s first successful ( three- parent) birth,” he told the Post. “Of course there is need for longterm study of that baby, and other cases. ( However) we had 20 years of research before moving to the first case study.”
University of Saskatchewan-based infertility expert Dr. Roger Pierson said that as science moves closer to learning how to turn somatic cells, body cells, on and off, “we know that we’re very close to being able to make a gamete out of any type of body cell.
“Right now we make gametes naturally — men make sperm, women make eggs. We put them together, magic happens, and you have a baby.” Pierson said.
“Here we’re starting to understand reproduction at a cellular level,” he said. “The next step is to say, well, if I can do this in an egg cell, why can’t I make an egg cell? Why can’t I make a sperm cell? Why do you have to be female to make an egg?
“There are big- picture questions, and what Zhang’s done is give us another step on the ladder to attacking those big-picture questions,” Pierson said.
While the experiments are being done one person at a time, the effects could be passed through generations, he added.
“We fixed this person’s infertility — we change their microcellular structure, and that child goes off and reproduces. What is it they pass on? And what is it their children pass on?
“It’s accelerating our evolutionary process in a completely unprecedented way.”