That’s because none of those talents arise from a single gene mutation, or even from an easily identifiable number of genes. Most human traits are nowhere near that simple.
“Right now, we know nothing about genetic enhancement,” said Hank Greely, director of the Center for Law and the Biosciences at Stanford. “We’re never going to be able to say, honestly, ‘This embryo looks like a 1550 on the two-part SAT.’”
Even with an apparently straightforward physical characteristic like height, genetic manipulation would be a tall order. Some scientists estimate height is influenced by as many as 93,000 genetic variations. A recent study identified 697 of them.
“You might be able to do it with something like eye color,” said Robin Lovell-Badge, a professor of genetics and embryology at the Francis Crick Institute in London.
But “if people are worried about designer babies, they’re normally thinking of doing special — different things than the normal genetic stuff.”
The gene-modification process used in the new study also turns out to be somewhat restrictive. After researchers snipped the harmful mutation from the male gene, it copied the healthy sequence from that spot on the female gene.
That was a surprise to the scientists, who had inserted a DNA template into the embryo, expecting the gene to copy that sequence into the snipped spot, as occurs with gene editing in other body cells. But the embryonic genome ignored that template, suggesting that to repair a mutation on one parent’s gene in an embryo, a healthy DNA sequence from the other parent is required.
“If you can’t introduce a template, then you can’t do anything wild,” Dr. Lovell-Badge said. “This doesn’t really help you make designer babies.”
Talents and traits aren’t the only thing that are genetically complex. So are most physical diseases and psychiatric disorders. The genetic message is not carried in a 140-character tweet — it resembles a shelf full of books with chapters, subsections and footnotes.
So embryonic editing is unlikely to prevent most medical problems.
But about 10,000 medical conditions are linked to specific mutations, including Huntington’s disease, cancers caused by BRCA genes, Tay-Sachs disease, cystic fibrosis, sickle cell anemia, and some cases of early-onset Alzheimer’s. Repairing the responsible mutations in theory could eradicate these diseases from the so-called germline, the genetic material passed from one generation to the next. No future family members would inherit them.
But testing editing approaches on each mutation will require scientists to find the right genetic signpost, often an RNA molecule, to guide the gene-snipping tool.
In the study reported this week, it took 10 tries to find the right RNA, said Juan Carlos Izpisua Belmonte, a co-author and geneticist at the Salk Institute.
Dr. Greely noted that while scientists work to get human embryonic editing ready for clinical trials (currently illegal in the United States and many countries), alternate medical treatments for these diseases might be developed. They may be simpler and cheaper.
“How good one technique is depends on how good the alternatives are, and there may be alternatives,” he said.
The authors of the new study do not dismiss ethical implications of their work. In fact, Dr. Belmonte served on a committee of the National Academies of Science, Engineering and Medicine that in February endorsed research into gene editing of human embryos, but only to prevent serious diseases and conditions, and as a last resort.
“In theory this could lead to the kind of intervention which, of course, I’m totally against,” said Dr. Belmonte. “The possibility of moving forward not to create or prevent disease but rather to perform gene enhancement in humans.”
For example, soon “we will know more and more about genes that can increase your muscle activity,” he said. The hormone EPO, which some athletes have been disciplined for taking, “is produced by a gene, so you could in theory engineer yourself to produce more EPO.”
That is the kind of genetic engineering that raises alarm.
“Allowing any form of human germline modification leaves the way open for all kinds — especially when fertility clinics start offering ‘genetic upgrades’ to those able to afford them,” Marcy Darnovsky, executive director of the Center for Genetics and Society, said in a statement. “ We could all too easily find ourselves in a world where some people’s children are considered biologically superior to the rest of us.”
Scientists and ethicists share the concerns about access. “Any intervention that goes to the clinic should be for everyone,” Dr. Belmonte said. “It shouldn’t create inequities in society.”
Unequal access is, of course, a question that arises with almost any new medical intervention, and already disparities deprive too many people of needed treatments.
But there is a flip side to ethical arguments against embryo editing.
“I personally feel we are duty bound to explore what the technology can do in a safe, reliable manner to help people,” Dr. Lovell-Badge said. “If you have a way to help families not have a diseased child, then it would be unethical not to do it.”
Genetic engineering doesn’t have to be an all or nothing proposition, some scientists and ethicists say. There is a middle ground to stake out with laws, regulation and oversight.
For example, Dr. Lovell-Badge said, Britain highly regulates pre-implantation genetic diagnosis, in which a couple’s embryos are screened for certain harmful mutations so that only healthy ones are implanted in the woman’s womb.
“They allow sensible things to be done, and they don’t allow non-sensible things,” he said. “And every single embryo is accounted for. If someone tries to do something they shouldn’t have done, they will find out, and the penalties for breaking the law are quite severe.”
According to a 2015 article in the journal Nature, a number of countries, including the United States, restrict or ban genetic modification of human embryos.
Other countries, like China, have guidelines — but not laws — banning or restricting clinical use, the article noted. Chinese researchers have conducted the only previously published gene editing experiments on human embryos, which were much less successful.
In the future, will there be nations that allow fertility clinics to promise babies with genetically engineered perfect pitch or .400 batting averages? It’s not impossible. Even now, some clinics in the United States and elsewhere offer unproven stem cell therapies, sometimes with disastrous consequences.
