Genetic Crossroads

The intersection of biotechnology, reproduction and society

Today's Healthy Baby, Tomorrow's Designer Baby?

What are the implications of full genome sequencing of IVF embryos?

Researchers at the University of Oxford recently announced that the first baby had been born after undergoing a technique which can sequence the entire genome of an embryo. The story was accompanied by a cute picture of baby Connor Levy, fast asleep on a fluffy white blanket wearing a shirt that reads: Made with love (where the ‘o’ of love is an image of an atom.)

No one could deny the claim. His parents, a couple from Philadelphia, had tried natural pregnancy for five years, then three rounds of intra-uterine insemination, and finally IVF in the hopes of having a child. They decided to take part in Oxford’s international study of next-generation sequencing (NGS) and sent cells from thirteen of their IVF embryos. A fertility specialist looked at the chromosomes of each and found that three had the right number. One was implanted into the mother and nine months later Connor was born.

In this instance, researchers used only the number of chromosomes as selection criteria. Chromosomal abnormalities account for half of all miscarriages and lead to conditions such as Down syndrome and Turner syndrome in the babies who survive to birth. Of course, not everyone sees this type of selection as wholly benign: Some question whether decisions to terminate pregnancies when Down syndrome is identified are typically made with full information; some consider the trend a problematic form of modern eugenics, rather than a medical necessity.

But this is obviously a happy occasion for the Levy family, and for many others who are struggling with infertility. Many fertility experts believe that new forms of genetic testing can greatly increase success rates and efficiency of IVF overall, particularly for older parents. Michael Glassner, the couple’s fertility specialist, firmly believes in the potential of NGS and stated, “In five years, this will be state of the art and everyone who comes for IVF will have it."

Genetic testing of embryos for the purpose of screening out disease does already occur. According to the Human Fertilisation and Embryology Authority, there are 263 medical conditions (and another 32 under consideration) that are considered serious enough to warrant the use of preimplantation genetic diagnosis (PGD), the genetic screening of embryos prior to implantation.

But NGS carries potentially broader implications.

This “revolutionary” process is capable of sequencing an embryo’s entire genome, providing an unprecedented degree of information about it prior to implantation. This would give parents much more (but often imperfectly understood) information, including about the child’s chance of developing certain diseases, as well as non-medical characteristics such as eye and hair color.

Is this what parents want? William Saletan at Slate is concerned that we’re only reporting the successes of embryo testing and warns that

"We’re discarding embryos over the possibility of breast cancer, which rarely strikes before age 30, and early-onset Alzheimer’s, which doesn’t begin till 40 or 50. We’re rejecting them to avoid the risk of conditions such as rhesus blood disease, where onset is dubious (specific antibodies have to cross the placenta to the fetus) and the cure rate is 70 to 95 percent. We’re even chucking embryos just because their genes make them useless as tissue donors."

To move from testing embryos for specific genetic mutations based on family history to testing entire genomes no matter what would be a huge shift. Saletan seems largely concerned with the fate of the embryos themselves, but there are other reasons NGS would put parents-to-be in an uncomfortable position. How would people longing for a child weigh one abnormality or imperfection against another, or contemplate abstractions such as a 50-60% disease risk against a potential human life?

Nevertheless, there are already those with far broader hopes for the technology.

Zhao Bowen, the 21-year-old who oversees BGI Shenzhen’s multimillion-dollar research project searching for the genetic underpinnings of intelligence, explicitly hopes his research will be used to breed smarter babies. According to Wired, those on his team “expect that within a decade their research will be used to screen embryos during in vitro fertilization, boosting the IQ of unborn children by up to 20 points.”

Momentarily putting aside the fact that there is currently no evidence to suggest that genetic selection for intelligence is possible, if such research does pan out, it will largely be limited to the privileged elite. As Heather Long argues in the Guardian, “If we think the gap between the haves and have-nots is large now, just wait until this technology is used to pre-select characteristics for success.”

Of course, the process of selecting among existing embryos is somewhat limited in its design capabilities. It is important to note the difference between choosing traits based on selection, and actually modifying the germline of embryos in order to create a desired result.

An editorial in New Scientist noted that the announcement of Connor’s birth “brings the prospect of designer babies one small step closer,” but that “until it becomes possible to genetically engineer embryos rather than just select them, true designer babies remain in the realm of science fiction.”

The authors agree that we shouldn’t simply sit back and wait for that to happen. But they fail to mention how close this possibility truly is. The UK Government is preparing right now to draft regulations that would undermine the country’s ban (as well as international law and consensus) to allow embryo manipulations that would effect all subsequent generations. The justification is that this step would be a limited one aimed at allowing a small subset of the women with very serious mitochondrial diseases to have a healthy and mostly genetically related child. But it would provide the biggest push to date down this particular slippery slope.

Jessica Cussins is a researcher at the Center for Genetics and Society.

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