But R. Alta Charo, a bioethicist at University of Wisconsin-Madison, who co-led the national committee on human embryo editing, said historically ethical overreach with reproductive technology has been limited.
Procedures like I.V.F. are arduous and expensive, and many people want children to closely resemble themselves and their partners. They are likely to tinker with genes only if other alternatives are impractical or impossible.
“You hear people talking about how this will make us treat children as commodities and make people more intolerant of people with disabilities and lead to eugenics and all that,” she said.
“While I appreciate the fear, I think we need to realize that with every technology we have had these fears, and they haven’t been realized.”Continue reading the main story
For the past three days, scientists, bioethicists, and other stakeholders at an international summit in Washington, D.C. have been debating some tough questions related to the gene-editing technology known as CRISPR/Cas9.
They discussed the technique's enormous potential to cure genetic diseases and expand our understanding of human biology, as well as the safety risks and ethical hazards of modifying the human "germline" — the genetic blueprint that will be passed on to future generations.
At the conclusion of the summit, Committee Chair David Baltimore of the California Institute of Technology read a statement summarizing the committee's position on the use of gene editing in humans, which said the following:
- Basic and preclinical research should proceed. But if human embryos are edited, they should not be used to establish a pregnancy.
- Gene editing of somatic cells, whose DNA is not passed on to the next generation, falls under existing regulations for gene therapy, an experimental treatment for genetic diseases that involves transplanting normal genes into cells with defective ones.
- It would be "irresponsible" to edit the human germline, which is passed on to future generations, unless 1) the relevant safety and efficacy issues have been resolved and 2) there is "broad societal consensus" about a use of the technology.
- We need an ongoing international forum to discuss potential medical uses of gene editing, help steer policymakers, make recommendations and guidelines, and encourage coordination between countries.
Here are some of the main arguments that were made for and against human germline editing:
Why we should allow itOne of the most tantalizing reasons for using CRISPR to edit human embryos is the potential to prevent devastating genetic diseases like cystic fibrosis or Huntington's disease. These are caused by mutations in a single gene, so if you could fix that gene, the baby would be born healthy.
In April, Chinese researchers announced they had used CRISPR to modify human embryos in order to cure a fatal blood disorder known as beta thalassemia. The embryos were not viable, meaning they could not survive to birth, but it could be a preview of what's to come.
For many parents whose children suffer from genetic diseases, germline editing is a compelling prospect.
Sarah Gray of the American Association of Tissue Banks was one of those who spoke up at the meeting. Her son died of a fatal genetic disease six days after he was born, after suffering terrible seizures. As Sharon Begley reported in STAT, Gray told the attendees, "If you have the skills and the knowledge to eliminate these diseases, then frickin' do it!"
In addition to diseases with a relatively straightforward cause, gene editing could also be used, in principle, to modify genes that lower the risk of contracting or developing diseases like HIV/AIDS. However, it's not that easy — the same gene that makes people resistant to HIV also makes them more likely to die of West Nile virus, as Ed Yong reported in The Atlantic.
Finally, beyond preventing diseases, the ability to edit embryos opens up an exciting new means for understanding our basic biology. For example, it could be used to study how a fertilized egg develops into a baby, as STAT reported.
Why we shouldn't allow itHowever, like any new medical therapy, CRISPR poses safety and ethical concerns.
Although the Chinese experiment showed the technique could be used in human embryos, it also caused a number of unintended, "off-target" effects on some parts of the genome. These changes could lead to other genetic complications, some of which could be fatal.
"In my opinion, the data is not there to say [the use of CRISPR in humans] is safe or reliable," Joy Larsen Haidle, president of the National Society of Genetic Counselors, told Business Insider previously. Furthermore, "do we risk causing a different problem we didn't anticipate?"
The technology is improving, but scientists will need to do many more studies before it can be proven safe. After all, the broader field of gene therapy suffered some high-profile tragedies including the deaths of several patients.
Safety aside, many experts argue the use of CRISPR to correct congenital genetic defects is unnecessary. Doctors can already screen out many of these diseases before a pregnancy, thanks to in vitro fertilization and pre-implantation genetic screening.
New York Times columnist and science writer Carl Zimmer told Business Insider previously, "I haven't seen anybody give a legitimate medical reason [for using CRISPR in human embryos] that couldn't be achieved through other means."
If we do allow germline editing, some worry that it could lead to the creation of "designer babies" whose DNA has been carefully selected to enhance their appearance, intelligence, or other traits that are not medically necessary.
These enhancements may also be unevenly distributed among the population, leading to a society of genetic haves and have-nots.
This also opens the door to another potentially scary idea, spectre of eugenics, the racist practice of trying to "improve" the human race by controlling genetics and reproduction.
"Eugenics was not unique to the Nazis," Daniel Kevles, a historian of science at New York University, reminded the audience at the gene editing summit on Tuesday. "It could — and did — happen everywhere."
Given all of these concerns, many people at the summit or following along on social media advocated the "precautionary principle" — the idea that a new product or process which could have controversial or unknown effects should be avoided.
"When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically," according to a statement made at the Wingspread Conference in 1998.
The summit in D.C. only scratched the surface of these questions. Given the pace at which this technology has been developing, we are likely to be having many more these discussions in the years to come.